It's not uncommon if a set was in a living room close to a kitchen or if there is a coil or transformer containing wax close to a part for it to get an oily or waxy look. One check you could make if you don't have a leakage tester is to put a cap of over 10X the value in series with the low voltage end of the ceramic caps ( a .1uF will work for anything smaller than a .01uF) then measure the DC voltage of the point between the two caps. The voltage may initially float up but it should 0 out within around 10 seconds of connecting the DMM...If DC voltage doesn't 0 out within a reasonable amount of time you have leakage.

Putting a large test capacitance in series with a small test capacitance will yield an effective series capacitance close to that of the smaller capacitance, and the greater the difference between the two the closer the effective value comes to being unchanged from the existing small value.

AGC does need manual bias voltage injection if the automatic part is disabled....Heck if the automatic part is not disabled, but isn't working right using a manual bias supply to force it to the value it needs to be can be used as a troubleshooting procedure...The exact voltage it needs to work may be different than the one listed in the alignment procedure as the signal level may be different and the alignment procedure may desire adjusting amps at min or max AGC gain for linearity reasons.

I would strongly advise against changing capacitors unless you can prove failure. Changing caps WILL make alignment needed if they were not defective before replacement.
Changing resistors to 5% or better modern replacements typically fixes alignment issues if the original was bad, or barely changes anything if the original was good (provided lead dress is carefully kept the same).
I have on 2 CTC-2 and 2 CTC-4 sets fixed egregious alignment issues by replacing all resistors that were off tolerance or at the edge of tolerance with modern tighter tolerance parts....On the CTC-4s the sound, luminance and chroma were all so far apart from each other on the fine tuning that you could only get 1.5 out of 3 in good at once (you could get any 1 of the 3 in alone good at a different fine tuning spot) before resistor changes, and normal fine tuning and operation after resistor changes.

That’s the kicker here I haven’t found any bad resistors anywhere I had sound but it fizzled out to static and distortion can here voices but it was there almost to say a resistor went really high but found nothing that’s why I’m now looking at caps leaking or shorted.

But, as mentioned before, that is only what your meter is telling you with the set not in operation, things MAY change when power is on with the older carbon ones.

By carefully replacing them with 2% film types, you take that out of the equation, many have said before, disc caps are the most reliable types of caps used, and pretty much never fail unless physically damaged, and as EM stated, replacing them in this situation raises the chances of needing a full alignment to 100%

Trying something different on the bench got speaker hooked up and while I monitor the voltage on pin 8 of the first IF and at the same time using the subber when I probe at the 8.2pf no change in voltage but when I go ahead of that cap and the coils that the antenna goes threw I probe pin 2 of the same tube and the voltage goes from 64 to 70v for all I know maybe lightening hit this set and maybe damaged the coil or the 8.2 pf cap.

AGC will react to any kind of input to the grid of the 1st IF amp, be it a clean RF source, or noisy garbage and alter tube bias on pin 8, you so much at get a finger near C10 , let alone touch the leads, on the input side, ACG will change the bias of the tube.

Ok the 680k in k1 I subbed and the voltages went up from the 60s to 90 on first and 85 on second so you did say k1 were in common with the first 2 IF tubes. The 680k measured 744k not so high but this may be critical.

I also got the sound back nice and clear I will never take for granted that a tube is good because the tester says so it was the detector tube tests great but was no good and the voltages are 90 85 195 and I figure the voltages should come up alittle more once it’s back in and the tuner is plugged in. I hope this time I have video.

I’m going to make a new couplet k1 and being it has to do with the IF is it essential to pot it in some sort of epoxy or just on a small board.

Now I’m showing excessive currant on the -45v side of the hot. I think this flyback is crap got a dim screen.

this makes no sense... is was OK before, your last post stated " make a new couplet k1" was that done?

if so, it clearly upset something, try putting it back the way it was before.

No I didn’t make the couplet until I get resistors I only had the 680k the others are so so but in trying to set the -45 I noticed I can’t get it to -45 and the screen is dim at 22kv and with the meter on number 5 of the hot my meter is showing 1.3 amps on the ac scale but I had it set to dc but I know this meter if there is excess current it shows on the top scale and you are right none of this makes sense but I will tell you that I had to adjust the horizontal coil to get the oscillator going initially after getting a better signal to the IF but I took to look and the hot both turned red so I don’t know if I damaged the flyback because of that I don’t know and I’m preparing put the original flyback back in because I don’t trust the new one this maybe affecting the agc and the IF.

Or was the degradation of performance due to putting the chassis back in the cabinet/reconnecting everything? :scratch2:

jr

I really don't understand what you are trying to say, there is no “setting” of the -45v on the grid of the HOT, and that is not an absolute value by any means, it is a general voltage in DC, that means the horizontal oscillator is running.

There is no current measurement there.
DC voltage only.

The ONLY current measurement is cathode current, and this is done through a coupling cap AND a current meter for both tubes independently, but only when the set is up and stable.

The meter you have does NOT have the range to do the cathode current test, so don't try.
I'm not sure what you were attempting, but nothing but dc voltage measurements should be done on the grid of the HOT.

This tv is a huge cluster fxxk I tried 2 new hot no different and I tried a new 3at2 no different oh and now the 3 b+ voltages are low 275 is down 15 v 190 down to 185 and the 145 down to 138v this is nuts all I did was the 680k and that’s it.

I don’t know at this point if the hot both get red for to long if it would damage anything other then the 2 hot

I'm still quite confused by what you were doing here.
"trying to set the -45 I noticed I can’t get it to -45 "
what were you doing here?

what steps taken, what was adjusted , if anything?

How exactly is the meter connected to pin 5? Are you perhaps trying to use the AC-only clamp on jaws to measure DC?

jr

The horizontal oscillator/ hold coil I was able to adjust it to -45 with no problem because I found when it’s adjusted it’s one less thing I need to do but I know now that if the agc is trying to do what it does well then I waisted my time but now I’m stuck with a dim screen. And when it’s set to -45 the hv adjusts easily but now the hv won’t go over 22kv.

Ground and positive on pin 5 no clamp I think my meter was sensing ac from somewhere.

That is the wrong way to connect a current meter!:no:
Current is measured in series between the source and the load.
https://www.allaboutcircuits.com/tex...ammeter-usage/
Your meter as well as the circuit could be damaged by such mis-use.
jr

I know how to measure current I wasn’t measuring the current just the pin5 -45 to get the hv right.

So you weren’t trying to measure current?

But your meter did this: “with the meter on number 5 of the hot my meter is showing 1.3 amps on the ac scale” ? :scratch2:
Confusing!

jr

My dvm I think picked up stray ac or ripple other stuff I had worked on this has happened even when it’s on dc if it picks up any ac it will display it on the top ac scale dc is on the bottom.

That is not how horizontal is adjusted on the set, in fact -45v is not an adjustment at all, but as I indicated, an voltage that shows that the oscillator is running and does not have to be exact, the frequency, timing and waveform there is what matters, and this is set by horz hold and hoz afc.

The ONLY measurements in the area are at the cathode of the HOT, and you do not have the meters to do this, you would need 2 meters that can measure current up to ½ amp, and do both tubes at once, cutting pin 2 from ground and putting a .47 uf cap from pin 2 to ground on both, and then measuring the current across that cap 120ma, both, but since this set does not seem to have a horizontal efficiency coil to adjust, this is not needed on this set.

What ever mistake you did in this, you most likely cremated your damper tube, and it will need to be replaced, it is rather weak and easy to damage, much more easy to hurt than the outputs.

So are you saying that with the hot red plating cooks the damper tube. So if 770 boost is gone then the damper is gone.

Certainly possible. I have a Silvertone CTC-15 clone that would short it's damper and completely loose HV if the horizontal frequency went too far off...It blew at least 2 good tubes when I was working on it. That was the first color set I restored to working and it sat a few months with dead HV because until I borrowed the damper for another set I and discovered it had failed I didn't retest it because it tested good before I lost HV.
That same set later had a weak damper that would test great unless you held the test button down for like 30+ seconds to get it to slump. That weakness caused unusably low HV.
Some problems are spooky in that the failed component WON'T test bad unless subjected to conditions more extreme than the normal use case of the test equipment.

Well back on track I made the couplet and found out where ac was riding on dc a defective power supply cap no more ac.

Hi!

A few observations....
1. When the Horiz Output tube in Timmy's set gets red plates, it's most likely due to a
poor horiz drive to G1, from improperly working Horiz Osc. Remember the damper
rectifies the collapsing coil field and makes the current available for use in other circuits.
It may be a good idea to replace it anyway since it does a lot of work.....

2. Timmy states that he adjusts the -45V to the G1's of the Horiz Output Tubes. He does
this with the Horiz. Hold control. By adjusting the frequency the resulting bias on
the G1's of the Horiz Output tubes moves closer to normal. Is it a good thing? Who
knows. - but it should keep the output circuit safe. Best idea would be that when
he feeds a signal to the tv and it gets a picture that locks, after that leave it alone.

3. Yamama suggested that once the tv gets a picture and the HV is normal, PS Voltages
are normal, that Timmy leave it alone for hours and see how long it runs like that. -
I Like that idea a lot! You really need to determine what causes the two states that
this tv operates at, A) Semi-Working, and B) Low HV and Red Plate HV Output tubes...
What causes these 2 states? Is it taking the chassis out? Putting it in?
4. AGC, a normal tv will work without HV fluctuating with an overloaded signal, and
with no signal at all it gets snow, and in both conditions no glowing plates on the
horiz output tubes.....

One thing Timmy needs to do is measure the AGC line voltage when the tv is working
and when it's in its Overheating tube state and see if there is a difference. If so, then
you need to set up a battery that can force that line between the 2 levels and see
if the AGC is the ultimate cause of this TV taking 34 pages to track down this problem.

Could the AGC be causing IF circuit tubes to be drawing too much current? If you are
going to order a new damper tube, then order a Voltmeter with 10A Current scale
too, and get one that is NOT Auto-range, get one that you have to turn the dial to
read 10A, 2A, etc. I'll say it again with a 10A Scale, the resistor inside the meter
is actually a piece of wire with almost 0 ohms, and you will have almost 0 resistance
added to the circuit when you measure 500ma, or 1/2 Amps.


.

Not sure where we are now but.......
To measure H Out current you need to open the cathode pin from GND
and put a ampmeter in series with it. Depending on the meter you should
decouple the cathode with a cap to smooth it out. It goes in // with the
meter.
SAMS has instructions on value of cap & procedure.
Adjusting the H. osc ( hold) will effect the G-1 negative voltage.
Keep in mind the whole thing by design needs to be in resonance
to be happy. If the G-1 is in spec you are good till that point.
A freq counter or scope can show you if its at 15,750.

AGC as a rule goes to the RF amp & IF # 1 & 2.
SAMS will show AGC voltages either with or without a strong signal
or both ways. AGC problems are VERY rare, I cant really remember
many in 40 yrs & tens of thousands of sets.

73 Zeno:smoke:
LFOD !

As mentioned above, this set does not have a horizontal efficiency/linearity coil to adjust, so where the cathode current can be measured, there is no way to adjust it on this.

and yes AGC problems are rare, they do happen, bit in this case, it's more likely the IF alignment is messed up.

Tomorrow I’m going to check resistances on the 6hs8 according to sams. when I had this running the agc control on the rear turning both ways made no difference at all but the noise gate did I do get video but it is distorted but can see images so since making k1 will see what this does. There is a .4 v rf source to agc if that’s missing from the tuner I don’t know what the consequence is if that’s not there.

Checked resistances on 6hs8 they are all wrong even with the couplet I made up tried it anyway and it seemed to make it worse. I don’t know if the couplet all together would have to be potted I did incapsulated it in heavy heat shrink.

How far off were the resistances? Perhaps you could list the measurements by pin number, so we might be able to figure out what’s going on here.

I don’t think that the potting is important.

jr

My mistake I had to measure from x2 not x1 and it turns out they are all good. But the voltages are not right at all 6hs8 pins 6-145v 114 7-200 119 3-2.5 8.3 8-230 143 9-140 31 2- 275 1-190

Am I reading this right: “pin 9 140 volts expected, 31 volts measured” ?

jr

Yup

What is the input impedance of your dmm? Most dmms are 10 megohms, but some are only 1 megohm. SAMS specifies use of a VTVM (11 megohms) but a 10 megohm is usually good enough!

jr

It's very doubtful that his meter is 10m, because he has an electrician's (clamp) meter, and not a full function DVM, this has been brought up several times before by quite a few, including myself that he invest in a better one that has a dedicated 10a scale, and was made for the electronics field rather than an electrician, because it is very likely it's giving inaccurate readings in some cases.

He has this.
http://www.instrumart.com/assets/uei...nix-manual.pdf


Again, a better meter is suggested before believing any voltage readings, one that is known to be 10m, as the one on hand may be loading the circuit down.

Is it possible for a video detect diode to check good but be bad from leakage ? Has anyone ever seen this