hey all i have not got started on this silvertone ctc12 clone yet to find out why the hv jumps up and down with scene changes and the cathode current jumps as well. i will be checking the 390k resistor at the blanker tube to ground since it was said to do this if the resistor is out or the ground trace is bad. so with all the talk about the low hv on that ctc5 does this sound like anything to anyone? 24kv at the crt but it jumps around with scene changes as low as 19kv and with that the cathode current to. this set was not right from the beginning with the hv. all the caps in the horiz section was changed and more. i changed probably more caps then i should have. shunt tube is new , rect tube, resistors in the hv adjust string checked good, resistor at the 6dq5 was changed. the crt bias has to be all the way counter because if i raise it just a touch the whole screen turns to blurr and the hv takes a huge dive, any ideas befor i go ahead and look at something that will get me nowhere,lol,lol....:smoke: :D

Sounds like a bad brightness control (or that bias pot you mentioned) to me, the blooming is caused by excessive current draw so if the screen brightness is all over the map that's where I'd start.

What's the model number??

i think its stamped 3129 or 28 i think its 1963 with the ctc12 clone. its the one on this page on the left.

If it's a CTC-12 clone then you will not have the same problem with the blanker tube bias effecting the HV production, that did not happen until the CTC-15. It was a backup to runaway HV if the shunt tube failed.

If it has a 1.5 meg resistor from the control grid of the HOT to the term TT on the chroma board, then you have the blanker tube bias issue.

If it's a CTC-12 clone then you will not have the same problem with the blanker tube bias effecting the HV production, that did not happen until the CTC-15. It was a backup to runaway HV if the shunt tube failed.

If it has a 1.5 meg resistor from the control grid of the HOT to the term TT on the chroma board, then you have the blanker tube bias issue.

the 12 schematic shows the same 390k resistor off pin 2 of the blanker tube just as the 15 and 16.

I give up

Ok first forget the clone crap, thats something the super elite do so they have spare parts.

Whats the model number, its going to be something like 528.555555 and it will be on the back.

It may not be a clone at all, it may be a spinoff...how about that?

We need to start with the right model number and schematic and stop telling the tv what it is.

Ok first forget the clone crap, thats something the super elite do so they have spare parts.

Whats the model number, its going to be something like 528.555555 and it will be on the back.

It may not be a clone at all, it may be a spinoff...how about that?

We need to start with the right model number and schematic and stop telling the tv what it is.

ok the chassis dont have a number on it but could use this number from the sams which is this chassis, 528.61110 hope this helps. and as far as this bias problem i had read a thread here on karma about this resistor from pin 2 of the blanker tube to ground and yes it was said that it started with the 15 chassis but no one knew if possibly it went for the 12 unless the sams was looked at for the 12 and it shows just that resistor in the very spot from the 12 to 16 chassis and there is no 1.5 meg resistor that i found on the 12.

Look very close at the boards, most of the time sears has a little metal tag soldered into the board facing back with the number stamped into it. It looks like a little flat capacitor or something.

Look very close at the boards, most of the time sears has a little metal tag soldered into the board facing back with the number stamped into it. It looks like a little flat capacitor or something.

ok ill have to get the chassis out and find this number. i was just fishing for maybe something i could have looked for as a simple fix without pulling the chassis.

You dont have to pull the chassis out. Its sticking up out pf the board facing back at you

Im working on getting our dearest timmy to get me a verified model number so I can get the correct sams and post a photo of the area of interest.
I went through a bit of trouble to compile a fairly complete set of sams and its ridiculous to be guessing what resistors it may have and what it may be a clone of. It takes me fairly little effort to grab the correct schematic and scan it.
We already left poor davewm in the oven to long on this one getting sidetracked on what might be

ok dan heres the chassis number 528. 61115 there was a paper tag on the back. i also checked the 390k resistor from the grid of the blanker tube to ground and its 248k its down from what it should be, dont know if this is a factor.

Very good, do you have a copy of 655-2?

Very good, do you have a copy of 655-2?

yes that is the very folder i have 655-2:D:D

i dont know what this means but bwhen i raise the bias the rect tube filiment dims and the whole screen goes blurry and the hv drops way down.:no:

Ok I will look when I get home.

i dont know what this means but bwhen i raise the bias the rect tube filiment dims and the whole screen goes blurry and the hv drops way down.:no:

You are overloading the HV or there is lack of HV capacity. What is the screen voltage on the HOT and what should it be?

Hmm... Gassy CRT? I never had that symptom. Be interesting to find out what it's about. :yes:

screen volts on the hot ill need alittle help there where to measure but the rgb screen drives are to be 620-680 volts im getting around 600volts bg drives are to be 290v im getting 250-280 volts there. i also pulled the hot and measured the cap volts and thats 415v. horiz tube 6fq7 pin 6 is 280 volts. focus volts are 4500kv.

No No. the screen voltage on the horizontal output tube. Its usually around 190v. Its usually on the right side of the tube on the sams, opposite the grid which should be around -45v.

stromberg6; this is a fairly common problem on these old color sets. If there is excessive drive to the horizontal output tube or a bad capacitor, even a defective focus control causing the HV to run inefficiently it wont be able to keep up.
Kinda like if a car has a restricted exhaust it falls on its face when trying to climb a hill.
These can be difficult problems to diagnose because its half way working.

Some of the confusion with this thread is a problem thats related to the ctc16 chassis only. On the 16 there is a very thin trace on the edge of the board that fails and causes excessive drive to the output and results in lack of capacity.

ill try to get to those terminals the sams shows -50v and the other 140v. i did check cathode current its at 200ma and the hot is not red plating. ill check those voltages.

ok the hot screen volts sams shows -50v and i get -55.9v and the other sams shows 140v i get 140v. i had changed all the red caps in and around the horiz and many more.

55 is kinda high. I bet once its fixed it will be -50 @220ma and will work right. Yes 5 volts can make that much of a difference. Hang out till I can get home and look at the sams.

55 is kinda high. I bet once its fixed it will be -50 @220ma and will work right. Yes 5 volts can make that much of a difference. Hang out till I can get home and look at the sams. i checked these voltages with the set running normal i just put 2 wires in the socket and put the tube back in and waited about a minute then i checked.

No No. the screen voltage on the horizontal output tube. Its usually around 190v. Its usually on the right side of the tube on the sams, opposite the grid which should be around -45v.

stromberg6; this is a fairly common problem on these old color sets. If there is excessive drive to the horizontal output tube or a bad capacitor, even a defective focus control causing the HV to run inefficiently it wont be able to keep up.
Kinda like if a car has a restricted exhaust it falls on its face when trying to climb a hill.
These can be difficult problems to diagnose because its half way working.

Some of the confusion with this thread is a problem thats related to the ctc16 chassis only. On the 16 there is a very thin trace on the edge of the board that fails and causes excessive drive to the output and results in lack of capacity.

Thanks for the explanation. So many things to go screwy in a horizontal output system that are related. Saving the comments for future reference. Thanks! :yes:

Thanks for the explanation. So many things to go screwy in a horizontal output system that are related. Saving the comments for future reference. Thanks! :yes:
Yea exactly. Dont mention gassy crt to timmy or he will be at the local pharmacy looking for a fix.
Lets start by verifying the HV system has enough capacity.

Ok lets fix this thing....
The first thing I will say is the 390k resistor has nothing to do with it on this set. Its not even tied together like that. The thing calls for 200ma, if thats what you have and the screen is 140v I would wonder if you got the bias and the screens cranked up way to high. Check the HV reg current (it has a jumper) and see if you are getting the 1ma with a dark screen.
http://boxcarcabin.com/timmyss.jpg

Ok lets fix this thing....
The first thing I will say is the 390k resistor has nothing to do with it on this set. Its not even tied together like that. The thing calls for 200ma, if thats what you have and the screen is 140v I would wonder if you got the bias and the screens cranked up way to high. Check the HV reg current (it has a jumper) and see if you are getting the 1ma with a dark screen.
http://boxcarcabin.com/timmyss.jpg

ok, the crt bias is down ccw all the way the R G B drives are not even a quarter up they are very low, and the G B drives as well are really low. because i know if they are to high then sometimes you get the lines running across the screen like i have now faint but i see them and they each are a color.there are only 2 sets of lines running left to right and fades toward the middle. could you tell me where or what to break to check this hv reg current with the meter? would this be under the chassis or could i get to checking it behind the 6bk4. as far as a gassy crt i have looked in the dark for the dreaded glow of death in the neck and never seen any. as far as the crt testing, on the bk440 tester at 5v after a minute the needle bearly makes it close to the 200 mark which 200 reading or more is good. at 6.3v the needle just makes it over the 200 mark. at the color setting next to 6.3v it may be 7v i dont know it shows very good so i really dont know if the 6.3 reading would infact be good or if the crt is tired well then it is what it is if everything else checks out ok. the jumper in the sams for hv reg current is that jumper closed or is it opened all the time? the reason i ask is that jumper if i remember correctly was under the chassis and i think it was closed by means of a component where on the tie strap one leg was long and was tied together that way and i may have opened it thinking it was not to be closed and that it was open to put a meter across.should this spot be closed? i will look under to see if i had left it opened or closed. because i remember open or closed the set worked. ok 1ma bright down.:smoke:

IF for some reason the jumper was removed and left off, then you will have NO hv regulation, and you may have too high HV since the idea is the shunt tube should conduct at all times (bright and dark screen). How much current it shunts depends on the HV pot setting AND the overall load on the HV system.

hv is all over with scene changes, clearly hv cant keep up with demand for whatever reason so far.

hv is all over with scene changes, clearly hv cant keep up with demand for whatever reason so far.

I am not sure what you mean by "can't keep up" but if you mean the HV is not regulated then then the reason is:

1) HV shunt is not operating correctly (a missing jumper would for sure do this as an example)

2) there is not enough HV in reserve (so the shunt has nothing left to shunt, and the HV drops) this can be a weak tube or other problem in the HV system.

3) CRT load too high from incorrect setup or defect in circuit or bad CRT.


Answer the following please (in order)

What is the HV (in kV) with the shunt tube cap off and the brightness all the way down? Make sure the tube cap is not near anything as it will arc.

replace the shunt tube What is the HV now(in kV)?
brightness up
brightness down

with brightness down does the HV adjustment pot have any effect on the kV?


Its important to answer the all the above questions prefer in that order asked to try and figure out whats going on. It would help if you would quote this and answer each question.

i have done this in the beginning and the fly was said to be ok so the reg tube cap off was around 30kv alot of hiss. cap back on 24kv with the hv adjust at max if i turn it down it will lower the hv. bright up or down the hv adjust does work but to get just the 24kv it has to be maxed.

well the jumper was closed so i broke it put a meter in and im getting 5ma and hissing in the cage and sometimes an arc at the crt neck with the brightness not all the way down, the ma goes up if the bright is all the way down. ok im lost . i forgot to mention with bright up i get 1.2ma- 5.3ma it jumps from both readings.

That does not sound right. the shunt should be around .5ma on full raster, too about 1.5ma full dark. I suspect your are not reading something right or your meter is not working correctly if you are seeing 5ma

you need to put the HV meter on the CRT, put the current meter in the jumper and watch the HV vs Shunt tube current as you adj the brightness on a raster.

Set the HV pot for 24kv then adj the bright up and down note the shunt current, if it goes up as the crt goes dark and goes down as the crt brightness increases, then the shunt is working as it should.

If the above is correct (shunt working as it should) then you need to go back and recheck the HV setup, starting with the cathode current dip on the eff coil.

when you get all that sorted out and have the correct meter readings (.5-1.5ma shunt). Then you can restart the trouble shooting. One other thing, assuming the HV is ok is the focus voltage can cause what looks like blooming including complete darkness on the CRT. The pin and or the socket at the CRT sometimes fails from corrosion.

oh I would recommend an analog meter if you are not using one. Something like a simpson 260. I don't like to read current readings that move quickly with DMM.

also try a new HV rectifier tube.

well i did use a fluke digital meter and i do trust it but lowering the brightness is causing arcing and the ma does raise up the lower i put the brightness. so ok ill follow the above again. and i did have the meter in the ma setting. all i can do is leave the hv adjustment where it is now which is at max 24kv is all i can get. as far as the blooming with the hv probe in place if i just move the crt bias a touch it blooms and the hv drops dramatically.

where exactly is the arcing? you really want to avoid that.

I cant see enough of the schematic, but need to know where R135 goes.

some sets tie in the video signal from the video out tube into grid of the shunt. This is done for more rapid adjustment of HV.

Make sure C99 is not bad if you have HV reguation problems.

ok here goes i have an analog meter and hv probe in bright down 24kv and not even half ma on the meter bright up around 23kv and even less then half ma. the arc was happening at the crt neck just a couple of times.

where exactly is the arcing? you really want to avoid that.

I cant see enough of the schematic, but need to know where R135 goes.

some sets tie in the video signal from the video out tube into grid of the shunt. This is done for more rapid adjustment of HV.

looks like r135 1.5 meg goes from grid of reg tube to hv adjust pot and horiz lin. c99 cap was changed its a .00
33 ceramic. the meter i used i know now that it has 5ma increments so the amount it moved i think its safe to say that i got .5 and 1.5 ma because it never got near the 5ma line.

ok now we are getting somewhere. try a new HV rectifier tube 1st. then check the sams see if it mentions adj the horz eff coil 1/4 turn to bring that shunt tube up to spec (.5-1.5 bright to dark). You may not be right at the lowest point but I think a minor tweek is allowed (no more than 1/4 turn).

When I setup a set the normal deal is to have a meter on the horz out tube cathode, a meter on the shunt tube, and the HV meter on the CRT anode.

adj the eff coil for lowest setting, set HV to 23-24kv, check shunt current, as long as there is some current flowing in the shunt with a full bright raster, then you should be ok (and the HV should hold steady at 23-24lv) If you have no current flowing in the shunt then you can reduce the HV to 22kv see if that does it. then try 20kv if still nothing then you can tweek the eff coil. It drives the fly a bit harder so you dont want to go overboard.

all of the above assumes there are no other issues. I would think a weak tube in the HV section would be the 1st place to check.



again your are trying for some flow of current in the shunt with a full bright raster, that shows you have some reserve HV and the regulation via the shunt should hold the HV steady.


I would also try another horz output tube/damper/hv rectifier. If the emissions are low on any of these HV performance will suffer.

i have tried several rec tubes, reg tubes , horiz tubes, and damper tubes nothing ever changed and i had checked the cathode current and with scene changes the cathode current would jump over 220ma so i had lowered it to a steady 200ma but i had raised it and lowered it with nothing ever changing for the better.

ok so you are seeing .5ma to 1.5ma depending on raster brightness? of so then shunt is working.

HV holds steady thru those changes (raster brightness)? if the shunt is working then this should be steady.


if the above is correct then maybe there is something wrong with the video output that is causing a bias issue at the CRT, the video output during normal siganals (not raster). Is this what is happening?

Not really.
If the regulator is not working then yes the picture will bounce with scene changes.
There is another problem though if the thing loads down, blooms, blurs out and the 3A3 filament dies.
Ok maybe I am talking out my ass, ignore me

the hv does not hold steady it will go from 24kv to 23kv so this is not steady. this is where the hv pot is at , max 24kv and if i lower it to 20kv it drops more with scene changes and tweaking the eff coil did nothing if anything i maybe got alittle as the hv probe needle moved up a speck when i lowered the ma to 190ma. i am about ready to air a nasty video of a silvertone in its last days,lol.

Not really.
If the regulator is not working then yes the picture will bounce with scene changes.
There is another problem though if the thing loads down, blooms, blurs out and the 3A3 filament dies.
Ok maybe I am talking out my ass, ignore me

your right dan this is whats happening rec tube filiment dims blurrs, blooms, ect.:sigh:

you are worried about a 1kv change? that's it? a total of 1kv? from dark to light? are you serious?

How about C96 and C97? I have seen those go bad, they usually short.

A few kv or swing is not a problem and is normal.

When does it bloom?

no im not bothered by that but scene changes the hv drops from 24kv depending on the scene like white or others it will drop to 19kv. so its not regulating or something is dragging the hv down for whatever reason.

if those 2 caps are off the lin pot then no they were not changed.

no im not bothered by that but scene changes the hv drops from 24kv depending on the scene like white or others it will drop to 19kv. so its not regulating or something is dragging the hv down for whatever reason.

I was talking to davewm and we agree if you are able to get the 1.5ma off the shunt, the hv is working ok.
Sounds like something is loading it down, overdriving the crt.

So if you get a commercial or something thats all white with text then the picture blows out and blooms??

no it actually dont bloom from that its only bwhen i wanted to raise the crt bias to brighten it up alittle thats when it blooms and when white scenes are present the picture goes alittle dark because theres not enough hv it seems. if i leave the bias ccw i dont bloom but different colors make it dark and i confermed this by watching the hv probe on different scenes bias down.

Maybe it had an esl dump.
Did you do the setup the way it says in sams under greyscale? Does that end up with the bias to high?
If you have a really strong crt the bias will be all the way down. You really only want to advance the bias once one of the screens is maxed out.

Maybe it had an esl dump.
Did you do the setup the way it says in sams under greyscale? Does that end up with the bias to high?
If you have a really strong crt the bias will be all the way down. You really only want to advance the bias once one of the screens is maxed out.

did the grey scale so many times now and it improves nothing. the thing with the drives,rgb i cannot get the rgb lines across the screen unless i raise the bias alittle then i put the service switch back to normal and then i have to lower the bias because its all bloomed. this is the only way to see the color line in the setup, nothing in the sams about bias at least that i remember. the strange thing is i can leave the rgb drives ccw and still have good color.

If that jumper is missing, put it back as soon as possible to restore the regulation. If your HV goes too high, the CRT neck may shear off. :eek:

if that jumper is missing, put it back as soon as possible to restore the regulation. If your hv goes too high, the crt neck may shear off. :eek:

its back....

If that jumper is missing, put it back as soon as possible to restore the regulation. If your HV goes too high, the CRT neck may shear off.

HAHAHA its not a 70s Zenith, its a silvertone roundie that can hardly produce 24kv when hit by lightning.


did the grey scale so many times now and it improves nothing. the thing with the drives,rgb i cannot get the rgb lines across the screen unless i raise the bias alittle then i put the service switch back to normal and then i have to lower the bias because its all bloomed. this is the only way to see the color line in the setup, nothing in the sams about bias at least that i remember. the strange thing is i can leave the rgb drives ccw and still have good color.

Check the video output and voltages on the crt. I have a feeling something is being overdriven.

:tears::tears:maybe its time to just put it together and watch it the way it is rather then drive everyone including myself nuts. its been like this from day one and was told by don lindsly that something is loading it down and we were not able to figure it out yet. anyone want to buy a 63 silvertone,

the voltages were very close at the crt when i checked it yesterday. in a previous post i wrote what they were. i think page 3. sorry its on page 2.

try a new video out. a weak video out will result in a darker than normal pic.

try a new video out. a weak video out will result in a darker than normal pic.

did that already:drool: to.

Did you try more than one video out? did it make any difference at all (always does on mine, every tube has a different gain, every tube resulted in a different level of brightness, some a lot some not much but there WAS a change.

since you seem to have issues going from normal to setup did you check ALL the parts in and around the setup service switch. Are you adjusting to a just visable line? does the sams say anything about where the brightness control should be set (matters on some sets).

does the contrast control work as is should? where is it set at? Many times the contrast is set too high.

contrast control works fine, its at half. the problem here is hv not regulating and that it does seem that the hv is being loaded down. another video out tube i dont think will help but change little. the color lines i adjust to see then back off til just gone. and no i didnt check anything around the service switch. i think the sams did say something as to where the controls should be and i did what it said.

Why do you say its not regulating, I thought you said the shunt current changed with the brightness and was between .5 and 1.5 with a dark to bright raster and the HV held to 23-24kv all signs that HV regulation is working as it should.

Now you may indeed have a over load that exceeds the ability of the HV to supply current at excessive beam current in the CRT, but this is unrelated to HV regulation. The shunt can only regulate within a beam current operating range, go beyond that and its NOT a regulation problem, rather its a load problem, You keep saying it like those can't be separated. you could confirm this by observing the shunt current when the blooming happens, the current should drop to 0 as the KV drops to 19kv. this would indicate the regulation is working as designed and you are simply overloading.

My guess is you are simply over driving the CRT to make up for a brightness deficiency real or imagined. there could be an issue with the service switch that may be making the setup not work properly, but that can be worked around, not all set had setup switches you just do it by eye with a live signal.

I am sure you will suddenly have the solution and it will all be fine.

[QUOTE=ctc17;3052349]HAHAHA its not a 70s Zenith, its a silvertone roundie that can hardly produce 24kv when hit by lightning.




I always thought that any color CRT installed in any make or vintage of TV (not just 1970s Zenith sets) could have its neck sheared off from excessive high voltage. Were Zenith TVs the only ones to have this problem under HV runaway conditions? :scratch2:

If there is no regulation of the second anode voltage on the CRT, the voltage will go sky high, of course, until one of two things happens: the flyback burns out or the neck shears off the tube. Another problem when the 2nd anode voltage runs wild is excessive X-ray emission from the front of the tube and elsewhere. This is why all CRT televisions, from about the mid-'70s until the end of the CRT TV era, were equipped by Federal law with HV shutdown systems that would either make the picture unwatchable (by throwing the horizontal oscillator far off frequency, so far that no amount of fiddling with the hold control would bring the picture back into sync) or by blanking the raster entirely.

More myths!

i believe X-Rays go nuts over 25kv, the crt may internally arc and crack at 30-40kv. Most all of the tube sets have a hard time producing 25kv with the crt and regulator disconnected.
The 70s solid sets with tripplers could go nuts but not the tube stuff.

Sounds like a bad brightness control (or that bias pot you mentioned) to me, the blooming is caused by excessive current draw so if the screen brightness is all over the map that's where I'd start.

did you ever check out the above? may account for the touchy pots

the brightness pot seems to be ok but turn it all the way down and can still see just alittle movement in the picture thats on the screen. its all crazy to me in that why does it take the hv adjust pot to be maxed to get 24kv. but what is overall overdriving or overloading this crt to cause this indirect hv thing. clearly the hv pot should not be maxed to get 24kv my other sets are alittle over the half mark at 24kv. the voltages at the crt i would think are somewhat ok since they are not reading off the charts, the readings i got are on page 2. the hvwill hold at 24kv providing there are no white scenes because the hv does drop so if its regulating the thing is now to figure out what is loading down.

I would unplug the crt socket and the hv reg tube and see how high the voltage goes, then I would disconnect the hv from the crt and measure it in an attempt to verify there isnt something like a tad of air causing overloading.

But thats me, I have no fear of getting shocked or it arcing all over the place.

You changed the 3A3 right? Premium cigar rash?

Its common to fluctuate from 20-24kv, thats common and shouldnt be noticed.

Also, keep in mind how demanding modern content is on an old set. During the ntsc days they had all kinds of tricks to limit contrast and brightness. Subjects never work solid black suits on a bright white background. Thats why old programming looks washed out, that was intentional.
A strong crt+modern programming demands a perfect working chassis.

Good to use your hands, run it for 30 minutes, is the flyback hot? is the focus coil hot? the lin coil? etc

Sometimes just using a set that has been stored for years fixes alot of issues. Maybe its time to just use it gently for awhile and see if it wakes up.

I would unplug the crt socket and the hv reg tube and see how high the voltage goes, then I would disconnect the hv from the crt and measure it in an attempt to verify there isnt something like a tad of air causing overloading.

But thats me, I have no fear of getting shocked or it arcing all over the place.

You changed the 3A3 right? Premium cigar rash?

Its common to fluctuate from 20-24kv, thats common and shouldnt be noticed.

Also, keep in mind how demanding modern content is on an old set. During the ntsc days they had all kinds of tricks to limit contrast and brightness. Subjects never work solid black suits on a bright white background. Thats why old programming looks washed out, that was intentional.
A strong crt+modern programming demands a perfect working chassis.

Good to use your hands, run it for 30 minutes, is the flyback hot? is the focus coil hot? the lin coil? etc

Sometimes just using a set that has been stored for years fixes alot of issues. Maybe its time to just use it gently for awhile and see if it wakes up.back when i was troublshooting with don lindsly i pulled the crt plug off and the hv came up and he had said something was loading the hv down. the flyback never gets warm and the focus coil is bearly warm and i had even checked the ohms of the focus coil and it matched the sams give or take an ohm or 2.i also had tried several 3a3 including a solid state one. i do remember pulling the reg tube cap and the hv went up alittle over 30kv and taking the anode off the crt didnt make a difference only pulling the crt neck plug made a difference but soon as putting the crt neck plug back the hv dropped. a small amount of air would do this?????

An heres an observation....

I rewaxed a flyback out of one of these color sets. I boiled out moisture for over 90 minutes in a pot of wax that was 300F.
They are basically 90% paper and paper is hygroscopic and there has to be leakage through the paper at 24kv.
That very well could be your mystery load.

Speaking of hygroscopic, arnt yall about to get nailed by 3 record storms? Souldnt you be prepping for that and not worried about tvs? Making sure the car is full of gas, you have plenty of food, water, batteries a good working battery radio etc???

An heres an observation....

I rewaxed a flyback out of one of these color sets. I boiled out moisture for over 90 minutes in a pot of wax that was 300F.
They are basically 90% paper and paper is hygroscopic and there has to be leakage through the paper at 24kv.
That very well could be your mystery load.

Speaking of hygroscopic, arnt yall about to get nailed by 3 record storms? Souldnt you be prepping for that and not worried about tvs? Making sure the car is full of gas, you have plenty of food, water, batteries a good working battery radio etc???

well the flyback in the set was replaced and its a thordarson fly273 and its silicone potted and no arcing . so alittle air in this crt could have this affect afterall its the original that has silvertone on the neck plug. and the storm ahhh we will see if that happens even after the million dollar satillites they still cant get the weather right.

and the storm ahhh we will see if that happens even after the million dollar satillites they still cant get the weather right.

I wouldnt get caught with my pants down when you have a clear heads up.

I would be home watching the masses in total panic mode raid the stores of everything on my roundie totally prepared:smoke:

Ok we can rule out the flyback...hmmm

You can try putting your crt tester on it in cutoff test mode, crank the cutoff voltage all they way up and see if you get blue glow in the neck. That would indicate gas/air.
The only sure way is to substitute

oh did i tell you i got a brand new fly273 on ebay for 10.00. he had 10 flys for sale and i messaged him if he had another fly273 he said no but he said outbid everyone then pay the full amout and ill get the fly and a refund for the difference and he would put the other flys back on ebay. it worked out great got the refund and the fly273.

Everyone trips so hard on flybacks. I have never had one go bad on me, not even on the 16 I ran in a museum for 4 months the flyback held up. I have run across a few bad ones in old sets, maybe 2 in 100 sets. Not bad odds

Everyone trips so hard on flybacks. I have never had one go bad on me, not even on the 16 I ran in a museum for 4 months the flyback held up. I have run across a few bad ones in old sets, maybe 2 in 100 sets. Not bad odds

well some people have your luck but mine is if not for bad luck i would not have any luck at all, all my flybacks would have probably gone bad if i didnt have a spare or 2 for each set including the 47 fada.

Hey Timmy do not feel bad I have the same luck sometimes I had only one bad fly and that was on a ctc 15 roundy but I sold that set years ago my bad luck is with crts I have a ctc16 that needs a new jug cause mine got broken during transport it brought tears to my eyes.. Timothy

Maybe when the stores run out of flybacks in the next few days from the panic buying you will be able to sell them for a few thousand each...?

Maybe when the stores run out of flybacks in the next few days from the panic buying you will be able to sell them for a few thousand each...?

l m a o :banana::yes::D

Well...OK. That was more one of my off the wall sarcastic comments on priority, but hey, OK then

ROTFLMAO :banana::D:yes::banana::banana::D:yes::thmbsp:

well later today i will be checking the crt with the bk440 crt tester on the cutoff mode and raise it up full and hope i dont get the blue glow. with the set on and working i didnt see any purple glow or anything glowing just the filiments but maybe this test will put this thread to rest on this set, if i get the blue glow. i do remember pulling the 6bk4 cap off and checking hv and it was around 24kv but when i pulled the crt plug off the hv went out the roof at over 30kv, and this was with the 6bk4 cap still off so either something in the circuit is holding back the hv or it may be the crt, who knows.

That does sound suspicious.
I have suspected that the roundie crts that have the copper pinchoff nipple leak. If you can clean the neck off and use a flashlight to look back at the pinchoff nipple and see if its glass or copper that would be interesting.

I would be interested in knowing what the symptoms of different amounts of air contamination are.
What happens if the crt looses 1-2hg vs 10hg, at what point do the filaments burn up...
Maybe miniman82 would know??

That does sound suspicious.
I have suspected that the roundie crts that have the copper pinchoff nipple leak. If you can clean the neck off and use a flashlight to look back at the pinchoff nipple and see if its glass or copper that would be interesting.

I would be interested in knowing what the symptoms of different amounts of air contamination are.
What happens if the crt looses 1-2hg vs 10hg, at what point do the filaments burn up...
Maybe miniman82 would know??

I would think any amount of air in the tube would cause the heaters to burn out very quickly. Witness how fast an incandescent light bulb burns out if it is broken while under power.

That does sound suspicious.
I have suspected that the roundie crts that have the copper pinchoff nipple leak. If you can clean the neck off and use a flashlight to look back at the pinchoff nipple and see if its glass or copper that would be interesting.

I would be interested in knowing what the symptoms of different amounts of air contamination are.
What happens if the crt looses 1-2hg vs 10hg, at what point do the filaments burn up...
Maybe miniman82 would know??

you know its funny i was thinking of the video you posted awhile ago about the crt that had the brass nipple on the end. what a dumb idea for holding back that much vacuum. and you seemed pissed at that finding.

there was something said somewhere in this site posted that the filiments wont glow in air but i dont remember what the explanation was about it.

A very tiny amount of air will make the tune unusable. The ability to make an image is destroyed long before the filaments are.

When I was restoring my 1965 Zenith roundie the CRT was gassy but I did not know it at first. On my crt tester the tube showed good emission, etc. I restored the chassis and got 25 kV on the bench at the anode connector. I assemble the set, power it up and get no hv and purple glow in the crt neck. There was no picture and the crt filaments did not burn out. After I had the tube rebuilt, changing nothing else, I had a great picture with proper hv. It sounds like you might have a slightly gassy crt. Don't give up on it. These round tube color sets perform great even if they are a little maintenance intensive.

well i did the high cutoff test for a blue glow and nothing not even the purple glow so im thinking the crt is ok. but i now remember when i got this set and finished recapping and powered up the horiz hold control would not work because the control didnt have enogh room to work so i had to tweak the oscillator a touch to get the control to work. but now after all that is the horiz oscillator and i did find the sweep setup instructions for the hv and i will have to go ahead and do it and maybe this is the problem. someone at some point must have touched that coil and who knows how far it was turned. i dont know if the horiz hold is ok that it means the frequency is ok because this could be a drive to the fly problem maybe due to someone turning that slug. this will be fun for me as i never had to do this befor but it is a learning thing always with these sets.

ok the hv sweep set up did nothing so now i took voltaqes off the video output tube pin7 is to be 230 v but i only get 152 v pin 8 140 v but i get 133 v and pins 3-9 is supposed to be 5v but im getting -0v so i am really lost here and i did try another video out tube. i also check the 6fq7 horiz oscillator tube voltages, pin 1 is 20v right on, pin 2 -.1v i get -.238 v and pin 6 245v i get 248v.

What is pin one of the video out tube? Does adjusting the contrast change these numbers?
Are you using no signal?

The brightness and contrast control will move those voltage a bit.
Maybe C3 is shorted, leaky or in backwards?
Maybe theres something up with C40 and the blanking isnt working right? or the resistors in that area....

Im sure you replaced C3 (250uf) just because its new doesnt mean its good.

well i really think im just going to leave this set alone because im making myself crazy and others. everything i looked at did not seem all bad and the crt thankfully is ok unless there could be gas in it and not show with a glow of any kind. its amazing it has a great picture my only problem with it is that a white pic is not so white, white scenes has kind of a reddish tint to it and at the same time the white shows the hv drops. so if this is all that bothers me then maybe ill live with it. small white scenes are fine just the ones that take almost the whole screen has the reddish tint and no matter what i adjust it is what it will be because the hv cant keep up or there just is not enough for whatever reason. i tried again today 24kv at crt 6bk4 cap off then with cap off i pulled the crt plug off and i get what looks to me is 32kv. why the crt plug in it wont go over 24kv this is the question. i did change c3 and im sure if it were backwards it would have vented or other things may be worse off then they are. again if the crt bias is raised even alittle bit then the screen should not bloom the way it does. so this to me is a weird mystery that maybe ill solve one day.

Look at where that cap is in the circuit, it goes from the contrast wiper to ground. If it was shorted it would cause biasing issues with the video out.

Yea take a break, you can come back to it later and will be freshend up. If I spend too much time on one tv my eyes start to blur out then I know its time for a few days off.

Look at where that cap is in the circuit, it goes from the contrast wiper to ground. If it was shorted it would cause biasing issues with the video out.

Yea take a break, you can come back to it later and will be freshend up. If I spend too much time on one tv my eyes start to blur out then I know its time for a few days off.

well if that cap were shorted then the contrast control would not work or work well? because it works very good.

well if that cap were shorted then the contrast control would not work or work well? because it works very good.

If it was shorted it would work very well but it would shift the dc bias on the tube. Why not just check it?

is this cap right at the contrast control? a disc? ok that cap is electrolytic and its under the chassis. sorry for the brain fart it must be the storm coming.....

im looking at the schematic and that cap was a problem c3d says 250uf @50v but the can said 50uf@50v and c3c says100uf but it was 20uf on the can so sams was mistaken as always there were alot of mistakes. so i put in what was on the cans.

I hope you got your **** in order, everyone in that area, I know bryan and you, maybe a few others. Yall were lucky enough to get warning and get what you need.
I have never had to deal with something like this where you have warning. We have earthquakes that for the most part hit without warning, and we are due.

Ok, forget all that, cnn is on and the propaganda is melting my brain.

The values of that really dont make a big deal. You said the plate voltage was low and that would indicate a bias issue.

well dan how about i do this, what if i take the wire off the wiper pin of the contrast contol and check the cap that way ? this way i wont have to remove the chassis.

Hey, I have been following this thread and one thing seems to jump out at me. If the HV regulation is bad under load, what is the shape of the HV rectifier? Have you changed it? Is the filament lighting properly?

From what I have gathered on the thread, a big clue is the 32kv when the CRT is disconnected and the regulator cap removed. Putting on the regulator cap brings it down to 24kv with minimal loading by the regulator itself.

It is looking to me simply that the HV rectifier itself or associated circuitry (filament dropper resistor) is bad. But I think the key is the rectifier: if you have swapped it I'd try swapping again!

Hey, I have been following this thread and one thing seems to jump out at me. If the HV regulation is bad under load, what is the shape of the HV rectifier? Have you changed it? Is the filament lighting properly?

From what I have gathered on the thread, a big clue is the 32kv when the CRT is disconnected and the regulator cap removed. Putting on the regulator cap brings it down to 24kv with minimal loading by the regulator itself.

It is looking to me simply that the HV rectifier itself or associated circuitry (filament dropper resistor) is bad. But I think the key is the rectifier: if you have swapped it I'd try swapping again! i have tried several rectifier tubes including a solid state tube. the filiment does light so its no that and there is no filiment resistor.

Sense he's able to get 1.5ma at the shunt cathode that rules out a HV issue. Something is overloading it. Gassy crt or bias issue

1.5ma?

If that is true, I agree it's a gassy crt or a bias issue.

how about the hot voltages which were 140v was right on but the other is -55.9V but the sams shows -50v so i really dont know if this could mean a bias issue. and with the set playing i get no color glows in the neck nor do i get anything with the crt tester in the cutoff mode as far as a blue glow, so im really lost and out there at this point.

1.5 ma and correct cathode current would indicate the hv is working ok. correct screen voltage is another really good indicator the hv is working right.

1.5 ma and correct cathode current would indicate the hv is working ok. correct screen voltage is another really good indicator the hv is working right.

but the voltages at the 12by7a are not right.

The problem is the brightness control has way to much range and is over driving the video out.
Check r62 r64 and verify the brightness pot is not open

:Dok well i will close this thread by saying i am done with this silvertone as i just lowered the brightness readjusted the rgb drives and no more blooming with the bias up alittle to account for the weakest gun,RED and the whites are white now and no hv drop with whites. so i checked the brightness control pot and its right on at 250k and r62 and r64 both good as well as other resistors around the video output tube so in finding nothing else wrong here all i really did was lower the bright a touch so if this is what it took to improve what was wrong here well then i am going to leave it and take advantage of the fact that these sets had 10-20 or maybe 30% built in so if i am using a 10% leeway here well thats why they had this high of percentage, for errors because these sets were far from perfect so im happy with it now. well what more can i say,lol,lol...

My guess is you are simply over driving the CRT to make up for a brightness deficiency real or imagined. there could be an issue with the service switch that may be making the setup not work properly, but that can be worked around, not all set had setup switches you just do it by eye with a live signal.

I am sure you will suddenly have the solution and it will all be fine.

See above. from page 5 some 40 post ago.

Talked to CTC-17 says he talked to you about too much brightness range, seems like something that could be figured out if you stick with that.

Remember also that these old sets will never be as bright as a modern one, I find that people overadvance the brightness control on a regular basis then wonder why the picture blows out. A weak tube will make things worse, so if you don't plan to get a new CRT I'd live with the reduced brightness.

See above. from page 5 some 40 post ago.

Talked to CTC-17 says he talked to you about too much brightness range, seems like something that could be figured out if you stick with that.

yes it does seem now that the brightness control is driving alittle harder then it should and yes i can leave the bright reduced alittle but as ctc17 said when the sets were made no one would have wanted a new tv set that had to have the brightness lowered to fix other things. i would have thought the control was bad but it was not and the resistors as well are good. its not me overdriving anything to try to get a brighter picture, brightness was not the issue, hv and white colors and crt bias was so all these things are affected.:smoke: so ill leave it for now but i will keep this brightness issue on the back burner should anything related to that crop up.:smoke:

check the voltage at the plate of the 12BY7 with the service switch set to service.

check the voltage at the plate of the 12BY7 with the service switch set to service. ok, when i get a chance to get the back off again ill look in to that voltage at the plate. would you know off hand which pin is the plate otherwise ill look it up ?

Pin 7. What you are checking for is to see if the plate voltage drops to zero when in the service mode. I was doing some reading on RCA's and if this set has the same video out circuit, then it may have the same issue. If the 5.6k power resistor opens up (its on the service switch) you will lose plate voltage to the video out tube while in the service mode. The symptoms of an open resistor is very critical brightness setting.

ok, sounds like a possibility and i will get to it but i am certain in the beginning i went nuts checking everything and i do remember that resistor, its red and im sure i checked that one also. thats something like a 3-5 watt resistor. thanks davewm for that info, ill get on it. i just took a look at the schematic and there is 2- 5600 ohm resistors and a 2700 ohm so ill just chect them all as they are power resistors.

I am not sure you can test it in the circuit, so the best way to check is the voltage test at pin 7.