http://i.imgur.com/J2YsicB.jpg

http://i.imgur.com/tqscm59.jpg

http://i.imgur.com/k4g1NP6.jpg


I almost didn't bring this home. I debated, then I wiped off the dust to get a better look at it. Apart from being dirty, the cabinet appears to be in excellent condition. I think the top is scratch free, which would be amazing! Also it's made from real wood, no chipboard here.

So I dragged the heavy sonofabitch home and made room for it.

I haven't gotten too far into it yet, apart from a quick cleaning, taking a few quick pics, and a powering on test. I'm thinking this could be a winter project for me, if all goes well financially. I'd like to get an idea when this set was made and what issues they commonly have/how reliable they are. This one briefly powers on before the circuit breaker in it trips.

The pictures aren't showing up :(

Guess I am not the ONLY one...who noticed that....

Changed links to imgur. try refreshing...

I tried uploading them here and linking in the post instead of having them as attachments at the bottom. Well it worked for me anyway...

SO...you have a D-12 chassis. I have one too. About 1968-69'ish.

Think it has about 8 or 9 tubes..INCLUDING a shunt reg and HV rect tube.H-out, damper and V-out.osc all tubes too. As is the video out and color amp.

IF, and audio are FULLY SS. Uses one large-TO-66 transistor for a_out, front of chassis, left side.

GREAT catch...I waited WELL over 30 YEARS...to get the one I have now !!

Get us some "nudies" of the chassis...if you can do so.

WE ALL enjoy "chassis porn" here !!

Will do tomorrow, and some better pics. Took these very quickly before wrestling the beast inside.

Any idea what might be causing the internal circuit breaker to trip?

D12 was a good chassis.
Usually tripping breaker is diode in bridge shorted.
If one is bad change all four.
If there is no loud hum then it may be just a weak breaker.
If it breaks after 2 or 3 mn look tward hoz out / hv area.
All of us looking forwards to working on it with you.

73 Zeno:smoke:

Almost the same type of design that my old Zenith solid state 1971 I had ( The cabinet )

D12 was a good chassis.
Usually tripping breaker is diode in bridge shorted.
If one is bad change all four.
If there is no loud hum then it may be just a weak breaker.
If it breaks after 2 or 3 mn look tward hoz out / hv area.
All of us looking forwards to working on it with you.

73 Zeno:smoke:

Ah, there is a loud hum for the split second that it operates.

I'm not familiar with changing out diodes, apart from knowing that they go in one way and their basic function is to limit current to flowing only one way. Is there a specific rating scale for them like resistors or capacitors? Can I substitute diodes from one of the various TV chassis boards I have lying around?

Put in ecg 125 diodes and you will be FINE. I PROMISE...(in the power supply anyway)

ECG125 is is 1000 V 2.5 amp. will sub most rectifiers BUT
not quite on a few solid state sets. So we used
ECG156 1000 V 3 amp. A little tougher & a little more $$
If thats what it is you could get 10 packs and have spares.
Common problem, we ordered them by the 100.
Next step is see if thats it or something else is dead shorted like
a big filter can.

73 Zeno:smoke:

Cheaper to buy 1N5408 3A, 1000V diodes - 39 cents for one. They are overkill - you could also use 1N5406 or 1N5407...

NTE and ECG parts were just remarked parts - the generic 1N's are usually cheaper.

ECG125 is is 1000 V 2.5 amp. will sub most rectifiers BUT
not quite on a few solid state sets. So we used
ECG156 1000 V 3 amp. A little tougher & a little more $$
If thats what it is you could get 10 packs and have spares.
Common problem, we ordered them by the 100.
Next step is see if thats it or something else is dead shorted like
a big filter can.

73 Zeno:smoke:

Since I never want to replace the diodes again, I'll go with the biggest meatiest ones that I can put in there.

BTW: More pics:

http://i.imgur.com/F9jBA8w.jpg

I swear the cabinet design of this TV screams "GRANDMA'S TV!" Now my Grandma never owned a set like this, to my knowledge, but had things gone differently this would have not looked at all out of place in her house or apartment. And seeing as she had a good bit of thrifty Scot in her, if this TV was cheaper then a comparable RCA or Zenith at the time, yeah she would have bought it.


http://i.imgur.com/qMtJe0r.jpg

I cleaned up the top with a good bit of furniture polish. The top has some light scratches and other small imperfections, but considering it's 45+ years old and looks like original finish, it's in excellent shape! :thmbsp: I doubt anything was directly set on top of this TV. I imagine the person who owned it, I keep thinking it was a grandmother, had various doilies and coasters on it, on top of which sat various knickknacks.

And she would have beat her grandkid's asses if they set anything on top of the bare finish, because she paid good money for that TV, dammit!

Well, before I set anything on top of it I'll put a towel over the top to protect the finish.


Chassis shots:
http://i.imgur.com/t4GbZVy.jpg
http://i.imgur.com/aXiPaxV.jpg

These were taken after I spent time and a lot of Q-tips removing a good bit of the dust inside.

And I found out the flyback can be accessed by raising the door on the cage:
http://i.imgur.com/0Sjx7uP.jpg

And it looks in damn good shape!

Great catch! I stuck it out with similar set recently until I fixed all the issues with it for another VK member. Looking forward to the play by play.

Sylvania color sets have quite a fan club at VK!

Sylvania color sets have quite a fan club at VK!

I can see why. this chassis looks like it has removable transistors. that and the boards are modular, making tracking down issues easier.

Also good to know that the folks here have experience with sylvanias.

A D12 Sylvania with a solid wood cabinet, very nice. I recall Ron, a.k.a. sampson159 saying that the D12 was introduced at the time Sylvania gave notice to the industry that they would make the best color TV.

I love my '79 with the E48-2 chassis. My only gripe about it is that the cabinet seems cheap.

Well I think I have a clue as to why the TV won't power up. I pulled the chassis to get a better look and...

http://i.imgur.com/a0VduVy.jpg
This ceramic cup wasn't attached to what I assume is the rectifier tube.

The cup is a very loose fit, so I examined it closely to try and find out why:
http://i.imgur.com/D9ImNAh.jpg

It's hard to tell from the pic, but the metal connector inside the cup is discolored, my guess is from electricity arcing. The metal tip of the rectifier tube is very dark.

So I wonder if that tube is still good? perhaps bending the contacts on the connector for a tighter fit might do the trick?

Edit: Nope. Same deal. Works for a second before the breaker trips.

Where are those diodes located? Perhaps I can pull them out and test.

this was the set that started sylvanias drive to the top.very,very good sets and a preamble of things to come.the next was the famous d16 series.same tuner as yours with a really fine crt.then came the best of them all,the d16 slide control.absolutely the best hybrid set right beside the zeniths of the era.excellent crt,simple designed chassis and nice cabinetry.they were also priced about 100.00 less than the zeniths and rca sets.sadly,they are gone now.in the shop days,the margin was 5 sylvanias to every 1 other set.in the southend of colunbus,we had the largest sylvania dealer in the country.

Nice set. I have one with the same chassis but the cabinet is trashed. The tube in your pictures is not the hv rectifier, It is a 6bk4 shunt regulator. The plate socket in your set will have to be replaced. The wire and cap are cooked and it will arc over if you use it. Also you will have to plan a play date with a soldering iron. re solder all the tube sockets and bad connections on the boards. Replace the power filters and breaker if replacing the diodes does not work.

I will pull the manual tomorrow & see where diodes are.
The plate cap you can pull off any set with a 6BK4.
There are many of them.

73 Zeno:smoke:

I will pull the manual tomorrow & see where diodes are.
The plate cap you can pull off any set with a 6BK4.
There are many of them.

73 Zeno:smoke:

Cool.

And there may be many plate caps where you are. Me? Not so much. So for now I've cleaned it up with sandpaper best I can and bent the contacts to make a tighter fit. Hoping that will do for now.

Cool.

And there may be many plate caps where you are. Me? Not so much. So for now I've cleaned it up with sandpaper best I can and bent the contacts to make a tighter fit. Hoping that will do for now.

That should be OK for now. What I meant was it was used in a lot of TV's
& you can get one off a junker.

4 diodes are under chassis under the power transformer. Test them first.
If any read shorted clip off one end & test again to be sure.

73 Zeno:smoke:

Right under the transformer? Okay. Maybe after dinner I'll see about pulling the chassis out.

Okay here's a shot of under the transformer. (linked for big)
http://i.imgur.com/TYAlSkF.jpg

I found 3 diodes, and something that looks like it popped, possibly the 4th diode? (look for the question mark near the bottom center of the image)

If it's the 4th diode, far as I know diodes don't just pop like that, so could something upstream pop it?

Okay here's a shot of under the transformer. (linked for big)
http://i.imgur.com/TYAlSkF.jpg

I found 3 diodes, and something that looks like it popped, possibly the 4th diode? (look for the question mark near the bottom center of the image)

If it's the 4th diode, far as I know diodes don't just pop like that, so could something upstream pop it?

4th isn't a diode, but your degaussing thermistor lost it's nickle. Dust out things and take another photo if possible - there should be a 4th diode if they are in a bridge.

Degaussing nickel should be an FR191 or a FR291 - and don't buy from the ripoff on ebay. Check Moyers or Talon

Okay, thermistor shouldn't be a big deal, I probably still have one or two from a junked TV chassis that'll work.

Cleaned out some of the dust and got a better pic. I think I found the 4 diodes:
http://i.imgur.com/evv5Qbq.jpg

Now... best way to test these I figure is to clip a lead and put my multimeter on them and see if I get continuity only one way. Best way to do that is to completely pull out the chassis. There's one wire stopping me from doing this, and indeed stops me from completely removing any TV chassis I intend to fix:

The flyback wire.

Before you suggest the screwdriver method of making sure it's discharged, let me give a big NOPE to that! There's got to be a better way to remove it, right?

Okay, thermistor shouldn't be a big deal, I probably still have one or two from a junked TV chassis that'll work.

Cleaned out some of the dust and got a better pic. I think I found the 4 diodes:
http://i.imgur.com/evv5Qbq.jpg

Now... best way to test these I figure is to clip a lead and put my multimeter on them and see if I get continuity only one way. Best way to do that is to completely pull out the chassis. There's one wire stopping me from doing this, and indeed stops me from completely removing any TV chassis I intend to fix:

The flyback wire.

Before you suggest the screwdriver method of making sure it's discharged, let me give a big NOPE to that! There's got to be a better way to remove it, right?

Two things - the rectifier diodes will check as a regular diode, with front to back resistance one way and open the other, or use a diode test function on your DMM, or just replace them outright with heftier ones - we used 1N5407s because they were cheap and good insurance that you wouldn't have a call back or have to pull the chassis again.

Second - to discharge the anode lead on the CRT - I use a grounded (chassis connected) clip lead attached to a long bladed screwdriver to discharge the CRT, then let it set for a few minutes and repeat. Then I grasp the 2nd anode rubber cup where the wire enters the cup and twist slightly, with some force to one side to dislodge the legs of the anode connector.

Remember -the CRT is what is charged (its a big capacitor with plates of aquadag and a dielectric of glass), and will obtain a "surface charge" just sitting, so always discharge the anode button to the aquadag before doing anything around the CRT.

Second - to discharge the anode lead on the CRT - I use a grounded (chassis connected) clip lead attached to a long bladed screwdriver to discharge the CRT, then let it set for a few minutes and repeat. Then I grasp the 2nd anode rubber cup where the wire enters the cup and twist slightly, with some force to one side to dislodge the legs of the anode connector.

Remember -the CRT is what is charged (its a big capacitor with plates of aquadag and a dielectric of glass), and will obtain a "surface charge" just sitting, so always discharge the anode button to the aquadag before doing anything around the CRT.


Hoooo... nope nope nope nope nope! If I have to I'll leave the wire connected and work around it instead.

Hoooo... nope nope nope nope nope! If I have to I'll leave the wire connected and work around it instead.

I take it you've been shocked before, or have a pacemaker?

Do what you are comfortable with - Safety first.

The discharge procedure is pretty much standard - RCA wanted a 56K resistor in series with the ground, but later made a discharge tool - basically a HV probe with a pushbutton discharge button.

As long as the 2nd anode lead is connected, the cathode of the HV rectifier has juice on it, and still poses a danger if you are working near it.

I've been bit a dozen times and never had any ill effects - just an adrenaline kick and a few choice words. :grumpy:

Actually no I've never been shocked before. Been repairing CRT TV's for 10+ years, never been shocked once.

Because I knew early on that CRT's pack a nasty punch, so I just leave the wire connected and work with the chassis inside the set... or desolder the flyback from the board. Since that's not an option I'll work around it. Pain in the ass, but it won't leave me lying on the floor twitching...

Okay very first diode I clipped reads as a dead short in both directions. I think I've found the problem. I'll have to put this on hold until I can spare the cash to order some diodes. Unless I can substitute some from a junked TV chassis. Problem is while I know how to read resistors and capacitors, or can look them up easily enough, I have no idea how diodes are rated and what ratings matter...

Like I know you can replace a capacitor with one rated for a higher voltage so long as the capacitance is the same. You can replace resistors with higher wattage ones so long as the resistance is the same. What about diodes?

C'mon...I have been knocked on the ground a FEW times...ALL by the HV of a set. I have been ALSO hit by a boost converter--(around 400 Vdc), H-out cap and focus voltages. It is NOT that bad really. NONE of those...have discouraged me from loving to work on this stuff...old and NEW.

Just an unfortunate aspect of this hobby--or profession...

Actually no I've never been shocked before. Been repairing CRT TV's for 10+ years, never been shocked once.

Because I knew early on that CRT's pack a nasty punch, so I just leave the wire connected and work with the chassis inside the set... or desolder the flyback from the board. Since that's not an option I'll work around it. Pain in the ass, but it won't leave me lying on the floor twitching...

Okay very first diode I clipped reads as a dead short in both directions. I think I've found the problem. I'll have to put this on hold until I can spare the cash to order some diodes. Unless I can substitute some from a junked TV chassis. Problem is while I know how to read resistors and capacitors, or can look them up easily enough, I have no idea how diodes are rated and what ratings matter...

Like I know you can replace a capacitor with one rated for a higher voltage so long as the capacitance is the same. You can replace resistors with higher wattage ones so long as the resistance is the same. What about diodes?

PM me your address and I'll send you 4 diodes - beefier than the ones you have in the set now.

With rectifier diodes, you can go up in current and voltage handling capability. The diodes in your set are probably 400V, 1A diodes, maybe 600V, 1.5A diodes. As long as the voltage rating of the diode (PIV, or PRV) is higher, you can use the diode. Same goes for the max current rating or IF (I-forward). Higher is better, but please make sure there is a fuse around if on the secondary of a transformer - transformers are the one thing we don't get to upgrade easily, and they can be taken out by shorted rectifiers if not fused.

C'mon...I have been knocked on the ground a FEW times...ALL by the HV of a set. I have been ALSO hit by a boost converter--(around 400 Vdc), H-out cap and focus voltages. It is NOT that bad really. NONE of those...have discouraged me from loving to work on this stuff...old and NEW.

Just an unfortunate aspect of this hobby--or profession...

Unfortunate, yes. But each of us has our limits, and with safety as the primary concern, I fault no one for extra caution.

I've seen guys get shocked, shake it off, and drop dead within hours - their hearts damaged by enzymes that elevate after a shock. Likewise, I've seen first hand the nerve damage done by boost voltages - it was my Dad, and he had nerve damage that lasted for years, with white tissue scarring all along his arm where the voltage traveled along. He couldn't pick up a coffee cup with that hand for 6 months, and the shooting pain (actually nerves repairing connections) went on for months. The scarring took years to disappear.

So yes, let's be careful and mindful of safety at all times. And please fault no one that goes the extra mile to be safe. I'd rather read of their fortunes than misfortunes....

Unfortunate, yes. But each of us has our limits, and with safety as the primary concern, I fault no one for extra caution.

I've seen guys get shocked, shake it off, and drop dead within hours - their hearts damaged by enzymes that elevate after a shock. Likewise, I've seen first hand the nerve damage done by boost voltages - it was my Dad, and he had nerve damage that lasted for years, with white tissue scarring all along his arm where the voltage traveled along. He couldn't pick up a coffee cup with that hand for 6 months, and the shooting pain (actually nerves repairing connections) went on for months. The scarring took years to disappear.

So yes, let's be careful and mindful of safety at all times. And please fault no one that goes the extra mile to be safe. I'd rather read of their fortunes than misfortunes....

Exactly. Taking a full 15 KV of HV is no badge of honor. Had rca2000 been hit while his heart was at a certain spot in its beating cycle, he'd have gone into afib and likely died.

I like to blow things up and set things on fire. Never had a fire get out of control, and never damaged anything I didn't intend to with an explosion.

Same principle applies to doing my own electrical work. Again, never been shocked, never caused the house to burn down. Actually saved the house from burning down once because I kept getting a faint whiff of smoke and traced it to aluminum wiring for a light fixture twisted onto copper wiring. The connection had corroded and was close to starting a fire. So I rewired the fixture using proper copper wiring.

It all comes down to giving dangerous things a healthy respect and not touching them unless I know what I am doing. And with discharging a CRT, I'd be too nervous to keep a steady hand and would jump at the slightest pop, possibly causing the screwdriver to go somewhere it shouldn't.

So I'll work around the problem. Luckily these diodes are on the opposite side of the chassis, so I have room to get to them.

Well, BE SAFE guys !!,, don't be stupid when you repair your TVs.. No need to know if the current is okay by touching something around the HV cage or else with your hands ouff !!..The warnings are there to be respected when the TV set have need to be repaired...Sorry my English not good .

I assume you want to pull the chassis out ? Usually
you can flip it on edge & run it. Just dont put strain
on the wires. Can usually put a box behind the set
to rest it on. Alternitive is flip the whole set on its side
HV area down & you can run it & do tests. Sets with bottom
plates like Zeniths are almost always done that way.
Just remember the purity will be way off, thats normal.

One other important thing. Until you change the thermistor
JUMP IT OUT or the VDR will burn. They stink too !!!

On HV shocks be as careful as you wish. If you are
healthy it should not harm you but.......
I have got nailed many times by HV. Worse it did
was give me A-fibs for maybe 20 sec. a few times.
In fact if you already have A-fibs it may cure them if
the timing is right !
When they fix them they put a ground on your back
then on your chest. The machine has a sync curcuit &
at the right point SNAP ! And you are back to normal
rhythm often. You are asleep during it. I had it done
3 times.

73 Zeno:smoke:

It all comes down to giving dangerous things a healthy respect and not touching them unless I know what I am doing. And with discharging a CRT, I'd be too nervous to keep a steady hand and would jump at the slightest pop, possibly causing the screwdriver to go somewhere it shouldn't.
I use a HV probe for that. Nothing to it, just watch the needle climb and quickly drop.

One other important thing. Until you change the thermistor
JUMP IT OUT or the VDR will burn. They stink too !!!



Good to know. I'm assuming I can throw in a thermistor from any BPC set of a similar size, right? If so, then I have a replacement on hand already.

Good to know. I'm assuming I can throw in a thermistor from any BPC set of a similar size, right? If so, then I have a replacement on hand already.

MAYBE so find an exact replacement. Its 125 ohms cold.
syl p# was 38-17071-2 It will cross to a workman ?FR922?
For now just short it out & repair the set. The degauss just
wont work.

73 Zeno:smoke:

Are you sure about shorting the leads together? I ask because the last thermistor I replaced, shorting the leads would have fried the degauss circuit. This was on a much newer RCA CTC... 187 I believe, but I figure a degauss circuit works pretty much the same?

If shorting the leads together is safe, I'll do that.

When the thermistor is in the set, it starts out at ~ 120 ohms, and DROPs in resistance as it warms up, to about 2 ohms or so hot. Shorting it out puts no voltage in the degaussing coils, so your degaussing is disabled until it is replaced.

From the RCA patent:

The thermistor is a device which when cool has a relatively high resistance but when hot has a relatively low resistance. The degaussing magnet coils are energized by the voltage drop across the thermistor in a circuit which includes a varistor (voltage dependent resistor). The varistor is a device which has a relatively low resistance when a high voltage is impressed across it and a relatively high resistance when the impressed voltage is low. It will be observed that the resistive properties of the thermistor and the varistor are of a reciprocal nature.

The energization of the degaussing coils is as follows, assuming that the thermistor is cold, i.e. at room temperature. immediately upon closure of the power switch the current flow through the thermistor to the power supply produces a relatively large voltage drop across the thermistor. At this time the resistance of the varistor is low so that alternating current flows through the degaussing coils at considerable amplitude. As a consequence, a relatively strong alternating field is established in the screen region of the picture tube. As the thermistor warms in response to current flow it's resistance decreases thereby decreasing the voltage drop across it. As a result of the decreased voltage the resistance of the varistor increases thereby decreasing the current flow through the degaussing magnet coils. As a consequence, the strength of the alternating field produced in the picture tube decreases. The thermistor ultimately heats sufficiently that its resistance and the voltage drop across it are very small so that the resultant voltage applied to the varistor is so small that the current through it and the degaussing coils is so small as to be effectively zero.

For BPC sets, the thermistor is about 16-25 ohms cold, too low to energize the coils in your set effectively. Get an FR191, FR291, or FR922 thermistor for your set. All three have relevant RCA part numbers with the last digits of the RCA part number matching the 191, 291, and 922......betcha a lot of folks wondered how they got numbered.....now you know:

107191 = FR191
107291 = FR291
RCA drawing number 942922 and all suffixes = FR922, or FR291, both are heavy duty 120 ohm thermistors.....

Cheers,

Right. I'll just short the leads together until i can get a suitable thermistor.

Right. I'll just short the leads together until i can get a suitable thermistor.

Allied Electronics and others have GE's CL-90 that is 120 ohms cold, rated for 2 amps. $2 each

Right. I'll pick up a thermistor once I get the set working. If I'm lucky all it needs is those diodes to bring it back to life.

You should get an HV probe to use it to discharge the CRT, and confirm HV reg is adjusted properly once you get it going. If you use an HV probe, the CRT second anode should not 'recover' any voltage, and you get to see that it has discharged to a safe voltage. Just clip the ground lead of the probe to the chassis, hold probe by user handle stick the tip on it's far end under the HV suction cup or to the plate at the base of the HV rect tube if more convenient, and watch the needle jump and fade back to zero.

Honestly, if you are wearing rubber soled shoes and not touching any metal that leads back to the chassis you could touch the HV lead with the set off and it would not be much worse than a static shock from shuffling your feet across the carpet and grabbing a door knob.....If you change that situation to holding the handle of a large insulated screw driver with the metal tip touching the HV you should feel nothing since there is far too much insulation for current to flow thru you even if the ground jumper were to fall off.

If the CRT has not lit for you there probably is no or very little HV.

I can understand being a bit squeamish after a jolt, I've had enough of them to know (99% were reconnecting the lead after the screw driver discharge and bounce back, which I learned to avoid by leaving the CRT's HV connector grounded until reconnect), but your irrational fear of the unknown is just being a big freaking chicken....Unless you have a bad heart condition or the like.

If you get shocked from the yoke somehow (I say somehow cause the only time it happened to me I could not figure out how) with the set on, you will then not worry about small HV jolts.....I've never had my reflexes hard triggered by the HV (sure I'd consciously pull back in a controlled way), but the yoke....without trying everything in my way was smashed out of it including some wires. Yoke voltages and 120VAC are the two things I work with that I'm thoughtfully cautious around.....Now that I have an HV meter I just discharge and stop worrying.

If you are truly dedicated to/focused on working on something (as any experienced auto mechanic will tell you) you will not notice or care as much about small pain. When I was starting out soldering I often would cause my self small burns and not notice until minutes or hours later. I've given my hands small cuts while working on some things and not noticed until long after.

MAN UP!

Honestly, if you are wearing rubber soled shoes and not touching any metal that leads back to the chassis you could touch the HV lead with the set off and it would not be much worse than a static shock from shuffling your feet across the carpet and grabbing a door knob.....
Sounds like what happened to me after I aired a bad CRT in a console that had been running shortly before. Back then I had no HV probe. I got a small bite when reaching for a piece of glass dangling from the remains of the evac stem.

Anyway, no pain, no gain. :D

You should get an HV probe to use it to discharge the CRT, and confirm HV reg is adjusted properly once you get it going. If you use an HV probe, the CRT second anode should not 'recover' any voltage, and you get to see that it has discharged to a safe voltage. Just clip the ground lead of the probe to the chassis, hold probe by user handle stick the tip on it's far end under the HV suction cup or to the plate at the base of the HV rect tube if more convenient, and watch the needle jump and fade back to zero.



I might pick one up, when I can afford to do so. Right now I can't even afford a thermistor much less an HV probe.

And the rest of your post was unnecessary. You're talking to a guy who recently wrestled with the exhaust system on his truck for 12 hours before the damn parts would line up. I'm no stranger to working on vehicles, or the various injuries resulting from it. Any stripes that I needed to earn, buddy I earned them years ago and there's nothing cowardly about not wanting to risk 15 KV traveling through your body.

there's nothing cowardly about not wanting to risk 15 KV traveling through your body.

In my book there is, especially given the method your scarred of. The screw driver method was a safe and common technique among service techs for decades....I've even seen SS sets that have warnings not to use that method because the SS HV system was not built to take it. I've done the screw driver bit dozens upon dozens of times before and after I got an HV probe (surprisingly easy to miss-place for a 1' long stick). I've never been shocked doing it, even when the ground clip lead has slipped off the driver mid way through....Hell I've even used wood handled drivers once or twice. Only jolts I've taken are from anode recovery when reassembling (eventually realized that leaving the jug clipped to ground prevents even that), and once or twice forgetting to discharge the HV before removing the suction cup....That don't feel good, but I've gotten bit MUCH worse by 120VAC.

If you work on CRT TVs as a habit you WILL get bit by the HV or MEANER voltages/waveforms eventually, just a matter of time. And it's only spooky until it stops being an unknown experience.....Then it becomes more of a minor nuisance....Like dropping a heavy set on your foot or stubbing your toe (only the pain don't last nearly as long...5sec to 5 min tops), you cuss a bit and move on unphased.

Let's agree to disagree then.

Anyway I'm hoping I'll get lucky and the set stopped being used early on because the diodes shorted. I see Sylvania tubes in the chassis, suggesting they're original and the set might be a low hour set.

My theory is somebody's grandmother bought it 40+ years ago, and they paid good money for it so they weren't about to throw it out, so it probably became a table to set knickknakks on until it was tossed.

Thanks to a generous donation from Findem-Keepem, I received the diodes I needed. So now to replace them. Hmm... how to get at them without fully removing the chassis? That's a problem.

Fortunately I'm good at finding solutions to problems:
http://i.imgur.com/gqnU99t.jpg


So here's my, er, less then elegant repair:
http://i.imgur.com/0U1Ykn5.jpg

Not pretty but if it works that's all that matters.

So now to power it on, but first I need to do the following ritual, what I do every time before I plug in a TV that I've been working on. I connect it to my power strip with the kill switch ready, then I put my hands together and say the following:

"Please Lord, don't let this thing blow up!"

Here we go... the big moment. Shall I be joyous? or shall I be damned?

It's alive!..... barely.

http://i.imgur.com/Ndzwqwr.jpg

So the HV comes up after about a minute or so and I see what looks like a very faint, very out of focus image. I noticed the brightness knob was maxed out, suggesting the previous owner had this issue as well.

My guess is the HV is very weak. I'll need an HV meter to be sure though. Wish I also had a CRT tester so I could see if the tube is shot.

EDIT: connected a DTV box. Tuner seems to be working. knobs are scratchy, to be expected. No horizontal hold, though I think vertical is stable... hard to tell with such a dim, out of focus image.

So I was thinking... When I fixed that Motorola tube TV I had to clean the tube pins. So I just finished removing and cleaning each of the tubes in this TV... except the tube that that ceramic cup attaches to. I can't pull that one out.

Ran into a headscratcher looking for a tube that was labeled as being for HV regulation. diagram said it was locared where the flyback is... wait... what's that above the fly-- there it is!

So I pulled it out and saw that like the other tube, the connector on top was corroded. Might explain the faint blurry image. So I cleaned it up and put it back in. Let's see what happens.

Well, it helped slightly. Picture's a bit brighter. Still extremely blurry. Very low contrast.

The CRT on a Sylvania are not tough !... i had 2 Sylvanias , both had a weak CRT and one of the 2 was shot.. i had them 10 years ago. Good luck with yours.

If there is a HV regulation control, note position so it can be returned then, and then try adjusting it for more brightness. If the HV reg heater is glowing rather bright then it is probably not working right and dragging down the HV....unplugging the top cap is an option to deal with that.

The cabinet is French Provincial style. It was a popular style in the 60's....I have an example and have seen many sets in that style.

Could a weak video output tube also be causing the picture issue?

I had a look at it last night with the lights out, and far as I can tell, all the tubes glow, however the tube labeled as being for video output was glowing the weakest.

That tube appears to be original, or at least a very old Sylvania tube. I wonder if that can be used to provide a rough figure of the set's hours.

Some of the other tubes, including the one above the flyback are RCA branded.

Did you DeOxit those slide switches on the rear apron of the chassis?

BTW, there's usually a "one-way jaws" hold-down clamp preventing the HV regulator tube from being pulled out. To release it, you have to push down on both sides of the clamp while pulling the tube.

Oh, no, I should probably try that.

And the HV regulator tube didn't have any jaws holding it in place.

From the pix the focus itself seems to be good.
There is a focus coil. You can adjust it to see if
it focuses best in range. If it goes to either end &
focus getting better but not good may be a bad
focus rectifier.
Seems to have good width so if its HV related its
probably the 6BK4 or 3CU3. If you pull the 3CU3
grab it at the cap end, you may get bit near the socket.
Also the big plate cap for the 6BK4 has HV on it until
discharged.
If HV is OK brite prob. could be adjustments, video problem,
boost problem or CRT.

73 Zeno:smoke:

I just had the set on, lifted the flyback cage door and did not see a glow from the tube that it plugs into.

Also cleaned all the switches, no effect.

HV rectifiers often dont light. they just need a little heat
to emit. Usually a weak rectifier causes "blooming".
As you turn up the brightness the pix expands like zooming,
the brite drops & the focus gets worse. HV regulation can do it to but not
as bad. For now try this.
Turn up the R, G, & B screen ( G-2 ) controls one at a time then
return them to where they were. You should get a brite pix
from each one. The CRT is magnetized so the colors will be blotchy.

73 Zeno:smoke:


I just had the set on, lifted the flyback cage door and did not see a glow from the tube that it plugs into.

Also cleaned all the switches, no effect.

All three screen controls were turned fully clockwise. Whoever worked on this set before me must have tried this.

Setting them to about the halfway point produced no change in the image. Turning one fully up or down produced no change in the image. The screen controls do nothing noticeable.

Perhaps the B+ boost system is dead.....Connect a DC volt meter to the wiper of one of the screen pot with it set at min, and then turn the pot up. It should read something like 350V or more (need to find and check my D12 schematic) with the set on and warmed up, and rise as you turn the control up. If it does not rise the B+ boost is out....Could be from a shorted cap filtering that line, an open boost diode, or a few other things. B+ boost is likely around 1200V so it is likely unsafe to measure it with the set on (unless your meter goes well over 600V), but that voltage should bleed down quickly once the set is turned off.

Sounds like no boost.
IF you have a meter that is OK at 1000V......
one end of the control will have abt 200-250 VDC
the other 900VDC. The wiper will vary between the
two. Hopefully the 900V is missing or very low.
You can measure them at the top of PCB
at the pins.

73 Zeno:smoke:

On second thought I don't think my meter can handle that. Yeah, it's 600 volts max.

So perhaps i shoulld check the parts related to that line. Where do I start checking?

On second thought I don't think my meter can handle that. Yeah, it's 600 volts max.

So perhaps i shoulld check the parts related to that line. Where do I start checking?

As long as you measure the wiper (center) pin voltage at the pot and watch the meter as slowly turn the pot up from min you won't damage your meter....They can take some more volts on their input than their rated to measure.

Might take a stab at it tomorrow. To be sure, fully counter-clockwise should be the minimal setting?

Might take a stab at it tomorrow. To be sure, fully counter-clockwise should be the minimal setting?

Should be....Have not ever seen it the other way.

Bettin' on the boost diode.

A little tip FWIW: On sets lacking a removable service panel on the bottom, It's much easier to work under the chassis if you turn the whole cabinet up on end and slide the chassis back enuff for access. Common shop practice. They had carpeted service carts to set 'em up on.

Okay, so getting to the center pin on any of those screen pots isn't happening. I'd have to disconnect some wires that I'd much rather not touch since I don't know where they go, what they control, and might have trouble putting them back.

I have to assume there's a test point on the chassis to test for B+ right? I notice a lot of pins up front. If I set the screen pots to minimum and use a test point, could I test for B+ without frying my multimeter?

Also noticed that not only were the screen controls turned to max, so were the drive controls. Someone before me definitely had this issue. Hope the CRT is okay.

Boost rectifier is behind focus control. Probably a large brown one with
silver on one end & gold on other. Then it goes to the G2 controls
through a 100 K ohm resistor.

73 Zeno:smoke:

Hm, not sure what it's supposed to look like. Here maybe this will make it easier for us to find:

http://i.imgur.com/LhY12cV.jpg

That white shaft in the upper left corner is the focus control. Nothing's directly behind it, though there is something that vaguely looks like a fuse (top of the image, right of center) that's brown and silver on both ends. Is that my test point?

That thing half cut off at the top center of the pic is probably the boost diode, but unless it is weak/dead it probably will be too high a voltage for your meter....That is why I said to measure it through the screen pot.

If you can't clip directly to the screen pot wiper terminal, then pull the CRT socket, stick a wire about the thickness of the CRT pins into a pin that connects to a white wire with a color stripe and use that as the wiper pin test point for a screen/G2 pot of the color of the wire stripe. Measure voltage to ground with the pot at min, and turn up the pot if the voltage does not rise with the pot setting and get high enough, then the boost system is weak or dead.

Another option would be to measure the B+ boost with reference to the high power transformer derived B+.....Connect the meter negative to the positive of the first lytic fed by the diode bridge you replaced, and connect the positive to the B+ boost line. The boost voltage will be the voltage of the bridge WRT ground + the voltage you measure... The meter may still get more voltage than it can measure this way so the G2 wiper method is preferred.

Do you have a schematic? IIRC I have a Bietman's most often needed Color book with the schematic for the D12 chassis that I could probably scan or take photos of for you.

Okay, removed the CRT socket and used a suitable wire to connect to a white wire with a blue stripe. Grounded the negative lead to the chassis frame.

On power up, got around 30 volts. As the set warmed up, the voltage climbed 125... 200... 300? 400?! At around 500 volts I cut power. This is with the screen pots at minimum... I think if anything the B+ is too high.

And no, I don't have a schematic. I'm basically working on this thing blind and with little clue as to what a lot of these components do.

...Grounded the negative lead to the chassis frame.
What he was sayin' was connect the meter's negative lead to the B+.

The 'Boost' (or B boost) voltage is stacked or 'bootstrapped' on top of the regular B+ supply. Be careful though, since the whole meter will be riding at B+ potential.

I have a D-12 sams. 1045-2

'Sams shows ir as "X29" and it IS indeed on that terminl strip... so I wuould check the voltage there.

But if you are getting OVER 500 volts to the G2 on the tube. with the G2 controls at MIn.....it is NOT likely a problem....

Reversed the leads, same voltage readings, but negative this time. Lets say the B+ is good. What else would be causing this dim, blurry image.

I may take a video of it to show you guys exactly what it's doing. if it'll help let me know and I'll do it.

Okay I figured making a video wouldn't hurt, and might shed more light on what's wrong with this set.
http://www.youtube.com/watch?v=emRtksG5vgM&feature=youtu.be

You may *barely* be able to see the video flicker on the screen as I change channels. Interestingly the image brightens a lot as it's being shut off. There's a noise like static electricity discharging coming from the flyback area, tried to capture it on camera.

I thought all the tubes were glowing. Not so sure now. Maybe i was imagining it.

Interestingly the image brightens a lot as it's being shut off.

My Silvertone roundy did that when it's boost diode was open....I still suspect the boost/screen system. I'll try to get my schematic out tomorrow so I can check your measurements against what the set should be doing.

I'd like to know where that boost diode is so I can pull it and check it.

I'd like to know where that boost diode is so I can pull it and check it.

Pointed out in an earlier post, but circled in green here.

That thing half cut off at the top center of the pic is probably the boost diode,

Pointed out in an earlier post, but circled in green here.
To me, with those black stripes It looks more like a barberpole resistor. Hafta see more of it to tell for sure.

Here's a better shot of it:
http://i.imgur.com/jdIpl2D.jpg

I clipped a lead and tested it. If it's the boost diode, it tests open both ways.

A video would help. Do it on youtube so everyone can
see it EASILY.

After the video try this:
Put all the G-2 ( screen) and the 2 drive controls to mid
range. Measure the CRT voltages.
Usual wires are solid colors, white /w tracer, yellow w/ tracer.
three of each.
DO NOT DO THE FOCUS its the black wire set apart.
Dont bother with the filament, twisted pair of brown.
Post results.

73 Zeno:smoke:

I clipped a lead and tested it. If it's the boost diode, it tests open both ways.

As it will - it's a high voltage selenium rectifier, and the forward voltage drop is beyond what a DMM/Ohmmeter/Diode check function can provide.

Only two ways to check - with the set on, measure the Boost (~900-1100V - more than a DMM can handle) with a VTVM =OR= replace the rectifier and run the set.

At SOME point...you MUST check that CRT. As much as we hate to admit it...sometimes they DO die.....and sylvania tubes seem to die quicker than most.

Hopefully...it is NOT the tube--but you DO need to know. I have had sets before...with tubes SO waek on all three guns...they just would NOT hardly light....till "pounded on" with a rejuvinator...

At least THEN...you will know. ANd if it is NOT the CRT...I would look for a near total loss of video drive and such....assuming all voltages for the CRT screens and such are ok.

A video would help. Do it on youtube so everyone can
see it EASILY.

After the video try this:
Put all the G-2 ( screen) and the 2 drive controls to mid
range. Measure the CRT voltages.
Usual wires are solid colors, white /w tracer, yellow w/ tracer.
three of each.
DO NOT DO THE FOCUS its the black wire set apart.
Dont bother with the filament, twisted pair of brown.
Post results.

73 Zeno:smoke:

You mean like the one I posted in this thread yesterday?
http://www.youtube.com/watch?v=emRtksG5vgM&feature=youtu.be

Not sure what else to make a video of.

Okay I set the screen controls to about mid way and I've measured all the wires on the CRT socket except for the black wire, and the brown ones.

White wire/blue stripe Over 500 volts
White wire with red (brown?) stripe 800+ (cut power at 866 volts)
Yellow wire with red stripe: Starts off at 350 volts, drops to around 330 when the set warms up.
Green wire: Starts off at 360 volts, drops to 180
Yellow wire with blue stripe: Starts off at around 335, drops to around 325
Dark blue wire (violet?) starts of at 330, drops to 170
Third yellow wire with dark stripe (not sure of stripe color): starts of at 350, drops to around 330.

and rca2000 I would love to check the CRT. Do you have a tester I can borrow?

Where are you? Liklely you are WAYYYYY too far away from me. I have a GREAT CRT tester--the sencore CR-70. If it can;t help your tube....NOTHING will !!

BUT...I live in SW Ohio... Where do YOU live?

I will BET...SOMEONE in your area DOES have a tester you could use though...

Near Detroit...

OK...others here will have to help me...but...

That 800+ volts tells me your B boost IS working ok. With that lrvel of voltsge...you SHOULD have enough screen voltage..

HOWEVER.....some OTHER voltages seemed HIGH to me. If you are getting over 300 volts to the CATHODES of the tube...it will likely be in CUTOFF... that is where I need help...not sure which leads go to the cathodes. But IF your cathodes are biased too much positive...there will NOT be much emission.

On a SS set with combined Y-C at the tube--...one could "force on" the cathode of a particular gun and then see if the tube would flare to retrace of that color. If it DID...and the raster was pretty bright of that color...it would usually rule out the CRT---for a symptom of no/low brightness..

But on a DELTA gun tube on a TUBE set...not really sure HOW one could do this. Perhaps someone else knows...

There are several guys up that way. Captain Moody for one. He likely has a tester.

What would happen if I messed with the CRT bias control? There's also a control mounted to the flyback cage, several inches above HV ADJ control. What's that do?

The Bias control should increrase the brightness. that IS worth a try.

The controls above the HV adj. are for vertical and pin cuhsion and will NOT help you...

I STILL...thik you have a video drive problem...

I think there's a video drive problem as well.

I don't know what shape the CRT is in but I doubt it's screwed to the point where it can barely produce an image.

Adjusting the screen controls do nothing, but the voltage is there.
The brightness control has some effect.
EDIT: Strike that the tubes are all glowing, it's just hard to see.
And when shutting the set off, the image brightens as it shuts off.

I think what I might try next is replacing the tube or tubes that are most likely related to the issue. The 12HL7 is a good suspect as it's for "VIDEO OUTPUT" also it looks to be the oldest tube in the set. It is glowing but could it be weak or have another issue?

When you turned off the set it was brite white for
a sec so lets assume the CRT is OK
G-2 ( white w/ stripes ) are OK so boost OK
G-1 ( yellow ) are high BUT they only carry color info.
Cathodes ( solid colors) high, should be abt 140 VDC. This is the B&W
info. Cathode high= pix dark. Cathode low = brite.
Measure the 12HL7 voltages. Count pins CW from under, CCW from top.
Usually you can get it from the top. Bias is in color part but try anyhows also.

73 Zeno:smoke:

Okay, just measured the voltages for the 12HL7 tube. The gap in the tube socket is at the 12 o'clock position, so I took the measurements starting clockwise. Positive lead of multimeter connected to tube pin and negative to chassis frame:

Pin 1: 0 volts.
Pin 2: 355 volts on startup, dropping to 305 after warm up.
Pin 3: 355 volts, dropping to 320
Pin 4:50mV building up to ~150 mV before dropping back to zero and climbing again.
Pin 5: Much the same, gets to about 200mV, then drops back to 0 and starts climbing again.
Pin 6: fluctuating readings, but never leaving the mV range. (maybe 200 mV max.)
Pin 7: Same as Pin 5
Pin 8: started out at 4.2 volts positive, then went to negative 13 volts after warm up
Pin 9: Same as Pin 5 and 7

I THINK...you are measuring BACKWARDS...Otherwise...you have NO plate voltage----and I do NOT think that would result in a no-brightness condition. but--maybe I am wrong.

let's asume you ARE measuring backwards..This makes more sense. THEN...you are getting 320 colts on the PLATE-----and that is likely WAY too high.

I see only - 8 volts on pin 3 (8). this sounds WAY too high to me....tube would NOT draw any current and WILL keen cathode of CRT cut-off.


HERE...accd. to Sams is what your voltages SHOULD be..on that tube.:

Pin 1--cathode--.5 volts

pin 2--control grid--- -2.5 volts..

pin 3-, pin 9--grounded.

pin 4, 5 --filamant.

pin 6-ground

pin 7--plate--235 volts. you are measuring WAY too much here.

pin 8--screen grid--115 volts. There is a 22K resistor here--r-70. CHeck to see if it is open or high in value.

Off of the grid pin--pin 2--there is a choke--l15--should read 10 ohms. Ths is paralleled by a resistor--R65, shoukd be 4.7K.

SOMETHING..is OPEN here.

ALSO..On the OTHER SIDE of L-15 is the delay line. COUld be open. if not...on the other sid eof it...is ANOTHER choke--L-12. 5.2 ohms. Then...it goes to a transsitor--Q5--the 2ND video amp, collector pin. SHould read 11.6 voilts or so. ,Base should read 16 volts, emitter 16.5 volts. lThis is a PNP transsitor---it relies on a differential i voltages on base to collector--toi conduct. base goes CONTRAST control--which is connected to 21 volt line.through R-61 18K.

Off of the grid pin--pin 2--there is a choke--l15--should read 10 ohms. Ths is paralleled by a resistor--R65, shoukd be 4.7K.

SOMETHING..is OPEN here.

ALSO..On the OTHER SIDE of L-15 is the delay line. COUld be open. if not...on the other sid eof it...is ANOTHER choke--L-12. 5.2 ohms. Then...it goes to a transsitor--Q5--the 2ND video amp, collector pin. SHould read 11.6 voilts or so. ,Base should read 16 volts, emitter 16.5 volts. lThis is a PNP transsitor---it relies on a differential i voltages on base to collector--toi conduct. base goes CONTRAST control--which is connected to 21 volt line.through R-61 18K.

You sure you're looking in the right SAMS? because there's no R 61, 65, or 70 anywhere near the 12HL7 tube. Also to my knowledge this TV does not have a contrast control... or at least I can't find it.

This set is a TRUE definition of a HYBRID set.

Here you have a set with most of the low-level stages SOLID_STATE--including an IC_-for sound det-pre-amp and a power transistor for the output.

ALL of the IF and AGC is SS. Most of the video is SS..--save for that 12HL7 V-out tube..

Most of the chroma stage--Except fot the 6MD8 chroma amp tube is SS too.

Only the horiz and vert stages are mostly tube. Tuners are SS too.

The FINAL Hybrid Sylvania color set--the D-16, evidently dispensed with the HV rect and shunt reg tube..replacing them with a TRIPLER

Scratch the part about the TV not having a contrast control. i just discovered that what i thought was just a missing nameplate is a door with 4 more controls I'm going to try adjusting those and see what I get.

Edit: adjusting the contrast control makes a slight difference.

Looking at sams for D-12-8. VERY likely to have same video layout as yours.

in FACT...I SEE 2 of the resistors now..

R65..next to l-15--left side of that coil--L-15, maybe in FRONT of it..

R-70--in FRONT of 12HL7 tube--to the RIGHT of it..

R-61 is on SS board--FRONT of set...behind a little black transistor..

Your delay line is M4...should be on the side of the board with the 12Hl7. If it is open or shorted...it WILL kill the video..and NOT overload anything. Check it..it COULD have been broken off or such. if OPEN...you CAN bypass it--it's purpose is to delay the video a few microseconds...to ensure it does not get to the CRt before the chroma--which takes longer to process. If bypassed...it will NOT look quite right...but WILL tell you what you need to know...

Delay line... is that what that long cardboard tube is?

Indeed it is. It should show continuity between the sides....NOT to ground. I do not have an ohms value--but I do not expect it will be over 100 ohms or so...but it should NOT show low to ground..

So it shouldnt read, uh, close to 2,000 ohms then? I think I found the problem. I'm going to bypass it and see what happens.

Hey! That helped! The picture is still dim and blurry, and the focus control doesn't help, but I was able to connect my DTV box and get the horizontal and vertical adjusted.

You can see in the attached image how blurry it is. That's supposed to be a box that says "No Signal"

Ok....so you have an open delay line. not the most uncommon thing to see.

Your tube likely is not too bad. BUT...you sem to have A focus voltage problem too...

Focus comes from the flyback--is rectified by diode X6---and then goes through a couple of resistors--including one to GROUND_-to keep it from going too HIGH-..-R-155, a 66 meg resistor. There is also R-154, a 4.7 meg resistor--in line to the focus pin to the tube. Sams says 4KV for focus...but this is an AVERAGE voltage...it may be higher or lower depending on the CRT. The focus control is a coil--tied between boost and boosted boost ans the focus voltage...there are a oair of resistors that parallel the windings--if these are off much---it WILL mess up the focus. R-161, 162. 8.2K. There is a cap, c-110, in line to that focus coil--likely ceramic--130PF, if shorted--it would mess up focus too.

FYI--with the delay line bypassed..you will NOT get perfect video--but the FOCUS should be better than that...

Yeah i'll worry about the delay line, and the thermistor, and everything else after I see if the CRT still has life in it... That image I posted was with the drive controls, brightness and contrast at max...

Oh and correction about the focus control. It does help, but that's the best I can get the image.

EDIT: Something else I should mention. Since bypassing the delay line, the brightness control is now working in reverse. as in the image gets brighter the lower I set it.

I decided to make a new video showing what the TV is doing now.
http://www.youtube.com/watch?v=7qnArBCVGGQ&feature=youtu.be

The screen controls still do nothing, but I have a good hint that the CRT is okay. Setting the color drive controls to minimum still produces a visible image, now that the delay line has been bypassed.

However the image is still very dim. I'd like to solve this issue first before moving onto focus. I think I should go back to the 12HL7 and measure the voltages again. I'll do that after lunch unless you guys have any other suggestions.

EDIT: okay, new 12HL7 voltage readings taken using the same clockwise measurement as last time. Screen and color drive controls are set to about mid point.
Pins 1,4,5,6 and 7 have negligable mV readings.
Pin 2 starts off at 350, then drops to 146 volts
Pin 3 starts at 355 volts, dropping to 250
Pin 8 is the biggest change. It started at 0.5 volts, went up to 2 volts, then dropped to around -200 mV
And pin 9 started at 0 mV, slowly climbed up to 200 mV before dropping back to 0 and starting over.

Also I think that 12HL7 tube is running hotter now.

First the 12HL7 shows it is cut off IMHO which gives a
high plate V so high CRT cathode so dark pix.
The 12HL7 is a 12 V tube BUT the filament is tapped so you can
run it at 6VAC in a series set.
You should get apx 6 VAC at pins 4 & 5 to ground.
Pin 6 must go to GND. Its the tap.
Next change the 12HL7 its fast & easy & eliminates it.

BTW looking at my Sams under better light I see tiny
check marks around the drives & other plate components.
Someone may have been chasing the same problem. They
DID NOT do what they should have, write down the sympton
& cure, ass hole............
Gotta put the feed bag on, more later.

73 Zeno:smoke:

Next change the 12HL7 its fast & easy & eliminates it.



I need a spare 12HL7. I can order one on eBay, they're cheap enough. However before I do that, should I check to see if anything else might be open?

While waiting for 12HL7 check from Q4 & Q5 over
to the 12HL7.
Also R147 & 153 at 6LR6 grid 1.
I would also price a 40 KV HV probe, you may need one
for the focus problem. Can discharge CRT with it also.

73 Zeno:smoke:

...

While waiting for 12HL7 check from Q4 & Q5 over
to the 12HL7.
Also R147 & 153 at 6LR6 grid 1.
I would also price a 40 KV HV probe, you may need one
for the focus problem. Can discharge CRT with it also.

73 Zeno:smoke:

Little confused by this. Check what from Q4 and Q5? Voltage to ground? Continuity?

I'll hunt down R147 and 153 when I have some time, probably Monday. Depending on whether or not they're good, I'll see about acquiring a 12HL7

Check voltages. Also especially any high ohm resistors over
say 50 K ohm. Test coils, IIRC there are 2 of them. Test the transistors also.

Also as stated early Sams gave things there own designations. Parts
on a PCB may not line up with the Sams numbers. Also a factory ( FSM)
service manual may have different numbers. This changed it latter
years but dont remember when. Just gotta live with that.

Little confused by this. Check what from Q4 and Q5? Voltage to ground? Continuity?

I'll hunt down R147 and 153 when I have some time, probably Monday. Depending on whether or not they're good, I'll see about acquiring a 12HL7

Okay, I believe Q4 and Q5 are supposed to be the transistors for 1st and 2nd video amp. I had a few minutes to do some testing so i tested the voltages for the 2nd video amp transistor: (the one closest to the delay line)

Emitter: 9.6 volts, raising to 10, then dropping to 9.8 upon warm up.
Base: 14 volts, going to 15, then dropping to 14.5
Collector:14.9, going to 15.7, dropping to 15.1

If need be I'll get voltages for the 1st video amp transistor later.

Remove and test those transistors with your DMM on the "diode function".
I recall GE sets of this vintage (KE chassis) with similar symptoms from shorted video driver transistors.

The emitter and base voltages should not be more than 0.6 volts difference.
It may be shorted by the look of those voltages unless you have E and C mixed up.

It may be shorted by the look of those voltages unless you have E and C mixed up.

I obtained the voltages by testing one pin at a time, using chassis ground for the DMM's negative lead. The transistors has EBC labeled for the pins. I doubt I messed up the order.

Pulled the transistor and tested it using the diode function:

Collector to base: voltage going one way but not the other.
Emitter to base, same reading. Voltage one way but not the other.
Emitter to collector, no reading either way.

Edit: transistor for the 1st video amp tests the same way.

I have a new 12HL7 coming in the mail. Should have it by Monday. See if popping that in makes a difference.

Okay I received the new 12HL7 in the mail today. Popped it in. No change.

Brightness control still operates in reverse. Picture is still dim and unfocused.

The only thing I can think to do from here is pull the neck socket again and test the voltages there.

There's been a new development!

I am now the owner of an EMC 213 tube tester! So I've been testing the tubes in this TV, well at least the ones listed in the user guide. This tester was made in 1964, this TV is a bit newer then that so I couldn't test some of tubes. However I discovered something odd.

The HV rectifier tube that's in this set is a 3A3B.

The TV's schematic calls for a 3CU3.

Could this be a contributing factor in why the image is dim and/or blurry?

Can't test the 3A3B unfortunately. It's not listed in the tube chart for this tester.

There's been a new development!

I am now the owner of an EMC 213 tube tester! So I've been testing the tubes in this TV, well at least the ones listed in the user guide. This tester was made in 1964, this TV is a bit newer then that so I couldn't test some of tubes. However I discovered something odd.

The HV rectifier tube that's in this set is a 3A3B.

The TV's schematic calls for a 3CU3.

Could this be a contributing factor in why the image is dim and/or blurry?

Can't test the 3A3B unfortunately. It's not listed in the tube chart for this tester.

I actually have the 3A3 tube and also the 3CU3 tube as well I believe and I'm surprised the tester I sent you can't test the 3A3 tube...:scratch2:

Scratch that, Just took a look at the chart and the tube tester I sent you CAN test a 3A3 tube, generally tube tester charts don't put the letter suffixes after the tube designation because they're all the same tube just different heater warmup times.

Need to find out of that tube is a proper substitute for the 3CU3 that should be in there.

Need to find out of that tube is a proper substitute for the 3CU3 that should be in there.

The 3CU3's Subs include 3AW3, 3CV3, 3CZ3, and 3DC3, but not the 3A3, so your issue might have something to do with having the wrong tube in there... :yes: :scratch2:

..... generally tube tester charts don't put the letter suffixes after the tube designation because they're all the same tube just different heater warmup times.

Not so - the 3A3C is an improved type with reduced X-ray protection. Heater characteristics are the same as the 3A3. The glass and plate were improved for better X-ray protection, much like the 6BK4 upgrade to the 6BK4C/6EL4

Electrically the same for tube testing, but with most testers putting only about 100V across the tube, not a conclusive test. We checked HV rectifiers with GE's suggested circuit, also used for Focus rectifiers - you can't check them accurately without a fairly high voltage.

Not so - the 3A3C is an improved type with reduced X-ray protection. Heater characteristics are the same as the 3A3. The glass and plate were improved for better X-ray protection, much like the 6BK4 upgrade to the 6BK4C/6EL4

Electrically the same for tube testing, but with most testers putting only about 100V across the tube, not a conclusive test. We checked HV rectifiers with GE's suggested circuit, also used for Focus rectifiers - you can't check them accurately without a fairly high voltage.

I see, so then the 3A3 tube test setup on the tube tester I just sent him and mine as well wouldn't be able to test the tube that he's asking about then, or would it?

All the suffixed tubes will test with the settings of a non-suffixed tube.

My comments were aimed more at the incorrect statement made about the suffixed tube differences, it's X-ray protection, not heater warmuptime as you mentioned.

All the suffixed tubes will test with the settings of a non-suffixed tube.

My comments were aimed more at the incorrect statement made about the suffixed tube differences, it's X-ray protection, not heater warmuptime as you mentioned.

The "A" designation on the 12AX7s and what not do refer to warm-up time that's mainly what I was referring to, I was mainly referring to the fact that the suffixes in the tube designations referred to a revision of some sort in the tube in general, not just heater warm-up time I was using the heater warm-up time as an example of what some of the designations could mean.

Guys it's kind of a moot point. Doesn't matter if that 3A3 is good or not because it's the wrong tube for that TV.

And I'm hazarding a guess that the wrong rectifier tube could further explain the dim, blurry image

Guys it's kind of a moot point. Doesn't matter if that 3A3 is good or not because it's the wrong tube for that TV.

And I'm hazarding a guess that the wrong rectifier tube could further explain the dim, blurry image

I agree, I was mainly just trying to make the point that the tube tester I sent you isn't as obsolete as you thought it was, that's all. Like I said I'll still check my tube stash out at home for the tube you need or its substitutes and get back with you about it. I had a birthday party to go to earlier and I also had to repair one of my tires because it had 3 nails in it and was low and I was checking into getting some new tires for my car as well so I won't be getting home as soon as I thought I would today. Don't worry I haven't forgotten about you! :thmbsp:

EDIT: I just looked through my tube stash and had two boxes labeled 3AW3 (which is a proper substitute forthe tube you need) but that's all it was, just the boxes, the tubes inside them weren't even close to being 3AW3 tubes, one was a 1B3GT tube (which I'm not sure why a tv repairman would put a 1 Volt tube in a box for a 3 volt tube and is definitely NOT a suitable substitute for the 3AW3 let alone a 3CU3, and its not even the same filament voltage) and the other tube was a 3DB3, which I guess is a substitute for a 3AW3 and also a 3CU3, If you want the 3DB3 tube I have (I'll test it first to see if its any good)I can mail it off to you, for the price of shipping.

Well I tested the 3DB3 tube I have and it almost pegged out my tube tester on the good side of the meter on both the grid leakage and emissions tests. I'm kind of starting to see a pattern here, its almost like whoever owned this tube caddy before me was apparently a dishonest repairman and replaced tubes inside TVs and radios that didn't need replacing just so he could upcharge his customers for repairs that weren't needed, kind of like how auto mechanics work sometimes... :scratch2:

Take your time. I'm in no major rush. :)

That Sylvania TV has a very nice cabinet. I have two end tables and a coffee table in my apartment with the same type of legs as your TV has. That design must have been popular in the '60s-'70s, and made a comeback in the late 1990s when I bought my furniture (I was moving to an apartment, the one I live in today, at the time, and wanted to make a fresh start).

That your TV's cabinet has absolutely no scratches whatsoever on top is wonderful. Your set's former owner(s) must have taken extremely good care of it, which is good. I've seen console TVs with all manner of dust, dirt, scratches, etc. on them (I've owned a few, mostly trash finds; they stayed in the basement of my former home, of course), and again, your Sylvania console, as scratch-free as it is, is a sight for sore eyes.

Back on topic: I'm not sure what tube substitutes for a 3A3, as it has been years since I worked on TVs of any kind (my apartment is very small, so I limit the little restoration work I do to small radios). However, the list of subs for the 3A3 I saw in another post seems quite comprehensive, so one of them should work.

I'd be extremely careful with a tube such as a 3A3, as the filament of this tube carries extremely high voltage (especially in color TVs), on the order of kilovolts, not just three volts as the type designation would have one believe. These tubes get their filament voltage from a single turn of exceedingly well insulated wire wrapped around the laminations at the base of the flyback transformer.

Well I tested the 3DB3 tube I have and it almost pegged out my tube tester on the good side of the meter on both the grid leakage and emissions tests. :

No grid leakage in a 3DB3? Amazing, considering it doesn't have a grid...:thmbsp:

No grid leakage in a 3DB3? Amazing, considering it doesn't have a grid...:thmbsp:

Well Then I'm guessing that the Emissions test would be the only test that would apply in this case then, which in that case it still nearly pegged out my tube tester on the good side of the emissions test, which means it's a perfectly good tube yet, which means that what I said about the previous owner of my tube caddy being a greedy/shoddy repairman that replaced perfectly good tubes in radios and tvs just to upcharge his clients still would apply here because most of the tubes I found in my tube caddy were previously used tubes that still tested like new on my tube tester with quite a few NOS tubes thrown in for good measure.

No worries Captainclock. 3CU3's are available on ebay for a few bucks including shipping.

Dont trust a tube checker. It does not test the tube under
normal use. The are not run at say 200 mhz as an RF amp
or 1000 V spikes like a horz output. Some tubes will
check bad & work fine & some check good & not work at all.
Use it as a helper but never the last word.

BTW We had a very nice B&K checker but never used it.
It was for the customers. Biggest cash cow in the shop.
What we did have was a filament tester. Did 7&9 pin minis
& compactrons. Useful to find an open filament in a series
string set without easy access to the bottom. Great for AA 5
radios too ! Cost abt $10 back then.

73 Zeno:smoke:

Update: I have a new 3CU3, but I don't know if it solves my problem because I have a new problem now.

I think I fucked over the shunt regulator tube.

When I got my tube tester, I decided I was going to test every tube in the chassis. You might recall I tried to remove the shunt regulator tube before and couldn't. I eventually found out why.

After pulling on it, probably harder then I should have been, I found that it was being held in with a retainer clip. http://alamak.com.sg/i/SG/doh.gif

So I removed it and put it in my tube tester. The tube is a 6BK4C and my tester has settings for a 6BK4, so I used those settings. Emission almost immediately jumped to max, then the needle started jerking quickly. Then a purple glow appeared near the bottom of the tube so I cut power. Not having another 6BK4 I put this one back in the TV.

So I put in the new 3CU3 and power on the set. As soon as HV comes up I hear rapid arcing, then the sound goes weird. I immediately cut the power.

I suspect I messed up the 6BK4. Can I run the TV without the HV regulator tube in it, or would that be a really bad idea?

Don't run it without the reg unless you are metering the HV. The HV can easily go above it's ratings without that tube, and if HV goes above ratings stuff like the fly can be damaged.

Got it.

So that purple glow I saw when I tested that tube, what did I do to it?

Purple glow is usually gas leaking into the tube.

Thats what I was afraid of.

I pulled pretty hard on that tube. The retainer clip was attached to the plastic base. I think I pulled the base too hard and cracked something.

Welp... live and learn. Now to hunt for a new 6BK4C

Okay, I now have a new, (well, NOS) 6BK4C, Sylvania branded at that. Came in the original box which I will be saving.

Popped it in. Now the TV has the right rectifier tube and a new shunt regulator tube.

And...

It looks like the image got dimmer. Brightness control seems to have no effect now. Contrast has a minor effect.

More frighteningly, about 30 seconds after it warms up there's a single arc of electricity. Something's now arcing inside the set.

I don't think I want to continue working on this. I think it's a lost cause at this point.

Okay, I now have a new, (well, NOS) 6BK4C, Sylvania branded at that. Came in the original box which I will be saving.

Popped it in. Now the TV has the right rectifier tube and a new shunt regulator tube.

And...

It looks like the image got dimmer. Brightness control seems to have no effect now. Contrast has a minor effect.

More frighteningly, about 30 seconds after it warms up there's a single arc of electricity. Something's now arcing inside the set.

I don't think I want to continue working on this. I think it's a lost cause at this point.

Unless you get a CRT tester on there and the CRT tests bad, it is FAR from a lost cause.

If that set was on my bench I could probably have it working right in a weekend.

It is possible the HV REG circuit is misadjusted or defective. Try running the HV REG control through it's range. If that does not yield improvement, then pull the top connector off the HV REG tube and stick it in a glass jar so it can't arc, then run the set that way for no more than a minute after HV comes up, and let us know how the screen looks.

IIRC you had gun bias issues that were never properly addressed...Revisit that.

You also need an HV probe to get a proper measure of the HV so we know the health of that system.

Yeah that's the thing. I need an HV probe and a CRT tester before I can really proceed on this. Finances are such that it took over a month before I could spare the $5 needed for the new regulator tube.

The bias issues were resolved i believe by jumpering the delay line. In any case I think I'd rather give this set to someone whose better equipped to work on it.

So this is what I'll do. I'll keep the TV around until the new year and see if anyone here is willing to come get it. If they are, then they can have it for free and I'll even help them load it.

Otherwise I'll probably strip the tubes out of it and scrap the rest.

Well I'm glad to say this set found a new home!

Glad it's going to a good home, and not being scraped!

Tube TVs require plenty of service equipment, knowledge, and patience.....My first set was a real dog that other techs tried and gave up on, but I set it aside for the better part of a decade, learned on easier sets, and came back to it this week Finally getting it going yesterday.

.My first set was a real dog that other techs tried and gave up on, but I set it aside for the better part of a decade, learned on easier sets, and came back to it this week Finally getting it going yesterday.

Well turns out letting this one go was a wise move. Just heard from the person I gave it to that the CRT is very weak. So... well it explains a lot and I guess it was to be expected.

Well turns out letting this one go was a wise move. Just heard from the person I gave it to that the CRT is very weak. So... well it explains a lot and I guess it was to be expected.

Perhaps it was a good move. I've (reluctantly) thrown new CRTs in chassis with less stellar reputations than that one though, and if that one were mine I'd have stuck it out.

The irony is I was told the chassis basically functions. So I fixed most of the chassis issues, it's just the CRT is way over the hill. The guy I gave it to will try to rejuv it sometime in the future. For now however I think that closes this chapter.

I have recently made a lot of progress on this nice Sylvania hybrid. I got this set from Justin “MRX37” after he rescued it. Justin got the set from dead to basically functioning, he replaced the shorted power supply diodes, and a resistor. Problems then remained with occasional HV arcing, very poor, out-of-focus video, and suspected delay line issues. At this point, Justin offered the set for pick up, I got in touch, and took the offer, to see what I could maybe accomplish, to try and get the set going again! This required solving several issues. The delay line was ok, except for a bad connection, which I repaired. The HV arcing, was caused by a crumbling HV Regulator Tube plate cap assembly, which I salvaged from an RCA CTC-38 parts chassis, to replace the crumbling one! Now, still very bad no focus video. I had checked the CRT, it’s the original Sylvania RE25AJP22A tube, which was dead on emission, all three guns. I let it “cook” awhile, that gave blue and green guns some emission, not much, and virtually no red gun action. I rejuvenated the CRT, and got it usable again, with some cut-off, but who knows how long it may last. The screen RGB controls had almost no effect, I removed and cleaned the combination potentiometer outfit, which was as I suspected, just full of tin whiskers! That restored control of the screens, and next came the almost no focus issue. I had to replace the focus rectifier diode stick, which then restored focus. Now, the color osc. kept loosing sync, which turned out to be a bad 3.58 osc. crystal, I replaced that, and next, the only 6GH8A tube, which was intermittently shorting, in the osc. section, this restored the color, properly. Now, some vertical sync., and linearity troubles began to surface, that required replacement of some caps in the vertical circuit. Of course the VHF Tuner was very much in need of cleaning, as well as other controls. After all that, you see the results in the photos, it looks much better now! I still have to solve an issue with the solid state audio circuit, seems to be heat related, and the audio output transistor is thermally sensitive, as well. There may also be a bad cap or three in the audio circuit, I will get to this after I purchase the audio transistor. My sincere thanks goes out to Justin, for dragging this set home to save it, and his initial repair of the power supply circuit, and for passing the set on to me, (and helping to load it), to see what I could do with it. This is the first Sylvania of this type that I believe I have ever serviced. I cannot recall more than one or two Sylvania color sets, from back in my TV Shop days! I “crafted” the (temporary, I hope), Nameplate / LOGO Badge, that is missing from the controls door, this is the only place that “Sylvania” appears on the front of the set, so it needed a name!:)

Well son of a B... Looks like this thread got a happy ending!

And my name's not Justin, but that's okay as I'd rather not have my real name put out there.

The set's looking good!

is this the d12 or d16 chassis?with a 25a crt probably d12.those were very good sets and this was the beginning of sylvanias golden era.1969 to 1980 was their pinaccle

I can give you a picture of what a beat up, faded aluminum pencil box cover for one of those looks like, but I won't sell mine (nor do I think you want it).

Ooops, I apologize, MRX37, I remember your name, I didn't realize until I read this, that I typed the wrong name! A middle-age moment, for sure, but not to worry, I won't make the correction public! :-) Many thanks, this was a several hours project, and challenge, but turned out nice. I still have to revisit the audio problem.

Thanks, Tom! I would like to see a picture of the "badge" on your Sylvania! They must come un-glued, and fall off!

is this the d12 or d16 chassis?with a 25a crt probably d12.those were very good sets and this was the beginning of sylvanias golden era.1969 to 1980 was their pinaccle

Yep. D12 chassis.