I was driving around with my girlfriend when I spotted a 19 inch (i'd say) westinghouse B&W tube tv. With my favorite word on it "Free".
So I took it in a heartbeat and took it home. Upon inspection everything seemed Ok (nothing was leaking blown up or covered in strange resin). Today I tested all the tubes except the half wave rectifier tube. They were all in the green except 2. One sorta jumped around the other was just a little weak(These were small tubes) I also didnt check the two tunning tubes as they were in the back and I was unsure of when it was last plugged in. (The tv has a total of 20 tubes including the picture tube.)

After this I had to at least try it out

I decided to plug it in. And i'm pretty sure all the tubes were glowing including the projection tube(Scary damn thing xxxradiationxxx) But after about 20 seconds nothing. No sound, no picture I flipped through the channels and nothing. I was dissapointed, but I knew it wouldn't work when I found it.

So any one have any suggestions for me. Little things to check. In an attempt to track down the problem. I don't wanna spend any money on this tv. Its big sorta ugly and a B&W radiation machine. But if i could see it turn on once that would be cool.

Or should I just screw it, and rip it all apart take all the chokes and audio transformers. And anything else you think would be useful?

It has a 21alp4a Picture tube. If that helps anyone on getting an idea of the size and type of tv. It also has 13 channels if that helps put a date on it.

Thanx. and if anyone wants to see a picture just ask I'll do it No worries. Ask any questions you want.

Oh and I own a didgital voltmeter :) handles 1000volts and doesnt measure capacitances.
So thats my other testing supplies other than my tube tester. Which is a Dyna jet model 606 Any1 know if its any good? I also got it free :)

you will have to replace the wax capacitors and then check for open/drifted resistors before all

If you dismantle the set, i'd also keep the tubes and the speaker

Anyway, a B&W TV emits little if any harmful radiation.

You think maybe if I hit it a couple times....haha its a long shot but i did notice solder balls and bits inside the frame . Ha I just can't bring myself to strip it just yet

Don't do it!

Sounds like the B+ isn't running. Check for a fuse or circuit breaker. I'm gonna guess it's a series-string set. (would use odd number tubes, starting with numbers like 7, 8, 11, 13, not all 6's and 12's)

Don't strip it!!

It minimum it will need new capacitors to function properly. THe westinghouse sets usually had a large sand-type dropping resistor in the B+ supply that would go up in value or open, preventing operation of the set other than the tubes lighting.

You will want to replace the electrolytic capacitors in the power supply, as well as all paper capacitors. See http://antiqueradio.org/recap.htm for basic advice on that.

If you can find a label anywhere with the model number (http://antiqueradio.org/identify.htm), perhaps someone can send you a scan of the schematic for this set. I wouldn't try to restore any old tube TV without a schematic, since it involves replacing dozens of components, with many opportunities for making wiring mistakes.

There is no danger from radiation. But be careful not to stick your fingers into the chassis if you have it powered up on the workbench (which might kill you or kick your butt across the workshop).

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Don't strip it !
Rather than strip it , give it to someone who would enjoy doing a restoration .
If you want to get it going , expect to do a recap as everyone else has also said .
Most likely the it would operate with the original electrolytics cans , however the wax/paper caps will all have leakage .
And also I have found that the early plastic covered caps , like "SANGAMO" brand are also leaking .
The parts most likely wouldn't cost you more than $30.00 .
I would keep it , and do a recap on it.
As for radiation , the amount produced by a B&W television is very low .
I have had my head stuck in TV's off and on for the last 20 years , and Im still here . :yes:

how dead could the picture tube possibly be though. If this is dead I may have no hope of fixing it. Or would it still work and have a weak picture?
I think it might be dead because all the tubes are in good condition except two, which I think would still at least get it to show picture.

I have no money right now to replace the capacitors but it does sound like a fun job. I guess I will try and check the B + supply tomorrow and its resistor for starters. Would taking the chassis out help me, I don't really wanna do to much unnecessary stuff. That might break it :S

Oh...and if I touched what I thought was the positive side of a large diode (Its blue with heat vents I know its a diode)with my voltmeter and the other end to the chassis should it of given me a large DC voltage? Possibly for the Picture tube or other tubes B+ supply?

Or would this B+ voltage more likely be rectified in an actual tube, Half wave or Other?

And am I looking for the B+ to the picture tube or all the other tubes. I don't know much about tv's but have sorta made some tube amps. And learning is fun.:thmbsp:

With the symptoms you are describing, this TV most likely had a power supply
failure a long time ago and was set aside. Ther is no reason to conclude without
some testing that the picture tube is dead.

The thing you are describing as a large blue diode with vents is most likely a selenium
rectifier for the power supply. Do a little research and you will find out that those
are prone to failure and are usually replaced by more modern silicon units.

Be very careful, but working on this TV should be a rewarding experience.

As someone else suggested, if you could post some extra info, it would help us
to help you. Things such as model number, list of tubes, etc.

The 21ALP4 picture tube type indicates that this is nominally a 21-inch TV.

Good luck, please do keep us posted.

Does the cabinet look like this one? http://www.geocities.com/wa2ise/radios/west-tv.jpg

Alright i'll have a picture of this tv Both outside and inside in half an hour along with a list of tubes and there purpose in this Tv

THe cabinet you showed me is pretty close but it doesn't have that nice colour. Theres a lot more brown detail. But yes the cloth on the bottom and controls at the top.

Pictures soon!

Just can't wait!

K for some reason it doesn't wanna let me upload my pictures so I guess I'll just type what I got. The model Number is either 5-3533 or it's 65j 941-1.

4bq7a Rf amplifier
5at8 Mixer
3cb6 1st pix I.F. and another for 2nd pix I.F.
5am8 3rd pix I.F. + 2 DET
12by7a video amplifier
21alp4a pix tube
3au6 sound I.F.
3al5 FM detector
3av6 Audio detector
12c5 audio output
3au6 keyed AGC
7au7 sync amp/noise killer
5u8 sync.sep/vert discharge
12b4a Vertical output
3al5 horizantal phase detector
7au7 horiz oscillator
12bq6gtb horiz ouput
1x2b h.V. rectifier
12ax4gta damper

and i'll try to get those pictures posted as soon as it starts working.

It's a Christmas Miracle!

PICTURES!

Do I see the French word AVIS (meaning warning) on the metal cover in the upper
right corner? This could be a Canadian made set, or one marketed under the
same model number in Canada.

As was expected, this is a series string set, meaning that the designers did away
with a power transformer, and that most tube heaters are wired in series. If
any of those heaters fails, the tubes won't light up, but you already checked that.

If you undertake removing the chassis (a step that is almost mandatory to do
some serious repairs such as replacing the filter capacitors), be very careful with
the following: the picture tube base may have unglued from the glass, and pulling
the socket to remove it could just tear the base away, break the fine wires and
possibly destroy the tube. Always make sure that connections between the
various parts of the system are properly undone before you pull out anything.

Series string sets are somewhat trickier to service than those with a transformer,
but they are capable of good performance.

Good luck.

P.S.: If this is indeed a Canadian market set, give me until next Monday
to find a schematic for you. I might have it.

Actually your right. The Tv was made in Montreal apparently. I thought that was pretty cool.
If you could find a schem that would be great...Thanks
Rudy

I've taken the set out of the box to get a better look at it. And have some more pictures of some parts. Like one part that I think is the "sand resistor" (only measured 25 ohms) and it was physically chipped. Also I found one of the only looking possibly burnt capacitors. It is conneceted to the 1x2b and just looked charred black near the bottom. Check it out. Is this a good spot to start.?

I've also been checking random resisitors and all of ones near the burnt cap. They all seem OK....not perfect but close enough to what they should be. Are the resistors normally Ok in older TV's?

Now to test for the B+ supply for the tubes what should I do. Plug it in with a voltmeter hooked up to the larger capacitors. Or how? should I go about this. With my little tube amps this was fine But they don't make voltages in the quadrupal digits.

The B+ in those sets runs somewhere between 375 and 500v. YOu need some service literature like a sams photofact to tell you what the voltage measurements should be.

Just measure between the terminals of the filter caps and ground. Look for excessive AC voltages at the caps too. That usually indicates a leaky or open capacitor.

On a "dead" set--i.e. no picture and no hum in the speaker, but tubes all lit, it is usually failed B+ off those two blue selenium diodes. With the set unplugged arrange an alligator clip hook up at one of the twist-lok tabs where the common negative should be. It might be directly connected to the chassis pan, but sometimes a maker will get weird and isolate the pan. Clip the other end of the alligator jumper to the negative test lead of your meter, and set it so that it can read up to 500-600volts. Plug in the set and fire it up, and you can quickly ascertain whether or not there is B+ present at the voltage doubler circuit comprised of the two blue rectifiers. It'll be around 300 volts usually.

If there is voltage present then listen to the "doghouse" of the set and--if you have young and healthy ears--determine if you can hear a dog-whistle high pitched sound indicating horizontal sweep. If there is then you may see some boosted B+ sweep-signal-derived off the damper tube and a winding of the flyback coil--about 400 to 500 volts. If you are not hearing the 15.75KHz whistle then have a quick look at the anode of the horizontal output tube to see if its plates might be turning red from lack of drive-induced negative grid bias. Pull the plug if it is, or lose the tube, or perhaps blow a fuse. In fact staring at the plate of the 12BQ6 should be the first thing you do after powering up; if there is no drive the tube can go up quickly.

If there is no boosted B+ then in some sets there is no audio either, as the sound output tube draws from boosted B+ and "moonlights" as a voltage regulator, feeding about 130 volts off its cathode to such as the IF stages and the tuner. Thus there will be little or no action from the set at all.

You may already know these things, but.... Left hand in pocket is a good rule. Places not to go with your voltmeter test prod are anywhere within the "doghouse" (high voltage cage), the heavy lead running to the anode well on the back of the picture tube, the anode cap of the horizontal output tube and the anode pin of the vertical output tube.

Also--like the rule about loaded/unloaded guns--there is no such thing as a fully-discharged kinescope (picture tube)!!!! They make a very efficient capacitor, and can hold a charge for decades. AMHIK.

There is no hum Or red glowing tubes that are being overloaded i'm almost sure. The set literally gives no action other than tubes all glowing red. I will go test the selenium rectifier momentarily to see if it is truly failed.

And THANK YOU for the warning about the DOGHOUSE. I was poking around in there two days ago :S. Not for voltages but just to test the tube. Thank God I was being careful.

......and all you guys Thanks
I was gonna just strip this thing when I found it, and probobly would have. But now that I know theres hope I have this dieing urge to play my nintendo and atari on it :P

There DEAD, there really dead.

From the chassis(witch the selenium rectifier's ground was directly soldered to) The possitive side of the selenium rect shows a peak voltage of 30 dc. The other one shows a whopping 5.

So is this where the B+ originates from? DO the other B+ just get stepped up from the volatges made in the selen. rect?

So I'm guessing I need that for sure. But what will I be replacing it with? Another selnium one that's the same. Or is there a better new diode used when replacing these old ones cause I don't know first hand. This is also my first TV repair job, and I'm lovin it.

Rudy

Alright I have 2 or possibly more 6a2 diodes. I think they are rated at 6amps 200 volts. And I know I built a 250 volt power supply from them. Would this be sufficient as a replacement. Cause from what I read the selenium are much larger than the silicon ones. So maybe these two guys would work? They are about 1 cm long and .7 cm in diameter.
Like I said I have no money so I wanna do anything I can with what I've got. (.91 cm x .91 cm actually)


And If I do have more than one can I double them up or put them in series to increase the voltage they can handle? I know it can be done with a cap

And one more question. The caps in this TV do you think there full of PBCs. Or is there no doubt they are

Those selenium rectifiers are probably rated maybe 1/2 amp. Voltage I'm not so sure about though. Probably you'd want something to handle a little more than 200. I used 1N4007's to replace the selenum stacks in my Philco.

PCBs are usually found in oils. THose caps are mostly paper and foil. The electrolytics have some sort of borate in them usually, no PCBs. THe rest are dry (well, other than the water they've sucked up over the last half century)

Handy tip for testing the HV lead. Use one of those compact flourescent lamps or even a small flourescent tube held near the HV wire. If it glows, you have high voltage. Don't get your fingers too close to this, the HV lead probably runs 15,000 volts or so.

That's a handy trick I must say.
I guess i'll go grab a diode tomorrow. I'm sure I can scrounge 50 cents.
Then do you guys think I should give it a whirl..or no?

Alright I have 2 or possibly more 6a2 diodes. I think they are rated at 6amps 200 volts. And I know I built a 250 volt power supply from them. Would this be sufficient as a replacement. Cause from what I read the selenium are much larger than the silicon ones. So maybe these two guys would work? They are about 1 cm long and .7 cm in diameter.
Like I said I have no money so I wanna do anything I can with what I've got. (.91 cm x .91 cm actually)


And If I do have more than one can I double them up or put them in series to increase the voltage they can handle? I know it can be done with a cap

And one more question. The caps in this TV do you think there full of PBCs. Or is there no doubt they are

A good diode to use is the common 2.5A 1000PIV silicon type. Also any associated electrolytic capacitors in the voltage doubler circuit are likely dried open, hence your low voltage readings. Be sure the working voltage ratings of the replacement capacitors are the same or higher than the originals. Series hookups of capacitors can be done to increase working voltage ratings, but shunt resistors of about 220K ohms and 2watt or better should be used, as no 2 electrolytics have the same leakage, and one will almost always hog all the voltage from the other. Generally it is a better practice to avoid series connection, but paralleling them is OK to increase total capacitance, provided all the caps are of the appropriate voltage rating.


Make sure you get the polarity correct on all those diodes and capacitors....unless you like extreme excitement....

A source of diodes and caps would be old PC power supplies. They usually have doubling power supply circuits on the line side.

Thank you wa2ise,
You made me remember I had an old fried superbrain charger. Full of diodes. Turns out they are 6a10 much like the other ones I had but rated for 1000 Volts! 6 amps
I'm gonna go put them in now

so the diodes are in. I also left the old ones in but disconneceted them from the circuit. Looks cool.
And if I am correct I wanted the stripe of the diode (cathode) To be connecetd to the + side of the capacitor?

Well I'm gonna test it. After I build a bombshelter around it. If you don't hear from me again.....Tubes Rule! :P

Alright so I put the diodes in, No issues. And booted it up. And once again was left with about 30 volts Then when the heaters finished heating it dropped.
I traced where the ac mains lines actually go and one goes to the damper tube base. But is not actually connected to the tube. Its connected to a sand resistor. Some one else mentioned it could have been this resistor.
I measured in this resistor at 25 ohms. Is this an average value for this type of resistor or is it wayy off?

The other mains goes to ground then the one of the new diodes I put in.
Also one side of the mains is hooked up to a small cap then travels to another larger cap. To ground again..I think

Make sure they are in correctly ....

Alright so I put the diodes in, No issues. And booted it up. And once again was left with about 30 volts Then when the heaters finished heating it dropped.
I traced where the ac mains lines actually go and one goes to the damper tube base. But is not actually connected to the tube. Its connected to a sand resistor. Some one else mentioned it could have been this resistor.
I measured in this resistor at 25 ohms. Is this an average value for this type of resistor or is it wayy off?

The other mains goes to ground then the one of the new diodes I put in.
Also one side of the mains is hooked up to a small cap then travels to another larger cap. To ground again..I think
25 ohms sound alright to me , I have a bit different westinghouse schematic , and there is a 7.5 ohm , them the cap , then the diode .
Does the resistor look burned , or have cracks in it ?

I'm almost positive I have them in right. I get just about the same voltage as before with the originals in. Just a little better. SO i think I got that part right.

But the electrolytics are dead is the real problem. It charges up to 30 then drops to 3 volts when I turn it off. It should be staying closer to 30 for longer should it not?

Anyone think replacing them would solve the problem?

25 ohms sound alright to me , I have a bit different westinghouse schematic , and there is a 7.5 ohm , them the cap , then the diode .
Does the resistor look burned , or have cracks in it ?
Yes I beleive i have a picture of it posted. It has a chip on one side. I'm not sure if its the kinda chip that affects performance But i'm hoping it might be.
I wouldn't say it looks burnt or anything else though.

If you havent' already replaced the electrolytics, that is surely adding to your problem, along with bad paper capacitors.
I just don't understand how it is people take un restored stuff and put so much faith in it working.
Bill Cahill

Its connected to a sand resistor. Some one else mentioned it could have been this resistor.
I measured in this resistor at 25 ohms. Is this an average value for this type of resistor or is it way off?

The other mains goes to ground then the one of the new diodes I put in.
Also one side of the mains is hooked up to a small cap then travels to another larger cap. To ground again..I think

Those sand resistors are combination resistor and fuse. "Fuseistor". Most of these I've seen are on the order of 7 ohms. You should see a number printed on it, that number is usually the resistance.

The rectifier circuit sounds like a doubler. One of the mains (powerline) going to ground, the other mains line going to an electroytic capacitor. The other side of that cap has a diode, the other end (its anode) of which going to ground. And a 2nd diode, where the 1st diode connects to the cap, the other end (its cathode) of the 2nd diode feeds a second electroytic cap, the other end of ths cap goes to ground.

Selenium rectifiers usually had "+" marked on their cathodes, as if to say, "apply AC to the other end, and here you will get positive voltage".

Yes it is a voltage doubler working as you described.
And as for the sand resistor it has the number 2 on it. And I thought it may be an ampere rating cause like you said "Fuseistor". And if it is supposed to actually be 2 ohms it is 23 ohms off.

Is there a possibilty that this sand resistor is actually for the heaters. I sorta traced where it goes. It went to hz deflector tube (12bq6gtb) and definatley connected to pins 7 and six (7 is heater connection 6 is blank)

Does anyone think that a recapp is all she needs and would bring this tv back from the dead? Or would it still most likely need further work?

As someone who has repaired many a b&w tv the first thing I suspect is the high voltage(about 20kv @1ma).If you touch it you will live(unless you have a pacemaker:D)Its like getting shocked with a sparkplug wire.I know a way to check th high voltage with a screwdriver but I'm wary of telling you how in case something happens to you. These tv get dust inside and it doesn't take much to overload the H.V. You could try cleaning around the H.V.(its the part of the tv with all the dust around it.The high voltage attracts dust like an electrostatic air cleaner.If the horizontal flyback transformer is gone(part of h.v.)then its a lost cause.Be careful as some chassis were conected directly to one side of the a/c line so depending on which way the plug is in the wall the chassis may be live or not.The value of doing this is not n the tv but in the learning experience of trouble shooting.Good luck and be careful:yes:

Does anyone think that a recapp is all she needs and would bring this tv back from the dead? Or would it still most likely need further work?


If you replace those two electrolytics in the voltage doubler circuit you may well get the power supply operating. Either one or both could be dried out to the point that they are no longer capable of doing their job.

You will get the practice in capacitor replacement, as you have many more to go after those 2. But at least getting those done should get you back to a higher voltage level. If a fuseable resistor or sandbrick resistor opens it's almost always all or nothing--to wit you wouldn't likely be seeing the paltry 30 volts you are seeing.

If you have to burn any gasoline running to the radio shop for capacitors you might as well shotgun the entire power supply and replace all the electrolytics; the odds are that they are all not long for this world if not already expired.

"Be careful as some chassis were conected directly to one side of the a/c line so depending on which way the plug is in the wall the chassis may be live or not."

HAHa I learnt this the hard way already. Testing to see if caps are hot Zaap. I was so happy, I thought I got the HV working again. But after some thought I realized it was 60hz because thats just how it felt. Bugger I said( I also didn't think it could get me with just one hand in there...maybe 2 fingers touched)

And just some test results from the caps. I got the charge to go up to 40v. They seem to be fixing themselves a little every time I power it on(30 to 40) But I don't think they will fully recover. Also I measured 60 volts ac With my tester at the same points. And it jumped around a little (40-90 vac).

With this in mind could it be the caps. I wanna say yes. But if anyone thinks its a little far fetched for the caps to bring the voltage from 30 to the proper 250 or w/e it should be. please say so.

Rudy

"Be careful as some chassis were conected directly to one side of the a/c line so depending on which way the plug is in the wall the chassis may be live or not."

HAHa I learnt this the hard way already. Testing to see if caps are hot Zaap. I was so happy, I thought I got the HV working again. But after some thought I realized it was 60hz because thats just how it felt. Bugger I said( I also didn't think it could with just one hand in there...maybe 2 fingers touched)

So replacing the larger caps could give me a boost from 30v up to my proper voltage?
And just some test results from the caps. I got the charge to go up to 40v. They seem to be fixing themselves a little every time I power it on(30 to 40) But I don't think they will fully recover. Also I measured 60 volts ac With my tester at the same points. And it jumped around a little (40-90 vac).
With this in mind could it be the caps. I wanna say yes. But if anyone thinks its a little far fetched for the caps to bring the voltage from 30 to the proper 250 or w/e it should be. please say so.

Rudy

There goes one of your 9 lives as a repair technician:D

Alright so just wondering if these will be hard to find. Cause I've been looking online and I'm not seeing the exact values. 33 and 220 mfd and stuff
and maybe a guesstimated cost by someone?
30 mfd 300 vdc and it says 375 something ac
20 mfd 300 vdc 375 something
100 mfd 150 vdc 250 ac something

200 mfd 150 vdc

160 uf 300v

and 160uf 150 v

And I turned it on again. Got 45 volts. I should just turn it on 50 more times :P

The second voltages given on those are surge voltages. Not ac voltages.
With today's higher line voltage, I reccommend highly using 450 volt filters.
Bill Cahill

The values of caps is not that critical.Usually the manufacturer made the capacitance as small as possible because back then they costed more than today. The next higher value in cap and the same or higher voltage should be ok. eg. 34ufd 280v ,a 39ufd 350v would be fine. just go higher in cap and working voltage. These days caps come in standard values(same values)as resistors.(39,47,56,68 ect)Just use higher value of cap and voltage and you should be fine and be careful!:yes:

Alright so where does everyone get there caps from?
I went to some places in Winnipeg and it was like 8$ for each 350 volt cap. And at the other store it was nearly 17$. SO maybe the internet is the way to go or something, any one have any suggestions?

Oh and can I use axial caps. The kind with leads on both sides. Or must they be surface mount can type. With both leads on the bottom?
I didn't think it mattered but maybe it does.


OOOO I just found a bag of my capacitors and I had waaay more than I thought
I found a 33 uf 450 dc
a 40 uf 450 dc
20 uf 450 dc
100 uf 250 dc
30 uf 450 dc
i have enough 33 to parralel them up with 100 and make a 160
But these are all axial type with leads on both sides so are they useless? DO they they have to be "radial" (both leads on the bottom)

For just getting the TV to work, you can experiment with any properly rated
capacitors that will fit. Some restorers dismantle the innards of the big old
tubular capacitors and install modern replacements inside. I just saw a thread
for an old Zenith color TV with fine pictures illustrating the latter procedure.
See post 19 in this thread:

http://www.audiokarma.org/forums/showthread.php?t=170055&page=2


Be careful with capacitor that have been lying around for some time. Even
though they were never installed, they may have dried out. But then again,
they might work fine. Just be sure not to install them backwards.

Sounds like its worth a try to me. And wow these are tons smaller than the old ones.
I'm gonna switch the ones that I can, as for the one I can't replace should I fear it exploding or anything. Or should I just give it a shot, then replace it later if all goes well.

Oh and can I use axial caps. The kind with leads on both sides. Or must they be surface mount can type. With both leads on the bottom?
I didn't think it mattered but maybe it does.




Electronically, except for the IF strip and the tuner, it doesn't matter. And you shouldn't need to change anything in the IF or tuner anyway, those caps there are usually ceramic discs and rarely go bad.

Even the manufacturers will use axial caps in a pinch where a radial cap was designed for, on a circuit board. They would use caps with leads long enough so they can bend one end over to reach the circuit board with the cap standing upright. They want to ship product, and can't wait around for the radials to show up in a few days.

"Woot I know what I'm doing today then. Maybe I'll have a picture of a working Tv for you Guys today. Or a Tv with alot of blown up capacitors but I don't even care at this pointcause I just remembered I was gonna strip this thing originally.Ha"
I said earlier


Well I went, and was gonna try, till I took a better look. I can hardly get in back there to switch them. They are soldered in pretty well. And since they have 3 caps in one can I can't figure out which mfd goes to which lead. And without a schem I have nothing to go on. And to take the CRT out of this thing Is a big job in itself. The whole actual Tv and all its compenents are attached to a board. which came out of the tv box as a whole. So I at least wanna do all the caps when I do this Job. Not just the ones I can at this moment.
Bugger

It can be tricky to figure out those multicaps but you can do it. Most use this system: on the side of the can it will list the different caps, something like this-
(triangle) 160 mfd
(square) 80 mfd
(half circle) 20 mfd
(no mark) 20 mfd

If I knew what I was doing I would show the actual symbols instead of (triangle) etc, but look at the lable and you will see what I mean. Now, the tricky part. Look at the bottom, next to the leads on that can. Just next to the leads the base will be punched out in the shape of, you guessed it, a triangle, a square, a half-circle-and one won't have any pattern. That's how you can figure it out without the schematic. Still, having the Sams is really nice.

There are several good places online to get caps at a reasonable price. Am I right that you are in Canada? justradios.com would be perfect. Radiodaze is another one I use.

Thank you very much Bgadow
I did notice those triangles and squares. But I could not find them on the bottom of the cap, so I gave up. But like I said before it's almost impossible for me to see behind there just yet. But I will get it all apart and do it. And figure that multi cap out :)
And yes I am in Canada and most likely will use your websites you suggested.
Thanks again

Thank you very much Bgadow
I did notice those triangles and squares. But I could not find them on the bottom of the cap, so I gave up. But like I said before it's almost impossible for me to see behind there just yet. But I will get it all apart and do it. And figure that multi cap out :)
And yes I am in Canada and most likely will use your websites you suggested.
Thanks again

If you look carefully at the bottom of the twistlok can where the live terminals are you will see that they protrude from the innards of the can through what is usually a brown bakelite or phenolic insulating material. On one side of each terminal (except for the "no mark" one) there will be an enlargement of the passage hole in the shape of a semicircle, square or triangle. Or the pattern will be embossed nearby.

Hello,

I found the proper RCC supplement for your TV, which appears to
go by the name Chassis T-109. Please give me a few hours to get
this stuff properly scanned. Bye for now.

Hello again,

Here is the schematic (pages 71 and 72), a chassis diagram (p. 41)
and a sample of the service data (p. 38). I am also enclosing the
index from the cover, though the image is quite dirty. I can get you
all the remaining pages if you want. Good luck.

P.S.: I will only send the schematic with this message, remainder
to follow.

As described in the previous message. Regards.

Canadian set - the schematic references 25hz AC power operation!

Canadian set - the schematic references 25hz AC power operation!

You're right, and this brings a question. A transformer type set designed
for 25-Hz will work fine on 60-Hz, with only improved filtering. What about
a voltage-doubler set like this one?

By the way, the actual set discussed in this thread is the 60-Hz model,
as evidenced by the fact that it has a single filter choke.

Damn wish I had looked here an hour ago hahaha.
I just ordered all the caps by tediously looking inside and turning them and what not. But it's all good. :thmbsp: And thanks for the schematic. Hopefully most of the voltages are near spec. I can't wait for those caps to get here. I'll tell you guys what happens as soon as I do.
And I"m pretty sure this set has two Chokes. And it also says on the back it's meant for 60hz.
I can't wait:D
Rudy

You're right, and this brings a question. A transformer type set designed
for 25-Hz will work fine on 60-Hz, with only improved filtering. What about
a voltage-doubler set like this one?



It would also have improved filtering, as the filter caps are approx twice the size needed.

Damn wish I had looked here an hour ago hahaha.
I just ordered all the caps by tediously looking inside and turning them and what not. But it's all good. :thmbsp: And thanks for the schematic. Hopefully most of the voltages are near spec. I can't wait for those caps to get here. I'll tell you guys what happens as soon as I do.
And I"m pretty sure this set has two Chokes. And it also says on the back it's meant for 60hz.
I can't wait:D
Rudy

Hello again,

Hope the schematic is readable. I can read the posted images on my screen,
but printing yields marginal text for me. Il you look at the chassis layout
(second image in post 57 above), you will see the chokes on the left
side, L-500 and L-501, the latter for 25-Hz only. On the picture you posted
earlier, I can only see L-500. By the way, you could trace the wiring to
this choke and check with your ohmmeter to make sure it is not open.
The nominal resistance (36 ohms) is given on the schematic.

T-301 near the top looks similar, but is the audio output transformer.
Good luck.

I know I have checked one choke. It came in at 39 ohms. The other one is closer to the middle(guess you can't see it in the pic), then yes there is a small trans for the audio output.

Tomorow it's all getting checked and the caps I ordered should be in. So the final word on this TV should be up tomorow. Exciting stuff

What may look like a choke is the vertical output transformer (T-400). It is
shown at the right of V-15 on the schematic. Next to it on the schematic is
L-400, the vertical sweep coil assembly part of the deflection yoke on the
CRT neck. The deflection yoke also contain the horizontal sweep coil assembly
(L-401) shown at the bottom right of the schematic.

OMG I got 300+ volts. But it scared me to let the tubes fully warm up because this 300 volts was higher than the original capacitor rating. Which was just 300v. Any suggestions on resistors to put in series with the diodes to lower this. I know I have some 25 ohmers kickin around.
I wanna see this thing glow!

If it's slightly higher (say, 320 - 340), and starts going down as the set heats up, it's ok - those caps have a 'surge' rating.

Or, you could get a Variac :)

Well I let it warm up fully(after I put in a 25 ohm resistor). And there was SOUND :music:
Yet still no picture. BUT I could definatley hear it sweeping.( The hissing ringing sound you get with all TV's)
But this is no surprise to me as I've only replaced 2 of the 4 large electrolytics. I was just eager, and I know its bad, but I couldn't resist.

So yea that's about it for now. Just keeping all you guys up to date.

And as for the screen not lighting up. Does everyone still think it is because of the caps or is it possibly dead?

Hello again,

Great progress indeed!

Here are a few things to consider, regarding the picture.

You must have high-voltage on the CRT second anode (the terminal on the
side of the CRT with a funny cable ending in a round piece of rubber-like material).
Testing for high-voltage without a HV probe can be tricky, but there are a number
of simple things you can check. You said you tested most of the tubes. Did
that include the HV rectifier inside the metal cage? With power off, and chassis
DISCONNECTED from the line, you can remove the cover of the cage, undo the
top cap of the 1X2A tube and pull it. Be careful when setting your tube tester,
this heater takes a very low voltage.

Also, in the third picture of your post number 19, you showed the rear side of
the horizontal output (=flyback) transformer. I notice that a big yellow capacitor
has traces of heating on it, it would be a good idea to replace it. There is also
another capacitor, a red tubular one with capacitance unreadable, connected
to the damper tube (12AX4GTA). See the resistor alongside this capacitor?
Il looks like it took a beating, the color bands are unreadable. It would be a good
idea to check this against the schematic and replace if necessary.

You may also want to take voltage readings at the CRT electrodes. If you trace
the wires from the CRT socket to the chassis, you should be able to find in particular
those that go to the cathode (pin 11) and grid 1 (pin 2). On the cathode,
according to the schematic, you should get +113 V, and on the grid you should
have somewhere between roughly 0 and +120 V, depending on the brightness
setting.

Also, be sure to measure the cathode voltage on the 12C5 audio output tube
(point V). This tube operates as a voltage divider to provide plate voltage
to many stages in the receiver. The nominal value shown on the schematic
is 132 V. This will confirm that most of the stages are drawing the correct
amount of current.

Good luck, keep the news coming!

REmember the crt acts like a capacitor at the h.v. spot.Take a srewdriver and short to gnd that spot to discharge the charge held by the crt.

REmember the crt acts like a capacitor at the h.v. spot.Take a srewdriver and short to gnd that spot to discharge the charge held by the crt.

Good advice, just be sure to slip the tool gently under the high-voltage
insulator on the CRT, in order not to scratch the glass.

It would be best to first attach a jumper to the screwdriver, connect
the other end of the jumper to the chassis, and then touch the HV
terminal with the screwdriver.

Wellll I did all the tests electroking told me to do.
The 12c5 at cathode has +122v after warm up.
Pin 11 of the picture tube has 120-140 volts depending on channel.( Tuned or not tuned)
pin 2 goes up to 70 volts then down to zero as you adjust brightness.(not exactly 120v)
The resistor you mentioned I also suspected of being shot. But with very close inspection you can still see a brown then green then brown stripe. JUST BARELY. And the resistor reads 127 ohms on my meter(Which is not the greatest, but it works) so it's kinda close. But maybe not close enough?
The capacitor you saw I will replace momentarilly I did order some of those charred brown looking ones. Also the one paper cap in the tuner circuit.

Oh and I almost forgot. I do think I tested the HV rect tube when i tested all the others. I'm pretty sure it was within spec. And I know that I am always very careful pulling things like that out and putting then back in. SO I'm pretty sure that tube is fine but if you insist I check again I will be glad to.

And the HV is in the thousands I am guessing. So it would probably blow my meter which only goes to 1000vdc.

Could those little paper caps really be stopping any picture from being produced?

I also have one more electrolytic I should change. But I dont have the exact replacement. It is 200 mfd. and I Have 100 and some 30's. I think I may just strap them all together till I get close. It's better than nothing right?

Rudy

P.S. What actually makes the picture tube glow. With these voltages should I at least have a dot on the screen already?

Hello again,

To answer your question, if you have correct voltages on the electron-gun
electrodes, you should get a spot on the screen, but only if HV is present.
Your measurements show positive results, but there are many more things
to check, and because of the distance I cannot think of all of them at once!

In my opinion, the next step would be to measure the cathode voltage
on the 12BQ6 (or 12CU6) horizontal output tube (pin 8). The schematic gives 3.6 V
across the 33-ohm resistor, which corresponds to about 110 mA cathode
current.

It gets hard to go much further without an oscilloscope, but let's see what
you get. Bye for now.

P.S.: for anyone just joining this thread, schematic is in post 56 above. Regards.

P.P.S.: also check voltage on G2 (pin 10) of CRT, this will tell whether the boost
B+ generated by the horizontal ouptut circuit is present. Be careful to use the
highest range on your multimeter.

Ineteresting.....Because there is no 33 ohm resistor hooked up to that tube. And the voltage I got across pin 8's resistor was only .5 volts. This is the one that you said looked burnt or possibly dead. and it supposed to be 150 ohms according to it's bands.
I will go look some more and also test the voltage at from chassis to pin 8 and see if i get the 3.6 volts it should have.
And I looked at the screen and I'm not seeing any bright spot. And I can clearly hear the buzz/whinning sound most crt tv's make. Is this a good sign the ht is working?

Cause if so..It brings me back to my original thoughts which is that the pic tube is dead......But I really hope not.

I did the test from pin 8 to chassis . Only .5 volts .....

Little more info: I made the other 200uf and put it in. Then replaced that yellow cap which was burnt. And still no picture.
And this scared me. But every now and then I hear arcing.....!This is during tube warm up and I always shut it off asap! It may be from my shabby work I did putting in the caps but boy was it scary. Usually it doesn't though

Ineteresting.....Because there is no 33 ohm resistor hooked up to that tube. And the voltage I got across pin 8's resistor was only .5 volts. This is the one that you said looked burnt or possibly dead. and it supposed to be 150 ohms according to it's bands.
I will go look some more and also test the voltage at from chassis to pin 8 and see if i get the 3.6 volts it should have.
And I looked at the screen and I'm not seeing any bright spot. And I can clearly hear the buzz/whinning sound most crt tv's make. Is this a good sign the ht is working?

Cause if so..It brings me back to my original thoughts which is that the pic tube is dead......But I really hope not.

I did the test frompin 8 to chassis . Only .5 volts .....

All right, let's not get confused here. Looking at the schematic around V-18,
I see:

cathode (pin 8) connected to ground through a parallel network of
R-453 (33 0hms) and C-439 (.1 mfd 200 V);

grid 1 (pin 5) connected to PC board through R-450 (150 ohms);

grid 2 (pin 4) connected to width control through R-454 (680
ohms).

If you found a 150 ohm from cathode to ground, that is strange, and
probably the sign of a previous botched repair. But maybe the 150 ohm
resistor you saw was R-450 above. Just as a reminder, the pins are
counted clockwise as seen from the bottom, starting from the indexing
tab.

The buzz means that the horizontal oscillator is running and probably
being amplified by the output tube, but until the circuit is fully functional,
no normal operation will happen. If you get the chance, please do check
the G2 voltage of the CRT. As I told you, this is fed from the boost
voltage generated by the damper tube (V-20), and is an indication of correct
operation of the sweep circuit. I bet this is not OK at present.
Good luck.

Sounds good. Gimmi half an hour maybe less

Ok and I have checked checked and rechecked pin 8. It does have a .1 mfd cap but its definatley a cap that has brown green brown bands on it. And it measures in at 126 ohms or so. It doesn't really look like it was put in by someone else, but who knows.

And another side not... There is a wire in the crt pins that connects two of them together. It looks like it is supposed to be there. And in the schem I thought I saw something that resembles this on the schematic so it may be right BUt just thought I'd put it out there. Its from pin 10 to pin 6 of the crt.

And you are onto something here. My meter gave me zero volts at pin 10 of the crt. 0v And the damper tubes seems to go through a variable resistor before reaching the crt, if I am right. This is for adjustment for vertical height located at the back of the TV.

"This brings me back to arcing. It seems the damper tube is connected to the same hv coil as the 1x2b.(I'm guessing that's how it boosts it) When I had the cage off I saw this transformer coil w/e it is. It sorta looked chipped The rubbery coating sorta flaked off. Maybe the arcing happened there somewhere causing some sorta problem with the damper tube causing my 0 voltage at G2. This is just a huge guess but I noticed there connected through this so it could be true. " This is a BIG GUESS

Hello again,

Maybe the cathode resistor is correct after all, but if you only measure 0.5 V across
it, it means current is only 4 mA, definitely low.

(What I meant here is that sometimes component values are changed in production).

The jumper you see at the CRT pins connects the focus pin (6) to either pin 2 or
10, as selected for best results when installing the CRT. This is no problem.

I think I will call it quits for today, don't give up hope, the diagnosis will come up,
and the cure will follow! Let me know what you find out, but as I just said I won't
be replying until tomorrow. If anyone else wants to join in, I trust you're welcome.

Yea if any one has ideas or things for me to check just say it. Nothing sounds stupid to me and it's all worth checking.
And ElectroKing your help is greatly appreciated. And yes we will tackle this problem another day still :thmbsp:

Oh and if anyone is having trouble reading the schematic open it in paint and invert the colours. It helps.

New Info: The damper tube produces 350 some odd volts. Then it goes down through a 270k resistor(that reads 350k on my meter) and goes directly to G2(pin 10) of the CRT. At the Crt the voltage on G2 is 250 volts.
Tell me what you guys think. I must have fudged my first test.

Two more ideas, and I promise I close Audiokarma for the night!

1 - Capacitor C-440 (0.068 mfd, 600 V) just below the damper tube on the
schematic is a filter for the boost voltage rectified by the damper. If
it leaks, it may lead to the loss in voltage observed. This capacitor
has a low capacitance here because the frequency is high (15 kHz, not
60 or 120 Hz as in the power supply).

2 - With power off, the main winding of the flyback could be tested for continuity.

From top to bottom, the terminal numbers and resistance values are:

7 (cap of HV rectifier)
460 ohms
6 (cap of H ouptut tube)
24 omhs
5 (cathode of damper)
4 ohms
9 (end of winding in deflection yoke)
31 ohms
3 (end of C-440 not connected to plate of damper)

Note that the first section has higher resistance because it has many turns;
it is the part of the transformer that generates the high voltage pulses
to be rectified by the 1X2.

If the readings are approximately OK, the transformer is probably still good, even
though there may have been some arcing in the past.

Good night.

Do you hear a raspy low frequency sound? Like a little motorboat motor in there? If so, the vertical is working and you no doubt have at least functional horizontal.

Don't overlook the obvious - the brightness might be down on the TV :)

You can't, unless you can easily (safely!) see up into the HV rect, see it glow normally. BTW, if you get an HV *pop* when you discharge the CRT, you no doubt have HV, which is going to be on the order of 12,000 - 16,000 or so. If you've got a hissing - like a gas leak - coming from the HV box, you have HV, and a good amount. Shut the set, discharge it well, and CLEAN THE HV BOX. Dirt might cause leakage, arcs, flashovers, and scary things that can be bad for the set.

Don't ever measure the horizontal output tube's plate - there's a big pulse riding on it.

BTW, sounds like you're gonna need an oscilloscope - get one that can go over 10mhz. They're cheap and a great investment.

Ahhhh I was checking those resistances earlier. They seemed alright but I did not check from 7-6 or the nine one. So I will do this.

And this has been driving me nuts. On the schematic you sent me v-2 is on the left and v1 is on the right.
But on the back of the TV in its tube diagram V1 is on the left and v2 on the right. SO I checked the tubes and surley enough they were as the schematic you sent me v2 left v1 right. BUt on the back of the tv (Which had to of been right for this model) It is reversed. SO if the tv's original cover does not lie. These tubes are reversed. And need switching.
I will put a picture of the tv's diagram momentarily.
Also one of these tubes was a weak one. And if they really are in reverse maybe it is because the heater voltages were different causing earlier melt down.


Hmmmm... no motorboat noises. But I will listen harder.
Haha I also thought the brightness might be the cause. So I fiddled with all the controls and it just wouldn't work.(Bummer)
But cleaning it sounds like a good idea. It was very dusty. I'll blow it out tomorrow when I am checking the coil resistances

Pictures in 2 minutes

check it out

Its blury but you can still see my point. It is reversed. Should I switch these tubes around?

The other schematic showing how my tubes were installed is on page 4 of this forum.

Picture 2 in post 16 shows a big hole in place of the tuner in the upper left corner
of the chassis, because the tuner is mounted on the front panel in your particular
set. The 5AT8 is the tube that goes nearest the tuning knob. So I assume there
is some kind of discrepancy between the rear cover and the actual layout. Tell
me if this sounds OK.

All the tubes use the same heating current (600 mA), so reversing them is
unlikely to have caused damage.

Yes you are dead on. Its mounted near the front with all the knobs. And it was in correct. I tried switching them and no sound. So I guess that solves that.

Oh and after letting it warm up in the dark there was one tube with a blue cloud. But it went away(very bottom right) And I smelt something burning. Not burning insanley. But I can smell it. And I noticed a resistor that has black goo near the leads that come out of it.(This was near where I thought the smell was) Its bands were green blue brown. And it has 650 ohms of resistance instead of 560.

I will turn it on and smell some more...

The smell is definatley coming from the middle. And this resistor is almost the only thing there. It is hooked up between the two large upper capacitors.
I also tried a trick some one mentioned at the beggining of this forum. A fluorescent bulb near the ht line that goes to the side of the CRT. The bulb did not glow :(

I should have thought about it, if you had sound, the tuner could not have the
tubes installed wrong!

By all means try to identify this resistor: to what tube pins or other points is it connected?

P.S.: there's much more fun in troubleshooting than in demolishing, don't you think?

Ha ha ha yes. This is definatley more fun that putting another pile of junk aside for me to use in the future. I can hardly sleep trying to figure this thing out.
In other words. "I just can't get enough, just can't....."


and more specifically the resistor goes from 30 mfd to the 200mfd. These are the larger ones at the top.

Hello again,

Regarding this 560-ohm resistor, could that be R-451, connected to L-400,
at the right of V-15? If C-443 (an electrolytic) is leaking, it may cause
the resistor to heat up.

How many hours has it been since I told you I was quitting for the day?
Good night!

So it is R-451, but the parts on the schematic are far apart:

The 30 mfd is C-443 as I told you.

The 200 mfd is C-502, the upper capacitor at the output of the filter choke
in the power supply. You can follow the long wire marked 264 V running at the
bottom of the schematic.

Tooo many. hahaha I am quiting to. And I will have something to say tomorrow. I think about this stuff in my sleep.

More tomorrow folks!

hehehe a tech pow wow... love it :D

Steve

So I was trying to look up if the crt could be dead. And have no glow, picture or anything. I never found my answer, but saw some stuff on LCD repair. And I remembered a 5 inch LCD I bought in gr. 7-8. Of coarse though it stopped working. Much too soon of coarse(maybe in a year or two). And it cost 200$. I tried my best to asses the problem at the time. Blown backlight dead something else expensive(and probably non existent for that lcd).
It was a bummer. I begged my parents for it. And they spent that 200$ for me. And then one day it just didn't work.....:(
(I didn't even own a ps1)

Well today I was still in the fixin mood. So with all my new knowledge since gr 8 I went to tackle it again. This time I did not assume it was broken. I assumed something simple had blown like a diode that blows when you hook up polarities backwards. Nope all diodes good though.(This is also all surface mount stuff...way waaaay smaller than tubes smaller than these letters you are reading) And then I saw it. Something not called R-37 or C-12 or T-1 (Resistor Cap and Transformer) THERE WAS AN F-1, A FUUUSE!!! I shorted it out with some metal and it came back to life.And I almost s@!T my pants.

So the moral of the story is. Don't throw stuff away you think is done for. You might just figure it out with all your new tricks and knowledge.... 5 years later....

AND I FIXED IT BOOYAH!
made me feel good

now back to 60's technology

I found a perfect (Wire wound I think) 560 ohm 2 watt resistor. This is pure luck. But I'm gonna put it in there tomorrow.
And also I need reassurance that the picture tube is not dead. Even with all the progress so far a dot will not even show up on the screen....?

New Day,

Also I thought for sure I had H.V.. But after putting a fluorescent bulb near the H.V. And trying to discharge it twice and hearing no spark as I did it. I'm guessing the HV is gone. I checked all the resistances ElectroKing had mentioned they check out fine. So the problem does not lie there.

I'm going to replace all the film caps near the HV area and also that one 560 ohm resistor AND then check that the 1ax2b is properly connected to its socket. AAAANNND does anyone think a dirty faulty button connection (The little cap that connects to the top of the tubes) could be causing such a problem.

And the results of that were:

The 560 ohm resistor IS burning up. Something drawing current from that resistor is either underbiased or just not working right. But from the schematic I see it is hooked up to the plate of the vert d/f tube and this tube is not biased in any way, its cathode is just grounded. Any ideas?

HA! HA! HA! more news: The vert deflection tube is the same one I saw glowing blue yesterday night. In the bottom right. If that helps any

OK I AM thoroughly CONFUSED. LIke a monkey in space.
I was looking over the the wiring of this tv. And it isn't an exact match to the schem. OR this TV is wired up very wrong. I just don't know.


According to the schematic the damper tubes pin 5 should be hooked up to the power supply.(Point 1 for 60hz operation) Instead in the TV pin 5 is directly connected to pin 1 of the horiz output tube.

PIn 6 of the damper tube is also directly connected to the 60hz line right from the wall. It then goes (via 25 ohm sand resistor) to pins 7 and 6 of the horiz output tube.

And pin 3 of the damper goes to Lead 5 of the HV rect flyback transformer thing.(In the box) Pin 8 of the damper goes to 3cb6. And pin 7 of the damper goes right to pin 2 of the horiz output.

What confuses me here is that the horiz output should be connected to the high voltage Through a 8 k resistor then an adjustable one (Those resistors are there) But it goes from pin 5 of the damper instead of the Power supply Or 256 volt line.
And pin 5 of the damper should be hooked up to point 1 on the power supply(Which it isn't)
I AM STUMPED. STUMPED I TELL YOU

If you would like I will take detailed pictures then edit them on paint to show you what I mean. And point things out

P.S. The voltage on v15's plate should be 220v and it is much less than that. I am trying to give out as much info as I can here

P.P.S. No it is wired right I am just stupid. THe wire was hidden behind a large paer cap.The 256v goes to the 8 K resistor. Then it also goes up to the damper tube(pin 5)

UMMMMMMMM!!!!!!!!!!!!!!! I think theres picture folks


I turned it on.....My plan was to test for 256 volts. And just before I did I turned all the adjustment knobs to center. Turned it on and it started making some noises that scared me. And then flash! I turned it off so fast. You can't even measure that amount of time(Just kidding, but it was quick) This scared me. ALOT

But this flash. I do this think it was the screen. So I tried again and it flashed again. But by this time I was shaking so off it went again.

I THINK ITS WORKING!

OK so i tried it again this time with intent of leaving it on and nothing. No flash no nothing. Back to dead. This is bothering me


The width control. This resistor is not functioning properly I think.
With my ohm meter hooked up to it set on 2000k I can get it to read zero And i can get it to read Nothing its either zero up to 12k Then It says there is no connection.And this happens within 1/8 of a turn. After turning the TV off I actually got some picture to show up. I wouldn't call it picture though it was just light.

My question now is. Would this variable resistor screw the whole thing up. Cause it kinda seems like it did.(it is the width control one hooked up to horiz output tube.)

SO will it need cleaning or will I need a whole new one.And if I do need a new one, ElectroKing you will have to tell me what it is I cannot make it out from the schematic.
Thanx
Rudy

Hello again,

Sorry, I'm very busy with work today and tomorrow Friday, then I must go away
over the weekend. The fact that you got 'something' on the screen (even in a
transient fashion) means there was high voltage at some point. You're on the
right track as long as you are studying the schematic carefully and noting the
(hopefully small) differences with respect to actual circuit construction.

You can possibly clean the variable resistor with a proper cleaner fluid designed
for the purpose. If there is a hi-fi or electronics store in your area, they might
be able to provide the right stuff.

I will take the time to study your latest posts further when I get back on Sunday
night. Don't lose too much sleep, keep up the careful approach and you will
make progress. Bye for now!

P.S.: pin 1 of H. output tube is unconnected, it is just used as a tie point.

Alright well enjoy your weekend I will to. And I'll sleep :thmbsp:

Yea I'll clean The pots out tomorrow Or something like that. More fiddling
And hopefully she comes to life. And it sounds like theres a really bad gas leak when I turn it on. And interesting is that the picture mainly flashes when I power it down. Or maybe I'm just not giving it long enough.

Oh hell yeah the width control could kill the picture. It's controlling the voltage at the horz output tube's screen grid. Without a good voltage supply there, you won't get much sweep, and won't get high voltage. And it's a 1 watt pot because it's drawing good current. If the cap after it is leaky or shorted, you'd get issues too.

As a temporary check, get a 1 watter about 1/2 the value of the pot, and jump it in place. The schematic suggests about 150 volts there, but it could be a bit more or less - it's really not a critical value.

The blue cloud tube, I'm gonna bet was the vertical output tube (12B4), and that's 560 resistor burnt up because you've got a short in there or it's gassy, or here's bad things in veritcal land. Here's a better idea than waste the resistor or toast a transformer or coil: Leave it disconnected for now - you'll have a disabled vertical section, but that's ok. Just keep the brightness down so you don't burn a line on the CRT. Concentrate on the horizontal section - it needs to work right first to make vertical work too (the vertical get's a boost from the flyback!).

The horizontal will come up weakly, but once it gets boost built up, it'll 'kick in' rather quickly and you should have high voltage along with it. That's when things get interesting :)

Well I don't know the value of this pot as of yet. Maybe it says it on the back. But I cannot get it from the schematic.

And the Hv does work when this Variable resistor is set to have some resistance.(And I am observing the voltage this resistor is dropping with my voltmeter. To make sure its not the full 280v like it was before, it's usually 20-40 volts)

And another question is how gassy should this TV be sounding when the HV is working. Cause I am usually overcome with fear when I hear this tv fully power up. Sounds like a cap is about to blow up in my face...or something. But it's definatley a gas leak sound.

And heres the real kicker. The tv warms up makes gassy noises. But no picture shows up. So I get scared after about 10 seconds of listening to the gassy sounds and shut it off.

This is when the tube finally shows some life. A large sweeping square shows up.
I got one good look at it.
It was a large square that took up the whole screen at first. And then shrunk rather uniformley, in the shape of a square. And this gives me hope. Cause that would mean that the horiz and vert are working...correct?

BUT WHY does it only work when I turn it off? Could I just need to hook up the antenna or something like this? No signal to make picture?

First I will check all the pots see If I can get them working. If not I have some kicking around but I'm not sure how much current they can handle.
They are larger than the ones in there, but that could easily mean nothing.
And earlier today I changed all the caps near that area. Cause I obviously had no HV.

More news tomorrow and all the help is appreciated guys:thmbsp:

A slight terminology issue: "gassy" refers to there being gas inside a vacuum tube. (where there is supposed to be, well, vacuum!) So that vertical tube might be bad. They sometimes glow funny when that happens. Could also be caused by something like a bad cap in the circuit, which is almost guaranteed in a set this age.

The sound you hear like a gas leak is almost certainly arcing (corona) somewhere in the HV line. It will be somewhere between the flyback and the HV connection of the picture tube. Could just be poor insulation or something too close to ground. One way that can work to find it...and this could take some bravery! (don't worry, it won't reach out and grab you from a yard away!) You need to turn the tv on in a dark room and then look at the chassis while it is making that sound. You likely will see where the problem is-a constant blue spark is common. If you find it, turn the set off and try to figure it out from there. Good luck!

The pot for the width control. I've been staring at that schematic crosseyed and with glasses and from across the room. And I think it says 15k does it not?


As for the gassy tube I tested it and it tests ok and with no shorts. Does that mean it's alright...ish?

And your dark room idea sounds like a very good idea. I did start it up last night in the middle of the night. (I have been working on this TV outside, it had alot of weird dust) And I didn't notice any arcing but I wasn't exactly looking for it either. That will be done tonight.
And from what I can see the HV line comes out of the box then right back to the side of the picture tube. It doesnt seem to get very close to ground but I will insulate and move it further.(Would electrical tape help?) The hv line also looks like some one burnt it with a soldering iron. Like a dip in the insulation, I'm sure you know what I am talking about. AT this same point the wire is tied in a large granny knot. It is not tight but rather loose. I thought this might be because the cord was just a bit too long.

Any suggestions??

Rudy

Alright I have a 5k pot that looks like it can handle the current.
But I also have a 20k that is fairly small but looks like it might be able to hack it.(doesn't look cheap)
The 20k is 1.5 cm in diameter and 8mm wide. Anyone think it wouldn't burn up?

The 5k is 2.5 cm by 1.2 cm So I know it will handle it but its only 5 k. Not 15K(which is what I think it should be)


And I didn't post this message when I wrote it so the 5 k is already in there for testing purposes. But if some one thinks the 20 k one will work I will switch it.

We have horizontal folks. The tv with the new pot is showing a line that goes down the middle of the screen. Horizontally. The gassy sound has gone away. Maybe due to the new pot or electrical tape I wrapped around the HV line. And still when I turn it off it goes over the whole screen Then disapeers. I'm not sure if it is doing the square thing anymore though. It sorta seems like it But It's to bright outside to really tell. I HOPE TO GOD I DID NOT FRY SOMETHING.

Any one have a guess as to why the vertical would kick in just as you turn it off?

Also the 560 ohm resistor appears to no longer heat up. And checks in at 530 ohms. Amd from the resistor all the way to the vertical ouptut tube there is 1240 something ohms of resistance.

Like a monkey in space.
Reminds me of an old space sci-fi movie, where at the last minute, they substitute a crew of humans in place of apes on some space mission. But they didn't have time to modify the banana dispensers...

Anyway

If you can't find a good high wattage pot, you could just use fixed power resistors of the same value once you identify what the setting of the pot needs to be. You can also parallel higher value resistors to fine tune downwards the resistance. But don't hand poke around with a resistor in your fingers, the horiz circuits can "bite you in the ass...". Turn the set off and tack solder it in, to try it.

If you need to replace the very high voltage cable feeding the side of the CRT, you could obtain such from a junked computer CRT monitor. Those are even better in that they come with a rubber suction cup like cover, to protect you from the high voltage at the picture tube.

Junked computer monitors eh?:scratch2:


I went to look at it again before I went for a smoke to celebrate my good progress and it seems like the whole screen is being sweeped. It is still much to bright out to really tell but thats what it looked like to me!
Can't wait till dusk!


Roughly how long should it take for this tv to warm up?

The screen is on:banana:

But still showing no picture. And its not really fuzz either. More grey than anything. Does it need to have an antenna connected. Or something in order to get picture. Or do I have more work to do?

ALso I am pretty lucky after warm up voltage at the horiz output tube is 150 -158 as stated by the schematic. So hopefully that works till I figure this whole. No picture thing out.


Could this possibly be a problem with worn or dead tubes??


Woooaaah. Just did another test watching from the back The tube in the bottom right v15 turned blue. But then went back to being fine. Should I worry about this? and would a gassy tube still check in fine on a tester?

I'd be looking to replace that vertical tube, frankly.

At this point, you'll want to replace ALL the paper/wax capacitors, and I bet you'll see a decent raster.

Take some time, clean that HV box and around the CRT on the back by the 'suction cup' for high voltage. Get those leakage paths out of there.

I'd be looking at CRT voltages at the socket, see if they match the normal ones for that tube type.

Getting a raster means you've got working sweep, working HV, and a good CRT. You should clean up the horizontal and vertical circuits - get the caps replaced, check the resistors out, make sure it's behaving right. Then get that IF section and tuner going. Don't touch ANY adjustments for the IF or tuner stages (beyond the 'fine tuning' available on the channel knob).

Get an isolation transformer, and look at getting a variac, too, maybe. Old TV sets have a way of finding you once you revive one :)

Antenna - the better, the better.

Sweep is what TVs are all about - get it working right first, and everything else falls into place.

I forgot all about the fine tuning, I'll try it out tomorrow.

And here's what the tv can do at this point. For everyone that doesn't wanna read 7 pages of this.

The tubes all warm up. V15 the vert. output tends to glow blue slightly then go away(It also does not get overly hot).
The audio output tube also arcs inside sometimes during warm up.
The audio works. I can get voices and commercials and what not.
The crt lights up and gives me a big'ol grey screen. Switching channels to a tuned one "will" change the way the screen acts. Sometimes getting darker or brighter.
There is no fuzz/snow like a normal TV. Just grey. With very slight static. No snow.

Also (this worries me) when it turned on originally the upper half of the screen was full of "grey" lets call it.(Light) The lower half was "half filled" with "grey" then there was a solid white line, Then black till the bottom. Adjusting the vert height got it to fill the screen. But my concern is that, the bottom deflection yoke(I don't know terminology too well) is burnt or something. Causing the bottom half to not fully spread downwards, wild the top half is already off the screen.
Is this making sense to some one? And is this even possible.

And I did check the voltages at the CRT. The brightness voltage was off. Should have been 130v but it only got up to 70. But this was when picture was not working. The tv's brightness can make it go white at this point. So I think it works.

One more question is what does vertical linearity do for the picture? It's an adjustment located at the back.

P.S. Schematic on page 4 and pictures tomorrow showing what I get

The "gassy" sound you were hearing was likely high voltage arcing and leakage. It is a "hsssssss" that may sound like gas leaking from a crack in a pipe or cylinder. If the HV leakage is severe enough it will keep any image from forming on the screen at all. As the leakage diminishes then whatever image can show will show on the screen. Perhaps the warming of the set has driven out the moisture that enabled such discharge to occur.

As for the gray raster with no snow you may want to examine the sound output tube--believe it or not. A lot of these old sets used the sound output tube as a series voltage regulator, where all the picture IF stages and the tuner would feed off a 130 volt supply right off the cathode of the sound output tube. If the tube is flashing over then it is possible that it is weak or altogether bad, or that the electrolytic capacitor on the 130 volt line is shorted or severely leaky. Either way the result is that there is low or no 130 B+ supply to the tuner or the picture IF stages. Sometimes with this problem one can turn the volume control way down, and then turn it up rapidly, and the raster will suddenly brighten and produce snow for a brief moment. The output tube can be weak enough to supply insufficient B+, but still have enough life to produce sound.

(Edit) Reading your last posting where you get sound but no picture at all leads me to want to re-examine the video amp stages.

The vertical output tube needs to be replaced. the blue glow indicates a gassy tube (air has gotten inside the vacuum.) If you're hearing sound but only seeing gray, there is a problem in the video amplifier section. Could be a tube, but more likely some bad capacitors. If you haven't replaced the paper coupling caps in this set you can't really judge its operation condition or really begin to troubleshoot until you do.

The vertical linearity interacts with the vertical height adjustment to make the picture vertically symmetrical and not too stretched or compressed at the top or bottom.

Alright well I have the tubes I need.(Courtesy an AK member, Thank you very much)

So I can switch them out, I am just concerned that I may destroy the new tubes I put in. Roughly how much bad operation can a tube handle. Will they be destroyed within minutes. Or should I not worry.

And yes I was getting arcing. From the top of the HV coil. I mentioned it was chipped there before. Last night I finally saw it jump from that point to the frame.
Here was my simple solution to add insulation. Hot glue gun. Its rubber, rubber insulates and it's fast and easy. Maybe some one else will find that trick handy.

Rudy

THe hot glue gun is ok, but most will use a silicone RTV designed to work around HV. They usually stops the problem in the short term. Make sure the HV cage around the coil is clean and without dust. Dusty cages will cause corona discharge and arcing.

If the tube is glowing blue - its usually the fault of the tube and not the support components. However, arching inside tubes can be either the tube or the supporting components. You're gotten this far, I would really consider replacing the capacitors in the set. They are not expensive and it will mean that in the long run the set can be operated in a reliable state.

The dust I have cleaned off with a toothbrush :) The cage I washed. It's spotless.

I've put new tubes in where needed. And am going to test it out. If I see blue or arcing the caps will be changed. I changed all the electrolytic already. But some are axial not radial.
The coupling caps looked like inductors to me. It wasn't untill after I made my cap order I realized they were coupling capacitors. They are radial type. Not electrolytic. They look good but....yea your right They probably need to go.
There's also a black beauty near v15. I suspect he MUST go. But I can't figure out its value. It only has three lines on it. Starting from the end with a blob of solder It's blue orange brown. And very faintly they're may be two more brown lines on each side of the orange band. Any one know what value this may be. Cause I don't think its coincidence that the tube that glows blue has the only bumble bee cap in the whole circuit right next to it.

And here in Winnipeg caps aren't cheap!! I went to a place some one told me it was cheap to buy from. It was $17 for one electrolytic rated at 450 volts and low mfd.
Another place offered me electrolytics for around $8 a cap. I had to order mine online in order to get my money's worth.

Definatley works better. There is no blue. There is no arcing in the audio output tube. And you can actually hear stuff better. But still there's no picture. :no:
I guess it's time to get some more caps. Bummer

And cathode of the audio output is at 144 volts according to my meter. 12 volts too high. Any suggestions on how to get this down? Or no worries?

12 volts isn't gonna make a huge difference, or at least shouldn't - measure the cathode/grid voltage and see what it is. But if you get decent sound, I'd not worry.

Trace out the BB's wires and see where they go - you can use that to figure out where in the circuit it is.

As long as you're getting a raster on the CRT, you've got the basics and it's just capacitor replacement and checking things out. Don't worry that you're not getting a picture - it's in there you jusdt need to find where it's getting lost.

Seriously, at this point, you're gonna need an oscilloscope (and an isolation tranny to keep from blowing up a scope). With a 'scope, tracing out these issues is really easy and fast - you SEE what stage the video gets lost at, or what the vertical signal looks like, etc. A used one shouldn't be too much, and it pays for itself fast.

You've got a TV set that's got the basics working, it just needs some cap replacement and some targeted diagnostics. But unless something's grossly wrong (and there shouldn't be at this point), you'll get a picture if you just keep at it.

Anyone have a spare oscilloscope...?

Ha ha. Yea I've always wanted one but brand new they are not cheap. Used though could prove to be very cheap and useful. And an isolation transformer would just be 120 ac to 120 ac correct? Just stops it from getting a full 15 amps if it shorts out right?


And I looked on fleabay. Would something like this be good enough
http://cgi.ebay.ca/Oscilloscope-B-K-Precision-1403A-scope_W0QQitemZ250299923076QQihZ015QQcategoryZ3284 QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I have 40$ for anyone who has one maybe more...

No, an isolation transformer gives you isolation from the power line, which prevents the chassis from being 'hot'. It serves a very important safety function when servicing series string TV sets, especially when you have test equipment involved.

For a scope, look for an ability to go up to 10 Mhz or higher, calibrated timebases and voltage scales, and a 10V per div input range.

Is the way the bottom of the screen is black normal to an extent?

Or could a coil be fried. I checked the orange and green wire coming from the bottom of the crt. (I figured they were responsible for the bottom vertical half of the sweep) Ans it had 700 ohms which I think is right.

Some sort of the other adjustment maybe. Yoke or something.

This picture was taken tuned to a working channel.

The bumble bee was hooked up to pin 9 of v15. The only one hooked up to pin 9 was one that said . 0547. Seems like an odd value to me. Also the .15 and .1 caps to the right of v15. How important are these two caps. Will they make a large impact.

And is there any way to test a cap just with a voltmeter? Doubt it but I figured if anyone knows it's one of you.

The condition you see is called fold-over. The bottom part of the vertical scan has folded over on itself causing the black bottom and bright band. Its usually caused by leaky or shorted capacitors, occasionally a resistor that has gone up in value. Look in both the vertical oscillator and output section.

You would have to pull out the cap to test it on an ohm meter. You would also need an ohm meter that put out a high enough current to test the cap for leakage. Since you have to pull it - just replace it.

Trust me on this. Replace the coupling caps in this set and most if not all of your troubles will disappear. I wouldn't even bother to waste your time further. The set basically works - so why not just restore the chassis completely? I don't understand why you might want to have to keep servicing it in the future when another problem pops up from leaving original parts in. :dunno:

Ok, you've got poor vertical linerarity. No surprise there. I wouldn't be looking at the yoke, yet. That'd be far down on my list.

Rather:

* Go through the vertical section. Replace ALL paper caps, and check resistors. Make sure the voltages into the Vert board are right (+- 10% or so).

* The black bar at the bottom? Centering :) That's what those centering rings on the yoke do.

* Don't finger the yoke, it's not likely to be bad if it's not open ad the resistance is close to the listed value.

You've got pretty good horizontal and HV and the CRT looks decent.

That bumble bee is a .0047 If it's leaky, it could mess up your vertical pretty badly. The .15 could be a problem, too. The .1's not as critical, but replace it anyway.

The .047 and other caps on the vertical board should be replaced, too.

With these caps replaced, try adjusting the height and lineararity controls to see if you can get thee raster looking right. They interact with each other. Height controls the height, and linerarity controls how evenly it sweeps. In your case, it's going real fast at the top of the screen, and slowing as it gets to the bottom. When everything's right, it'll adjust to be a smooth sweep all across the screen, and the picture will look right.

Once you get all that working good, you can attack the picture issue. Remember, the sweep sections of a TV set use the most power, and if they're not working correctly, everything else is moot.

You said you were getting sound. How strong is it? Is it staticy, or does it 'pop' a lot? With this set, a good strong sound from a TV channel should give you picture, too, unless something's messed up in the video amp's output wiring.

Well yea that's why I'm confused. The sound is very strong with the new tube in. I have a very inefficient speaker hooked up to. But the picture just isn't there. I've tried adjusting things till the screen is completely covered then adjusting everything else to get it still. You can not get it still. But the screen can be covered. And can look Grey. But with a channel its all over the place. And you can't see any distinct picture at all. Until you've stared for to long and start imagining.

The sound is not perfectly clear, I guess. But it is descent.

And I have that .15 to put in. So that's good.

And I am curious. The height control. IS(?) it supposed to be 2meg on one side and 6 meg on the other. Because this pot does not check in equally on both sides. Its over 2 megs on one side so my meter says its not connected. Maybe this my problem I already had one bad pot, That caused no HV.

I also found a 22k resistor that goes to the cathode of the 3au6 v12 that only checks in at 15k! And I should have 22000 ohm res.
And I have a 22k resistor. But it's a newer type. The bage very very light brown ones. About a cm long. Can it handle a watt?
Also found a wax covered mica. Real skinny and flat. It shows 00 resistance. So I will start with that and the BB. Also the resistor if it can handle the current.

And any one have a say about that vary pot?

The area you may need to look at more carefully is the video amp stage. Is there a video signal at the output (plate) of that tube....? If so then trace along the network between there and where the signal reaches the cathode of the picture tube. Possible culprits would be any defective component in the network of peaking coils, capacitors, resistors and whatever.

Also--heaven forbid--is the possibility of a heater-to-cathode short in the picture tube itself. Although in a series-wired set this would likely lead to a raster full of horizontal hum bars....

What would horizontal hum bars look like?

That bumble bee cap must have been a replacement or something.(Its the only one in the whole set) It says it is rated at 60000pf If I did it right. (From the point with solder,Blue, black, orange, black, brown) This would be .06mfd.
Which makes me ask again. Is the cap just above v-15(12b4a). Rated at .0547(or is that unheard of) or .0047 as previously stated. I will trust your judgement over mine. And I cut it out already. So I need to get a new one.

So I went to Radio Shack and did not find anything useful. HAhahaha...Figures. But I found one descent thing there. A new voltmeter. This one can test hz and capacitances. Paid 44$ and I'll be able to right it off as a work expense when I start work as an electrician. So score for me.

That bumble be came in at 15 nf. This is wrong. Wrong as can be. So I made a .544 up. With two .022 caps and a .01 :P
I also did the .15
Testy testy time:
Also still wondering about the variable pot. Is it an audio tapered one or something. Because with my new tester it goes up to 500k then on the other side It goes up to 3 megs then says there's no connection, also across the whole variable pot there is 13 meg . Change it? for what?

Minutes later
The picture is still roughly the same. Maybe a bit better. But no sudden people on the screen.
And man you can feel this thing power up. Makes me feel really wack.

P.S. The pot is just screwy. On one side it won't even show 0 resistance . It'll go as low as 315 k then up and beyond 2 megs.

Hello again,

I don't think this has been suggested before. The cathode current of
the 12BY7A video amplifier is supposed to go through R-221, the contrast
control potentiometer. If there's anything wrong here, no video signal
will get to the CRT cathode.

With the set off, just pull the 12BY7A tube, connect one terminal of
your ohmmeter to ground and the other to pin 1 at the tube socket.
While rotating the contrast control, you should get a smooth variation
between 0 and about 500 ohms. If this is OK, fine, otherwise the
control should be cleaned, replaced, or temporarily replaced with a
resistor of about 250 ohms.

Once the previous check has been completed, you may reinstall the
video amplifier tube, power up the set and check the DC voltages on
the tube: +178 on plate (pin 7), -2 on control grid (pin 2) and +161
on sceen grid (pin 8). Note that schematic seems to be indicating the
-2 volts on suppressor grid (pins 3 & 9), but that does not make sense
as this grid is grounded. I do believe that the -2 applies to pin 2.
If anything is odd here, get back to us and we'll discuss.

If you have good sound, it means that the problem is somewhere
between the video detector (V-5B) and the CRT cathode, and
things are not that complex in this area. Bye for now.

Sounds like a plan.

I will also be changing the horiz output tubes cathode resistor.
It checks in at 120 ohms and should be 150. Might this help some other voltages get in spec. Such as the 3au6 and 3cb6.

how are you checking the resistors?

If you measure them while they are in the circuit, you almost always get a lower value because of the resistance in parallel with that one (tube elements, caps, etc) Unsolder one leg of the resistor and then check it. You'll find that the values will be MUCH different.

Usually when resistors begin to fail they will go UP in value, not down. Chenging the cathode resistor in the HO circuit will NOT change the voltages in the IF stages. If voltages are low its due to a power supply problem or something pulling down the voltage in the IF stage like a shorted capacitor or tube.

Do you have a tube tester?

Yes I do have a tube tester. B&K model 606 tests if its good or not, shorted, or if its grid is leaking/or gassy it claims. It works but I am not sure of it's accuracy(needs fine tuning I'm guessing but it works).

Most of the resistors I have checked have capacitors or something blocking them off from any parallel paths and what not. Or would this still be way off.

The 470 ohm resistor that goes to pin 2 of the video amp checks in at 530 ohms

The path from v5 to v6's first grid also checks in OK. Although I noticed there is no resistor in parallel with the second inductor after pin 8 from v5.(Change in production?)
Oh and the contrast 500 ohm resistor is fine. It makes the screen brighter and duller as of right now.

And the horiz. output gets it's voltage from the flyback trans. At the bottom it has connections 1 and 2 that go off to the left and go to the plates and cathodes and grids of some of the tubes? Does the current the horiz output draws affect those voltages.Or are they not connected in that way.

Voltage Readings soon tomorrow




Hehe Racoons keep waking my dog up then she starts barking. So I go outside with a bucket of cold water (and it's already cold out) and..well.. you can imagine the rest. They Don't Like That.

The winding with terminals 1 and 2 of the flyback provides pulses to the circuitry
that synchronizes the horizontal oscillator frequency to that provided by the
sync pulses in the received signal, in order to achieve correct horizontal sweep.

Well I checked the voltages.
Pin 8 had 170 .
pin 2 had -220 volts , measured from grid to ground.
pin 7 had 161 volts

Sort of the reverse of what it should be
Although I did not adjust the contrast at all during that test. Afterwards I tried again on pin 7 and could vary it beyond 180.

What about that grid though?

...
pin 2 had -220 volts , measured from grid to ground.
...
What about that grid though?

If you really got such a big negative voltage at the grid, no wonder
the tube doesn't pass the video signal. Are you confident about this
measurement? It's hard to believe.

Did you check the contrast control operation with the tube removed?
I guess so since you proceeded to measuring these voltages.

Yes the 500 ohm pot is doing just fine. So I did the other tests.

And sorry It's this new tester I got. It said -200mv (still getting used to it). But shouldn't it be -2000mv.

What should I be checking to get this right?

The cap marked 400v should be .1mfd

Well, all the discrete components that are connected to V-6, in particular R-222
R-231, R-229, R-232, C232. The capacitor C-232 is only marked 400 V,
without capacitance, maybe you can locate it on the PCB and identify
it. You might bridge it temporarily with a similar one, without removing
the original. Be careful with those old PC boards, they were fragile even when
new!

Maybe you could try new tubes for V-5 and V-6, although the presence
of sound suggests that they are working.

I'm getting puzzled. Any other ideas, fellow AKers?

The cap marked 400v should be .1mfd

And I'm gonna ask this one more time. The height control pot. What is it's resistance supposed to be. This pot is checking in very oddly with me

Is there any chance I put an electrolytic in wrong, or that one is not functioning. And that this is causing ac to scramble the picture or something like this. I tried setting my voltmeter to ac on the dc line and it gave me alot of ac.

The cap marked 400v should be .1mfd

And I'm gonna ask this one more time. The height control pot. What is it's resistance supposed to be. This pot is checking in very oddly with me

I read 2.5 Megohms, that is 2 500 000 ohms and it does feed the plate of
V-14B with DC so it should be in good condition for proper vertical sweep.
However, the problem of the video signal not reaching the screen is
probably unrelated to this.

That pot has nearly 6 megs on it.

Some one had said before that the heater on the crt could be shorted somehow causing horizontal hum bars. What would these look like.

And its very strange. The tv shows snow on a static channel. If i looked at the tv in someones living room I'd say it was snow. But you tune it to a channel and it starts having bars and stuff again.
/
Tuning the horizontal control at the front of the tv makes these bars go ___/ the other way they go straight -------

Could the screen also be scrolling vertically at a high rate?

ANd I noticed that the audio output tube and the vert output tube get noticibly hotter than the rest.
If this overheating were not due to the voltages on the tubes, could it be some sort of oscillation that I can't see or hear

That pot has nearly 6 megs on it.

Some one had said before that the heater on the crt could be shorted somehow causing horizontal hum bars. What would these look like.

And its very strange. The tv shows snow on a static channel. If i looked at the tv in someones living room I'd say it was snow. But you tune it to a channel and it starts having bars and stuff again.
/
Tuning the horizontal control at the front of the tv makes these bars go ___/ the other way they go straight -------

Could the screen also be scrolling vertically at a high rate?

ANd I noticed that the audio output tube and the vert output tube get noticibly hotter than the rest.
If this overheating were not due to the voltages on the tubes, could it be some sort of oscillation that I can't see or hear

6 Megohms is definitely out of spec. That pot will have to be replaced.

What you're getting on the screen when you tune properly is likely
to be the correct video signal, with inadequate vertical sweep. The
effect of the horizontal hold control does appear to be normal.

So the area that needs attention is moving again to V-14 and V-15.
In addition to the height control, you have two more pots in that area
(R-422, linearity control, 800 Kohms and R-416, V. hold, 1.5 Mohms).
Every part in this area, including that capacitors, must be in good
condition so that the oscillator will free run at the approximately correct
frequency and will synchronize with received signal.

Since you don't have a 'scope, here's a trick that might help you
troubleshoot the Vertical sweep circuitry. If you can dig a cassette
recorder equipped with a loop designed for recording phone calls, and
get the machine to work in the 'tape monitor' mode (feeding the
signal being recorded to the earphone), you might first determine
that you can pick 60-Hz hum from single wire carrying AC. Then,
bring the loop close to the vertical ouptut tube and associated
circuitry. The waveform here is not a sine-wave but some kind
of sawtooth wave, but it should have the same fundamental frequency
of 60 Hz. If you hear something higher-pitched, you know something
is wrong.

The V. output and audio output tubes do dissipate a lot of power, so
the heating you are observing is probably normal.

As for hum bars, you would see two dark horizontal stripes on the screen
separated by an approximately equal height grey stripe. But since the
heater string is grounded at the CRT end, and you already measured the
cathode voltage to be correct at about 113 V DC, I don't think you need
to worry about this. Good luck.

That bumble bee cap must have been a replacement or something.(Its the only one in the whole set) It says it is rated at 60000pf If I did it right. (From the point with solder,Blue, black, orange, black, brown) This would be .06mfd.
Which makes me ask again. Is the cap just above v-15(12b4a). Rated at .0547(or is that unheard of) or .0047 as previously stated.



That bumble bee cap is just above v-15. Was .0547 the right value to replace it with?

And I will work on the rest of the things in this area. ALso that pot.

If you mean C-404, I read 0.0047 microfarad. This feedback loop made of C-404, R-425, R-419 and C-407 is quite critical for the vertical ouput circuit operation.
Good night.

Well then maybe my .0547 cap is screwing things up a little.:D
This could well be the problem to. The BB cap was way off value. And I think was also leaky.


For just testing. Would two .01mfd caps in series work as the .0047 just to see if it helps.

I have two .01's on hand.

Well then maybe my .0547 cap is screwing things up a little.:D
This could well be the problem to. The BB cap was way off value. And I think was also leaky.


For just testing. Would two .01mfd caps in series work as the .0047 just to see if it helps.

I have two .01's on hand.

Go ahead, that should be much closer than what you currently have.

So
I HAVE PICTURE, I HAVE PICTURE!!

Yes I'm not lieing. My .01 .01 series cap did the trick.
But as for the picture being perfect I wouldn't say it is exactly perfect.
Seems like its not vivid enough. Sharp enough. Contrast or something..
I'll play with it some more.

Also the tubes. They get hot right?(normally) Because always after a minute or two I smell the burning hot smell from the heating tubes. And I just wanna be told that's normal. (They're not glowing red)

:D It finally works

and I couldn't of done it without AK
Thanks guys

Wow! I'm so happy to read that. Hope you caught the bug! If you can get
that camera again, be sure to show us some pictures. Good luck, keep it going!

No it's mine and only mine to look at !

hahaha just kidding. I'll have pictures soon. I just wanna spend some time fine tuning it.
I'm very glad it works and would definatley do this again. And probably will.

And I still think that the image on the screen is above and beyond the top of the screen. This is a yoke adjustment if I am correct. But I have never done such a thing, and don't know where to start.(Do I just move it, loosen something, bring out the hammer :P )

also the image is sort of. Weak dare I say. It is showing up but doesn't stand out much. Or is this the quality of such a tv.

Pictures soon!

He he he I'm so happy

I'm having 0 success uploading pictures right now. But the picture seems very weak. And other channels wont even show picture. Any ideas as to why this might be?

It's very faint

I'm having 0 success uploading pictures right now. But the picture seems very weak. And other channels wont even show picture. Any ideas as to why this might be?

It's very faint

Do you have at least an old-fashioned rabbit ears antenna hooked
up? Also, the 4BQ7 RF amp on the tuner was weak; did you replace it?
Is the sound reasonably noise free? Typically, if you have adequate
sound, the signal is strong enough and a RF problem can be ruled out
as a cause of weak picture.

I'm having 0 success uploading pictures right now.

Maybe your pictures are too big, either file size, or dimensions. Problem is that the picture upload feature at AudioKarma doesn't report back what the problem was, it just doesn't do it. If I recall correctly, there is a note saying the max file size and max dimensions it will take.

Yes the sound is pretty good and clear. But it's not perfect.

And yes I have changed the tube.

As for antenna I have two wires hooked up. No rabbit ears. I haven't been able to find a pair.

And what about that yoke?


haha...I'm getting annoyed with the picture thing. I've tried shrinking the picture. I'll just have to do it later.

When reading about amps I always read that capacitors introduce phase shifts. My .0047 is "two" series capacitors. Could this possibly be changing the phase in the feedback loop causing some of this problem?

Unless the yoke was disturbed, it is probably correctly positioned. The trick is to
make sure that the waveforms feeding it are of the correct shape and amplitude.
Better wait until we can see some pictures.

As for your makeshift antenna, you can at least improve things by making it
resonant (on one channel). Find the center frequency of the channel you want
to receive (for instance for channel 7 it would be 177 MHz). Find the wavelength
in meters as 300/(F in MHz), in this case 1.69 meters. Divide by 2 to get the
half wavelength, that is 85 cm. This is the total length of your antenna (in fact
is should be a bit shorter, but if you take two 43 cm long pieces of wire and curve
the ends to fit the terminals, it should be fine).

Just attach the wires to the terminals and spread them horizontally. Be sure not
to get the wire ends in your eyes.

You might also use a VCR or DVD/VCR combo as a source, these usually output
on channel 3 or 4, but you will need a 75-to-300 ohm adapter (still fairly easy to
find as far as I know).

I was checking some tubes and I noticed that the 4bq7a is getting rather hot.
About as hot as the vert output or audio output tubes.

This can't be right? can it?

Heres another neat fact. The tv can only tune to one channel.

I should be able to get almost 4 but I only get channel 9. I suspect the tuner. BUt what part?

I also found an adapter. I hooked up my super nintendo. It did not even interfere with the signal. I am very confused

The tuner may need to be cleaned-a good electronic cleaner should do fine. (de-oxit seems to be a favorite, though I haven't used that brand) You basically give the connections inside the tuner a shower with it (with the set turned off) and then let it dry real well. Right after spraying I'll flip the tuner through the channels and spray a second time, to make sure you get everything covered.

Look for a control marked AGC, if you haven't already. Turned too far one way the picture/sound will go totally washed out; turn too far the other way and it will overload. You need to adjust it just so.

I wouldn't worry about that tube being too hot. It probably has a metal shield around it (or should) and that helps hold in some heat.

Well I went over the tuner sorta. I checked with my ohmeter to see that the switched were making contact. It checked in Ok. I also gave it a spray with some electric motor cleaner stuff I have. It didn't help any.

The AGC control you mentioned...I have no idea what it is. But the fine tuning does the same thing. Too far one way no picture. Set it just right and you get picture(For me it's on the one channel only)

I tried flipping through the channels. Turning the fine tunign slightly on each channel. I always end up at the same one.

Some of the channels will show static. And you hear the static. Other channels will give me a dark screen with no sound.
Others a solid grey screen.

Then on the one channel. I can get faint picture. With strong sound.

I have been trying to post my pictures But my internet is screwy or something. It just wont work.

Anyone have any thoughts on my series cap putting the feedback loop out of phase?

It seems that you need to check your AGC loop to make sure everything is as it should be there. If the AGC is not working then your picture quality--contrast, brightness, readability, etc--will vary greatly from channel to channel. In such condition your best channels for viewing will be of a critical signal strength--go below that and you may lose contrast--go above that strength and you lose brightness, or the picture may go black, or completely negative. Sync will also go out of whack, and horizontal and vertical hold will suffer.

It seems that you need to check your AGC loop to make sure everything is as it should be there. If the AGC is not working then your picture quality--contrast, brightness, readability, etc--will vary greatly from channel to channel. In such condition your best channels for viewing will be of a critical signal strength--go below that and you may lose contrast--go above that strength and you lose brightness, or the picture may go black, or completely negative. Sync will also go out of whack, and horizontal and vertical hold will suffer.

This sounds like it could very well be the case. But like I said before I have no Idea what the agc loop is. Could some one tell me where this is? what it is?

There is a "trimmer" (adjustable capacitor) at the back of the tv. For horizontal I think.

What does it do?

C-433

page 4 schematic.

P.S. If i Recap this tv, should I use orange dips or axial caps(Metalized Polyester Film "Tubular axials").

This sounds like it could very well be the case. But like I said before I have no Idea what the agc loop is. Could some one tell me where this is? what it is?

If you look at the control grids of each pix IF stage in a typical set you will see that the grid receives a negative bias which should grow stronger with stronger signal. Because it is the practice to use "remote cutoff" pentodes in the IF stages the increasing negative bias with stronger signal causes a cutback on total IF string gain, preventing overload. The AGC line feeds off the video detector as a rule, and supplies this negative bias. A shorted or leaky bypas capacitor from the line to ground may kill the AGC action altogether.

Sometimes it is simply that in fiddling around with a set that an actual AGC trimpot may have been disturbed, knocking the AGC out of adjustment, meaning that you could probably solve your problem with a simple tweak. These AGC level adjustments are usually found only on the higher-priced more elaborate sets, while most other more basic sets usually don't have such an adjustment.

Hello again,

Be sure to check your e-mail, I sent you some more documentation including a
discussion of the AGC circuits. Taking the time to read all this carefully should
be helpful. Good day.

Ahhhh thank you very much

The Tv shut itself off. Or screwed up wild it was turned on. I went to the back of it and noticed the fuse. That hooks up directly to line voltage was rather hot. Something is shorted out. Or a cap is open. I have no idea where. and it's making me mad. I wanna order capacitors but I don't have a large enough of an order to even do it. (And a man here sells the capacitors I need but at 4.50 a peice! for a .0047!)

I saw smoke come out of the tuner once also. I checked all the resistors in the area I saw smoke. They all seemed ok. But in this tuner are many "short" looking resistors(but I don't think they are resistors) They all check closed letting no current pass. What are these?

And as for the shorting problem(heating up fusible resisto) Would faulty caps cause this? Or something else.

And I don't have (Like i said before) a large enough order to get the caps I need. Unless I were to buy caps for my nordmende isabbella C console stereo. But I have no idea what it requires. Might anyone have a schematic for such a console or have done a similar one? Or will I have to rip my nice stereo apart.


And the Tv did not shut itself off. Luckily it unsoldered itself Where the b+ soldered to the diode I put it. And no real harm was done

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I'm sorry for hitting my keyboard
I just needed to do it.
listen to this and see why.

The antenna was connected to a tab. With three points. The middle point was grounded. From the middle 2 large value resistors went to the two outer points. The 2 outer points had the antenna hooked up to it. From these two outer points. The antenna signal was sent to the first tube via 2 capacitors then a transformer of sorts.

THIS FREAKING TAB WAS BENT. This bend it had. Made the signal from the antenna go directly to the capacitor then ground!!!!

I BENT IT AND THE PICTURE WAS 10x's better. And other channels showed up.

And I am rather annoyed by this simple fix. I was spending alot of time checking things and starring at the schematic to look for things to check. But thank God it's working. I just wish I found/thought of it sooner. I can't even beleive

It is ALWAYS something simple...the hard part is finding that simple thing.

I think the fusible resistor would get a little warm but I don't know what is normal.

Are you using justradios.com for your caps?

The bright side of it is that while you were doing all that troubleshooting, your mind
was absorbing more and more information about the principles and practice of TV
receiver design!

Don't worry too much about things being warm in tube type equipment. You said at
some point that you had added a resistor somewhere to drop the voltage. If the
DC supply voltages (+264 and +132) are reasonably close to the values shown on
the schematic, then the power supply is probably operating correctly. If those
voltages are too high, then a small resistor in series with each of the two diodes
would be the right thing, making sure that those resistors are correctly installed
to prevent any kind of shorting.

Bye for now.

Yes I am using the Justradios website for capacitors. They require 15$ minimum purchase as your probably know.

I will check the voltages of the power supply momentairly. I hope it is slightly higher. A resistor is a pretty easy fix!:yes:

And yes The learning is what it's all about really. Being 17 my brain just takes it all in. And by the time I'm older I'll be Pro.

Just like you guys:thmbsp:

P.S. If any one wants to see that nordmende I have for better reference. Or just veiwing purposes check this out http://www.audiokarma.org/forums/showthread.php?t=138633&highlight=isabella

Ummmmm.... I tested the voltages. From the + ends of both the 200mfd capacitors to ground. The results scared me.

From the first cap connected to ground (The 136+v) Was 250volts!
And the other cap was 475!!!!

How much extra radiation was I exposed to. Haha ha (I'm only half kidding there).

And Is this still just a fix with a resistor? If it is I'll be glad.

Maybe I tested it wrong. But I think not.

Ummmmm.... I tested the voltages. From the + ends of both the 200mfd capacitors to ground. The results scared me.

From the first cap connected to ground (The 136+v) Was 250volts!
And the other cap was 475!!!!

How much extra radiation was I exposed to. Haha ha (I'm only half kidding there).

And Is this still just a fix with a resistor? If it is I'll be glad.

Maybe I tested it wrong. But I think not.

Silicon diodes have a much lower voltage drop than a selenium diode. It is usually necessary to place a resistor in series with the diode to drop this excess voltage. Something between a 22 and 100 ohms should work. You'll just have to experiment with different values to see what resistor yields an output voltage close to what the schematic calls for. Just make sure you use at least a 10 watt resistor. Anything less will likely overheat and burn itself open.

Hello,

Be sure not to operate the TV until this has been fixed. I attempted to compute
the resistors required, but this is no simple problem. I will ask for some expert
advice from folks who have done it. Just look for the new thread.

So I need a resistor after the x-501 diode?
or Both?
I put a 25 ohm in originally but I guess it's not enough.

And I can post pictures now. Gimmi a while though

from before

I also have a large adjustable wire resistor. Goes up to about 200 ohms.
Should i give it a shot with it set to 100 ohms?

Be sure to drop the B+ voltage close to 264, otherwise you will fry something!
And I told you to leave it off in the meantime...
Good luck.

I did leave it off.

I know that 500 volts is near the maximum value of the tubes, (most likely) and you don't want anything like that. It actually made me sad when I found out I had been testing the Tv at 475 volts. I'm amazed it stayed alive for 30 seconds.

It wasn't until I put my 25 ohm and 150 ohm resistor in that I tried it.
The Voltage was actually too low. I've been paraleling resistors since then to try and get it up.
Voltage doesnt go anywhere near 400 anymore though. Which is a big releif


I only really have 2 problems now.
The screen is too wide
And the top looks a incy bit stretched. Other than that all seems well.

I did leave it off.

I know that 500 volts is near the maximum value of the tubes, (most likely) and you don't want anything like that. It actually made me sad when I found out I had been testing the Tv at 475 volts. I'm amazed it stayed alive for 30 seconds.

It wasn't until I put my 25 ohm and 150 ohm resistor in that I tried it.
The Voltage was actually too low. I've been paraleling resistors since then to try and get it up.
Voltage doesnt go anywhere near 400 anymore though. Which is a big releif


I only really have 2 problems now.
The screen is too wide
And the top looks a incy bit stretched. Other than that all seems well.


Once you get the power supply fixed (and take the time to do it right!),
you will learn to use the width (R-452) and height (R-421) controls
to adjust those things as needed. Good night.

Once you get the power supply fixed (and take the time to do it right!),
you will learn to use the width (R-452) and height (R-421) controls
to adjust those things as needed. Good night.

The height is Ok I think. It seems to be working better.

But the width is another story. I originally had a problem with this variable pot. So I switched it out and put a 5K as a temp. fix. This brought my HV back and I continued troubleshooting.

Now the 5 k pot in there was not enough to make the screen narrow enough. So I put resistors in there ( 3k 5k 10k) Untill it would get narrower.

But it never got narrower. I left the 10 k and the pot adjusted to full and the screen doesn't even looks like it got much narrower at all. The horizontal hold at the front of the TV does more to narrow it.(Or it just moves the picture over to the left and right)

More resistance or what?
Thanks
Rudy


So I ran the TV for about 20 minutes today. Played some Nintendo. Here's the verdict.

Mario was very very short at the bottom of the screen. And Mario was very very tall near the top of the screen. :D Fun game

And also the general picture was off the screen. Like I said before, the top of the screen is off the screen, by the time the bottom of the screen actually reaches the bottom.
The top is stretched, the bottom is compressed. I tried fiddling with ALL the controls. It cant be set properly.
Recapping the vertical or what needs to be done. Has some one had similar problems?
And also the fusible resistor is still getting rather hot. To hot to touch. The TV did hold up for the 20 minutes though.
Thanks
Rudy

heres some pictures
Everyone's favorite

70's show and a Tic Tac commercial

Just wondering. Is there any sort of symptom that causes picture to show but current is too high. Picture is poor. And adjustments don't work properly. I am just trying to get an idea of what might be going on.
Also some tubes are new some are old. Could this be causing this sort of problem/problems?
Thanks a bunch guys
Rudy

P.S. I am much more attached to this TV now since I decided to restore it. I want it to be at it's best. No matter what

Mario was very very short at the bottom of the screen. And Mario was very very tall near the top of the screen. :D Fun game

And also the general picture was off the screen. Like I said before, the top of the screen is off the screen, by the time the bottom of the screen actually reaches the bottom.
The top is stretched, the bottom is compressed. I tried fiddling with ALL the controls. It cant be set properly.
Recapping the vertical or what needs to be done. Has some one had similar problems?


Vertical circuits should benefit from a recap. Leaky caps will mess up the linearity. Also check resistors while you're in there.

Thank you Wa2ise
Good luck on your uhf vhf converter

Just wondering... Does anyone here actually put a piece of glass in front of the screen when they are servicing the components out of the box? I've noticed most picture tube data sheets say to do this.

Technically, yeah, I guess you should, but I never have. Not sure how you would do it on the bench. It seems to me that if the crt were to implode the face of the tube would be the least of the worries.

Great progress! Usually impossible to get the vertical running properly without all new caps in that circuit. The timing is critical and if it's off you really see it.

The glass sheilding Is not so much for the tube shattering but more the X-rays. But yea, I didn't use one either :P

Well caps is what I need then. Does any one by chance have a source that will sell only a couple capacitors?
If not I really don't know what I'll do. I'll have to either pay for "Italian" caps($$$)
Or order a bunch of capacitors I don't even need.
Or If some one knew where to get a schematic for a Nordmende Isabella model C Stereo console. I would order new caps for this. And my Tv and that would probably be a large enough of an order.

And I fully intend on enjoying this set. I have already played nintendo on it for at least a good half hour. And watched some 70's show. When the picture is more perfect I will be doing things like that ALL the time.

Should I use Metalized Polypropylene Film axial capacitors
or
"Orange dip" type capacitors, these are sort of radial.

The original ones in there are radial paper ones I think. With a black plastic shell.

You can see the ones I need help choosing here http://www.justradios.com/capacitors.html

Any input would be appreciated, thanks
Rudy

That set shouldn't be too fussy about capacitors. Just use Orange Drops or something of the sort--doesn't necessarily have to be polyprop. After all consider what the set had to work with originally. Just get some nonpolarised conventional cylindrical or dipped radial caps, and stick 'em in and be done with it is what I'd do.

You will likely need to replace all the caps eventually. Your pictures show that the vertical size and linearity controls are still not adjusted properly. If the potentiometers used for these adjustments are in good shape, and the associated capacitors are replaced, and all other fixed resistors check out OK, then you should be able to twiddle the two adjustments to get a good linearity. Bear in mind that both controls affect both size of sweep and linearity of sweep. IIRC the "size" control when decreased will shrink the bottom of the picture, and the "linearity" control will affect the top of the picture. But both controls interact, and you need to go back and forth between the two in order to get a good circle shape on the screen from a std test pattern.

I think I will go with the orange caps, Thanks.

As of right now the height control makes the screen get bigger or smaller.

And linearty makes the bottom of the screen cut off, and the top stretches out.

So I think a recap should help.

And a std test pattern, what is this exactly?

Hello again,

Replacing 'all the caps' is almost true, however, the small value caps that are
mostly inside the tuner and around the IF chain (V-3, V-4, V-5), typically
ceramic discs of silver-mica, are the most reliable. Priority should be given
to all the electrolytics, and all the big tubular coupling caps (mostly everything
that is .01 microfarad or larger). Check the notes regarding the types of
capacitors at bottom left of the schematic.

Since your most obvious problem at present is vertical non-linearity, the area
around V-14 and V-15 is the most obvious place to start the recapping, as
I trust you already understand.

By the way, did you notice the reference to 'brow' or 'side' (for instance different
values of C-200 at left of V-3)? In case you're wondering, this refers to the
position of the controls in various models using this chassis. In your case,
'brow' is the right keyword. Bye for now.

And a std test pattern, what is this exactly?

You've probably seen an old test pattern that shows a large circle with odd patterns inside and out, often with and Indian Head in the middle or a station identification. There are DVD's available with these on them. You don't really have to get that fancy-you just need some stationary pattern that you can use to judge linearity with. You may find one of the screens on your video games to work well. A big circle is good because you can easily tell if the picture is stretched.

Thank you all.
And I am doing as Electroking said. I am Only replacing the caps which are not ceramic disk or mica. And I have not used the schematic as reference to what I need. I am actually looking at the capacitors to read what they are. I want no mistakes.

And using the video game for a test screen is a great idea! There are actually some really good screens for doing it, thanks.

I'm ordering the capacitors now. And when they come in, and I put them in. I will be back to post pictures and tell of the great news.
Till then, Cheers
Rudy