Hi all,

Still having problems with this TV. I can't get horizontal lock when I feed a signal into it. I think the best thing to do is list what I've eliminated as possible causes. I am using the 5" CRT for testing and I have left the focus coil in place. It doesn't affect the image focus. All electrolytics and film caps have been replaced along with a couple of 270pf micas in the IF. Here's the list of what I've checked off as probably not causing the issue.

1.Signal Source. I've tried 2 signal generators, a live broadcast feed and I have fed an IF signal into the video IF in 2 places using the B&K 1077. No change in the absence of horizontal lock.
2. Tuner. As I said, I bypassed the tuner by injecting a signal directly into the IF.
3. 5" CRT. Not the cause. Same symptoms on 2 different 10BP4 CRTs.
4. Horizontal and vertical control pots. This is a concentric shaft pair. Each has been cleaned and each ohms out within specification. Just for good measure, I swapped out the control with one from a parts chassis that was cleaned and ohmed. No change in the symptoms.
5. Tubes. Every tube in the TV has been tested, replaced with NOS tubes, swapped out tubes from stock and other working TVs etc. All socket pins cleaned. No change.
6. Control pots on rear of chassis. All extensively cleaned (Horizontal and vertical position, focus, vertical linearity, height, horizontal drive) and tested for resistance. All within specs. Focus, horizontal drive pots swapped out with clean and evaluated pots from parts chassis. No change.
7. Sync Discriminator Transformer T-108. Ohmed and swapped with transformer from parts chassis. No change.
Contrast pot. Cleaned and resistance tested. Replaced with parts chassis pot. Replaced with new 10K pot rigged up separately. No change in symptoms.

So, I'm running out of ideas! I checked the signal from the horizontal oscillator at point A on T-108 and it is clean as a whistle...15.75K and a smooth sine wave. On pin 2 of the Horizontal Sync Discriminator 6AL5, it's a jumping mess of a signal that occasionally looks like an accurate waveform but it scrambles with the picture.

I've been concentrating the troubleshooting in the sync and horizontal circuits and any resistor >10% out of spec has been replaced. I even did some Shango troubleshooting by whacking a few things with the back of a screwdriver with no luck.

I know I've caused some frustration with some being a rookie who doesn't know enough about how these things work and sometimes has taken the experts through pages of messages only to find out the problem isn't in the TV but the signal generator or a bad tube. I apologize for that. I think I'm learning at least to eliminate the dumb stuff first before posting a situation that has me stumped. I'm also getting better at accurately following through with some of the suggestions that are given.

The deflection circuitry on most of these early RCAs is pretty much the same if not identical. My hope is there are some members experienced in these early RCA chassis to provide some insight.

Thanks everyone.

Chris

Listed in the SAMS is a rather detailed step by step procedure under horizontal osc adjustment / complete alignment, this sounds like what is needed as a slight retouch most likely won't work, I have not ever had to do this myself, but if it is way off, these steps may help if done as shown.

Also, the RCA service data may have more detailed steps on how to align this area.

Listed in the SAMS is a rather detailed step by step procedure under horizontal osc adjustment / complete alignment, this sounds like what is needed as a slight retouch most likely won't work, I have not ever had to do this myself, but if it is way off, these steps may help if done as shown.

Also, the RCA service data may have more detailed steps on how to align this area.

Yes I have the service data. I can give the alignment adjustment a try. At least it'll get me to the place where I can narrow down the issue but as persistent as this has been and as many by sight and feel adjustments I've done with the controls, drive and T-108 transformer...all of my improvisational efforts to get this zeroed in have all gotten to the same place...a picture that becomes somewhat locked for a second and is kinda clear and aligned to horizontal chaos.

OK well the first step in a complete realignment is "Tune in a station and adjust the fine tuning for best sound quality. Turn the T-108 frequency adjuster on the rear until the picture is synchronized." I've turned it through its full range slowly and there's no spot where the picture syncs. It gets as close as I've gotten it before, but never full sync.

“a picture that becomes somewhat locked for a second and is kinda clear and aligned to horizontal chaos”.

Under what conditions do/did you observe the “clear” picture?

jr

The only thing I can think of, is out of tol resistors in the sync area, especially near the 6AL5 phase det, when I restored my FADA 630TS clone, many resistors were replaced, if perhaps the 2 470k resistors and the 1m are a bit off, it might upset the horz phasing, I'm sure they were replaced with 1% new in my set, as well as most of the other resistors in the sync area that did not test within 10% what they should have.

The only thing I can think of, is out of tol resistors in the sync area, especially near the 6AL5 phase det, when I restored my FADA 630TS clone, many resistors were replaced, if perhaps the 2 470k resistors and the 1m are a bit off, it might upset the horz phasing, I'm sure they were replaced with 1% new in my set, as well as most of the other resistors in the sync area that did not test within 10% what they should have.

The two 470K and 1M resistors have been replaced with 1% resistors. All the resistors around the 6AL5, except for the 5K power resistor that tests spot on, have been replaced

“a picture that becomes somewhat locked for a second and is kinda clear and aligned to horizontal chaos”.

Under what conditions do/did you observe the “clear” picture?

jr

When I fiddle slightly with the horizontal hold or the discriminator frequency or the fine tuning or the brightness pot or the contrast pot or the horizontal drive pot... Let me say when I said clear and stable...I'm talking for less than a second. It seems to change from almost think I can pull it in to awful to worse than awful back to bad almost think I can pull it in etc. I wish I could post a video. It would explain it so much better.

How strong is the vertical lock? Is it just 5 degrees or something more healthy like 1/4 turn.

Sync issues can be caused by 2 things, sync separator issues, and sweep oscillator issues. If vertical lock is weak too it indicates that the sync separator is bad or marginal. And a marginal sync input won't help the horizontal if it too is marginal. Also it's good to consider every component after the H and V sync split part of the osc circuit it feeds and scrutinize those carefully too.

Also the 630 chassis family sets lack AGC so it is possible to have contrast (which in these sets is more accurately called a manual IF and tuner gain control) set so high that the sync pulse gets clipped off at the video detector from signal overload... that's another thing to watch out for that can mess up sync.

How strong is the vertical lock? Is it just 5 degrees or something more healthy like 1/4 turn.

Sync issues can be caused by 2 things, sync separator issues, and sweep oscillator issues. If vertical lock is weak too it indicates that the sync separator is bad or marginal. And a marginal sync input won't help the horizontal if it too is marginal. Also it's good to consider every component after the H and V sync split part of the osc circuit it feeds and scrutinize those carefully too.

Also the 630 chassis family sets lack AGC so it is possible to have contrast (which in these sets is more accurately called a manual IF and tuner gain control) set so high that the sync pulse gets clipped off at the video detector from signal overload... that's another thing to watch out for that can mess up sync.

Hi Tom...thanks for chiming in! Yes, vertical lock is stable but only compared to the horizontal. It is marginal at best and absolutely loses lock in less than a 1/4 turn. The 3 tubes in the sync circuit are NOS and I've swapped them out with multiple tubes from other TVs and from my stock with no change. I've changed only the resistors that were out of value more than 5% but I still changed 4 resistors. I was just going to change everything in the Sync circuit with 1% resistors. I've been aware of the contrast pot's influence on the signal and I've had it at conservative settings.

Exactly, on mine, I went through each and every resistor end to end, with a parameter of 10%, and any that tested out of that range was replaced, ones that were within got marked with a green ink pen, took me quite a long time to do it.

So you may still be having resistor issues.

One more thing...I don't know if it means anything and I don't know why it is what it is. One of the B+ voltage rails is low...the 135V line is at 95V only. Everything else is bang on. All new bleeder network and 2 brand new 5U4 rectifiers

I would fix the power supply first... could be the main problem.

jr

40 volts too low on that rail, could be an issue, as it does power the sync separator and 2nd sync amp, and other areas.
I had the same sort of problems, but I really doubt it is the same as you are seeing now, but what ever it is, that voltage needs to come up to around where it should be.

40 volts too low on that rail, could be an issue, as it does power the sync separator and 2nd sync amp, and other areas.
I had the same sort of problems, but I really doubt it is the same as you are seeing now, but what ever it is, that voltage needs to come up to around where it should be.

I do have additional low voltages. The 275v is 263v. 135v is 101v. -2.0v is -1.7v. -18v is -18.8 and the -100v is -81. What the hell is going on? I'm supposed to have 350v DC on pin 8 of the 5V4 reaction scanning tube and it reads 330v. Supposed to have 300v going into the filter choke and I've got 285v.

Here is the power system. The voltages written are what I've measured.

https://imagizer.imageshack.com/v2/1024x768q70/922/zYMbrH.jpg

First, don't take what is in the RCA service manual as absolute, the will be variations, I worked with that and the SAMS, and found that thing are sort of halfway between what is shown in both, don't look at what is listed in them an what voltages MUST BE, more sort as a guide.

And since ground is not AT ground in this set, but going through a bleeder network to produce negative voltages, any problem in one or more of them on the chain like the 135v line or more will tip everything out of balance and give weird voltages and odd results, like bandersen found out when he accidentally turned his focus coil into a battery by dunking it in Evapo-Rust.

something has upset the balance of your power system.
most likely in the 135v line.

Indeed! If the two resistors in the 135 volt divider are in spec, I would be checking all circuits connected to the 135 volt supply for high current draw.

jr

The 1360 ohm was replaced with a 1.5k 25W resistor. Closest I could get in that watt range. That wouldn’t account for the 30-35v loss in the 135v line would it?

That could be the problem, however, it does not rule out an issue with the 135v line.
It's unusual for the high power wire wound resistors to go bad, it does happen but it's rare, it is much more often for the candohm resistors to fail before the 25 watt ones, were yours really bad? And what were all the other bleeders replaced with?

However, since you already have the 1.5k 25 watt, what you might think about doing is getting a 12k 25 watt, and hook it in Parallel to the 1.5k, this will get you 1333.33, much more close to the original value. https://www.mouser.com/ProductDetail/Vishay-Dale/RH02512K00FE02?qs=sGAEpiMZZMvNd0dY0KymzmQf1OWfOWEv E0g4acOQrU8%3D

Yes ^^^ but you can use a much smaller wattage. The power will divide in the same ratio as the resistance.

A 12K rated for 3 watt or better will do. If you don't have one handy, use a 10K just to see what effect it has.

Here's how I did a 721TS recently. I paralleled a 1500 with 5000 to get the required 1125.
https://live.staticflickr.com/65535/53787836832_69a2bbdb4c_z.jpg (https://flic.kr/p/2pX3HX7)

The 1360 ohm was replaced with a 1.5k 25W resistor. Closest I could get in that watt range. That wouldn’t account for the 30-35v loss in the 135v line would it?

Not all of it...perhaps it would decrease the 135 volt line 10 to 15 volts. :scratch2:


jr

It should be interesting to see what the full output of the 5U4Gs are before going into the bleeder network, as in from pins 8 (cathode positive point ) to the -100v point (transformer center tap) , should be at least 400v, if not more reading at those points.

Yes ^^^ but you can use a much smaller wattage. The power will divide in the same ratio as the resistance.

A 12K rated for 3 watt or better will do. If you don't have one handy, use a 10K just to see what effect it has.

Here's how I did a 721TS recently. I paralleled a 1500 with 5000 to get the required 1125.
https://live.staticflickr.com/65535/53787836832_69a2bbdb4c_z.jpg (https://flic.kr/p/2pX3HX7)

How common is it for the larger 25w resistors to be bad? The tested OK on mine a few years ago, so I left them in. only 1 section candohm resistor tested funny at the time, which I bypassed, I should have done all 3 sections, as I now suspect the other 2 are starting to fail as well, as when the sound is at max,the picture shrinks horizontally. Granted this set had no sound OEM, but that sound not be an issue, as it has the same power system in it as TVs with sound originally.



For now, I have the audio output pulled and am using a cheap LM386 amp for sound till I address the candohm resistor issue, but, do I replace ALL the bleeder network preemptively, or leave the larger 25w resister in if it still seems good?

The candohms are not uncommon to find shorted to chassis or open, and the tubular ceramics do open sometimes (changed an open one on a 721TS this spring).

One small concern I have is your mention of bypassing a resistor section...If it wasn't an end section and it isn't open or more than 10x above its rated value it's hard to bypass it without the original throwing things off or extremely delicate surgery to force open the original.

Personally the B+ voltages are close enough that I wouldn't be chasing them as a cause of any other issue.

The candohms are not uncommon to find shorted to chassis or open, and the tubular ceramics do open sometimes (changed an open one on a 721TS this spring).

One small concern I have is your mention of bypassing a resistor section...If it wasn't an end section and it isn't open or more than 10x above its rated value it's hard to bypass it without the original throwing things off or extremely delicate surgery to force open the original.

Personally the B+ voltages are close enough that I wouldn't be chasing them as a cause of any other issue.

it was an end section of the candohm that tested rather high at the time and was bypassed, forget which end. :/
I should have done the whole thing. :sigh:

My set, the -100v tests at -86v and it changes when i adjust the focus, so I dont think your -81v is an issue.

http://suzaku.live-evil.org/0613242200a.mp4
Mine
it was the 6750 ohm part on mine that was replaced.

Thanks everybody for the discussion. Couldn’t work on the tv today “new hot tub delivery!!!!) but I’ll be back on it tomorrow. My hunch as I’ve said is this just doesn’t look like an issue caused by a low but stable voltage. It seems more like intermittent noise although it’s not the tuner. We’ll find it just like my RA-103 that was on and off my bench for a year until you guys led me to the problem.

Yes ^^^ but you can use a much smaller wattage. The power will divide in the same ratio as the resistance.

A 12K rated for 3 watt or better will do. If you don't have one handy, use a 10K just to see what effect it has.

Here's how I did a 721TS recently. I paralleled a 1500 with 5000 to get the required 1125.
https://live.staticflickr.com/65535/53787836832_69a2bbdb4c_z.jpg (https://flic.kr/p/2pX3HX7)

That takes me back...the 721 was my first serious restoration several years ago. I need to revisit that one. Ended up running composite video because I couldn't get picture and sound through the tuner and RF. But first RCA things first!

That could be the problem, however, it does not rule out an issue with the 135v line.
It's unusual for the high power wire wound resistors to go bad, it does happen but it's rare, it is much more often for the candohm resistors to fail before the 25 watt ones, were yours really bad? And what were all the other bleeders replaced with?

However, since you already have the 1.5k 25 watt, what you might think about doing is getting a 12k 25 watt, and hook it in Parallel to the 1.5k, this will get you 1333.33, much more close to the original value. https://www.mouser.com/ProductDetail/Vishay-Dale/RH02512K00FE02?qs=sGAEpiMZZMvNd0dY0KymzmQf1OWfOWEv E0g4acOQrU8%3D

The 1360 was replaced with a 1500, the 230 with a 240, 6750 with 6800 and the 93 with a 100 ohm.
I guess they're all high.

It should be interesting to see what the full output of the 5U4Gs are before going into the bleeder network, as in from pins 8 (cathode positive point ) to the -100v point (transformer center tap) , should be at least 400v, if not more reading at those points.

Service data says 300V DC at pin 8. I have 295V.

How common is it for the larger 25w resistors to be bad? The tested OK on mine a few years ago, so I left them in. only 1 section candohm resistor tested funny at the time, which I bypassed, I should have done all 3 sections, as I now suspect the other 2 are starting to fail as well, as when the sound is at max,the picture shrinks horizontally. Granted this set had no sound OEM, but that sound not be an issue, as it has the same power system in it as TVs with sound originally.



For now, I have the audio output pulled and am using a cheap LM386 amp for sound till I address the candohm resistor issue, but, do I replace ALL the bleeder network preemptively, or leave the larger 25w resister in if it still seems good?

I could put the big, enameled wire wound back in and see if it makes a difference. The Candohm had to go...not that it was bad but they're too unreliable.

Or I do have a 10K 7W I could parallel that would get me to 1300???

Or I do have a 10K 7W I could parallel that would get me to 1300???

Yes... 1304.

jr

On V124 (6AC7) horz osc. control tube, what voltages do you have on:

Pin 8 (plate) -- calls for 194 V
Pin 6 (G2 ----- calls for 105 V
Pin 5 (cathode)
Pin 4 (G1) ---- calls for 2 V negative

Cathode has 10 ohms to ground, so prob. not much there

I'll check those voltages later today. I've lamented my inability to show via a video what this TV is doing but if you check out shango66 today, he's working on a Packard Bell color set with AGC issues and that TV is doing the exact thing mine is doing. I know this TV does not have an AGC circuit but maybe that narrows the issue down to a specific location. Not sure.

On V124 (6AC7) horz osc. control tube, what voltages do you have on:

Pin 8 (plate) -- calls for 194 V
Pin 6 (G2 ----- calls for 105 V
Pin 5 (cathode)
Pin 4 (G1) ---- calls for 2 V negative

Cathode has 10 ohms to ground, so prob. not much there

Plate is 216 V
G2 is 86
G1 is -1.55
Cathode is...30 V DC?

30V on the cathode?!:saywhat::eek::yikes: What is the resistance-to-ground from the cathode? Print calls for 10 ohms (R194).

30V on the cathode?!:saywhat::eek::yikes: What is the resistance-to-ground from the cathode? Print calls for 10 ohms (R194).

11.5ohm on the resistor. 30V on pin5 Here
s the topic area...

https://imagizer.imageshack.com/v2/1024x768q70/922/mqEWTb.jpg

11.5Ω is close enough. The other end of that resistor ties to pin 2 which is ground. There should be solid continuity (zero ohms) from pin 2 to the chassis. Is there?

Yes

you may wanna think about replacing the 10ohm resistor anyway, that 30v on the cathode is really weird! :scratch2:

Is your volt meter auto range and perhaps indicating 30 mili-volts rather than 30 volts? :scratch2:

jr

No it’s 30 volts DC. Measured several times. My meter always puts a zero and a decimal and shows millivolts that way

But let’s hold off on wasting brain power on speculation until I can re re recheck it

30 volts across a 10 ohm resistor would be 90 watts...resistor would be getting very hot! :scratch2:

jr

When I measure it next, if I’m getting the same thing I’ll post some photos of the measurements and pins. That way if I’m doing something very stupid I won’t end up dragging u guys down any rabbit holes

It is 3 millivolts. Sorry and thanks for picking up on that. My bad. The “m” next to the “V” was microscopic!

I mean 30 mV

It is 3 millivolts. Sorry and thanks for picking up on that. My bad. The “m” next to the “V” was microscopic!

And they seem to get smaller every year!:D

jr

And they seem to get smaller every year!:D

jr

You're right about that!!! I paralleled the 1.5k with the 10k resistor to bring the resistance down to 1.3k. Same symptoms although the 135 volt line came up to 105V

Not sure where we go from here. The only thing I can find off is a lower than expected voltage. Can a resistor create a stable unstable condition? If I had not bypassed it by injecting an IF signal directly into the video IF, I would suspect the tuner but that can’t be it. I guess I need to start replacing resistors in the sync and horizontal circuits even if they test ok. At the least it will eliminate them as the culprit.

I think this one may go on the back burner for a while. I’m at a dead end with it. Sometimes it’s for the best to give an old chassis a rest and stop pokin and burnin it! Appreciate everyone’s advice and interest. I’ll be back with it in a bit.

Tryin to give it a rest but just a few more observations. I put the 10BP4 back in the chassis. The symptoms are the same but I noticed it’s less of an issue when the set is cooler. When it’s in sync it’s a beautiful picture and the resolution is very good. That’s why this irks me as much as it does. If I could just get the picture stable it would be a great performer. Once it heats up the problem becomes worse. I don’t know if that means anything or points towards a resistor issue. Trying to walk away but it’s tough. This TV came with it’s original stand so it’s a real find.

I feel your frustration bro. I might've missed it, but have you checked voltages on:

V118 (6SK7) 1st sync amp ----- pertinent voltages are pins 4, 6, 8 (that's G1,G2, plate)

V119 (6SH7) sync separator --- pertinent voltages are pins 4, 6, 8 (that's G1,G2, plate)

V120 (6SN7a) 2nd sync amp -- pertinent voltages are pins 1 & 2 (that's G1 and plate)

Are those tubes lighting up good? If any are metal, they should be getting warm after a few minutes running.

Temperature related suggests drifting components. Got a can of freeze spray or such handy?

Not handy but I'll get some

I feel your frustration bro. I might've missed it, but have you checked voltages on:

V118 (6SK7) 1st sync amp ----- pertinent voltages are pins 4, 6, 8 (that's G1,G2, plate)

V119 (6SH7) sync separator --- pertinent voltages are pins 4, 6, 8 (that's G1,G2, plate)

V120 (6SN7a) 2nd sync amp -- pertinent voltages are pins 1 & 2 (that's G1 and plate)

Are those tubes lighting up good? If any are metal, they should be getting warm after a few minutes running.

I'll check those tonight. Yes they are warm and NOS but I've tried several tubes from my stash and from the parts chassis with no change.

It might be worthwhile to check all power supply voltages cold vs hot. :scratch2:

jr

I'll check those tonight.

Cathode is ground on all 3 tubes, so wasn't included in voltage chart.

I feel your frustration bro. I might've missed it, but have you checked voltages on:

V118 (6SK7) 1st sync amp ----- pertinent voltages are pins 4, 6, 8 (that's G1,G2, plate)

V119 (6SH7) sync separator --- pertinent voltages are pins 4, 6, 8 (that's G1,G2, plate)

V120 (6SN7a) 2nd sync amp -- pertinent voltages are pins 1 & 2 (that's G1 and plate)

Are those tubes lighting up good? If any are metal, they should be getting warm after a few minutes running.

I really don't see a smoking gun here except for the lower voltages associated with the reduced 135V line being bled off to another voltage line source.

6SK7 #4 -3.6V #6 96V #8 187V
6SH7 #4 -4.3V #6 104V #8 103V
6SN7a #1 -1.3V #2 68V

A suggestion - from a dead-cold start, with your voltmeter on the 135V source (jct. of R185/R186), turn the set on. Since the 5U4s give full B+ almost instantly, is the 135V still low? Or is there a signifigant drop as the rest of the tubes begin conducting? This would tell you if it's tubes lugging the 135V down, or something else circuit-wise.

A suggestion - from a dead-cold start, with your voltmeter on the 135V source (jct. of R185/R186), turn the set on. Since the 5U4s give full B+ almost instantly, is the 135V still low? Or is there a signifigant drop as the rest of the tubes begin conducting? This would tell you if it's tubes lugging the 135V down, or something else circuit-wise.

Great suggestion. The diagnostic skills available here are an invaluable instruction. I don't know why trying that didn't occur to me...it should be a pretty revealing exercise but I guess that's part of the learning curve! I will take a look at that this evening and thank you so much for hanging in there with me.

Again, I'm not saying this is the same problem that your set has, but it's the one that MINE had, I too had a weird problem with the 135v rail being very low, it did not cause me any sync problems, but did cause tuning and contrast problems, the fault was eventually tracked to the WHITE HI-Q 1500pf caps on the IF power rail, the ones with the red ends, NOT the brown tube like ones, on mine, many of those red ends seemed to have degraded and gotten gummy, some of the caps looked like they leaked something even, after replacing only those white HI-Q 1500pf caps, my 135v rail then came up to nominal range, and things worked much better, not perfectly as my tuner is a bit weak, but much better then when I started.

Again, not saying that this is the problem you are having, but worth looking at.

The old style ceramic caps?

The old style ceramic caps?

yes, I posted pics of the ones that gave me problems on your other thread.

http://videokarma.org/showthread.php?t=276630&page=2

I'm wrapping one up right now and all five of the 270pF mica IF coupling caps were bad. Symptom was poor gain. That might account for your tuner being weak.

Never had trouble with the white Hi-Q caps but of course anything is possible.

https://live.staticflickr.com/65535/53804853270_20e45c6a24_z.jpg (https://flic.kr/p/2pYxWkY)

I'm wrapping one up right now and all five of the 270pF mica IF coupling caps were bad. Symptom was poor gain. That might account for your tuner being weak.

Never had trouble with the white Hi-Q caps but of course anything is possible.

https://live.staticflickr.com/65535/53804853270_20e45c6a24_z.jpg (https://flic.kr/p/2pYxWkY)

I just know that a third to a half of the ones in mine had rather soft like red ends, and a weird brown sap like stuff that seemed to be coming from them, I really did not get where it came from or how it got there, other that it must have come from the cap somehow.
I can post a pic of some before they were removed later.

And yes, the 270pF micas in mine are still OEM, and most likely need to be changed, but the tuner was in poor shape as well, but did work to some degree, looking inside, I could see insulation starting to come off of the wiring inside, I did try to clean contacts, but not too much, for fear of making it worse, the pair of 150 ohm resistors in the rf amp were quite out of tol when I tried to test them, how far , I don't recall.
This set, does not get snow with no input, but does get a picture (with some slight fuzz) with a normal rf modulator, and crystal clear when I BLAST it with a Blonder Tongue micm-d.
It can do with an alignment, as it's hard to get the sound and video to tune in at the same time, though I don't have sweep marker generator, I have the digital RF generator, which I used on the Arvin TV, which ironically is the only one of my older BW sets that gets snow with no input, meaning that they all could use a touch up.

http://suzaku.live-evil.org/0415202203(1).jpg

pic of the weird brown stuff on the white caps

A suggestion - from a dead-cold start, with your voltmeter on the 135V source (jct. of R185/R186), turn the set on. Since the 5U4s give full B+ almost instantly, is the 135V still low? Or is there a signifigant drop as the rest of the tubes begin conducting? This would tell you if it's tubes lugging the 135V down, or something else circuit-wise.

295V DC when first turned on and it held for 4-5 seconds and then took a steady dive down to 104V in the next minute.

I really don't see a smoking gun here except for the lower voltages associated with the reduced 135V line being bled off to another voltage line source.

6SK7 #4 -3.6V #6 96V #8 187V
6SH7 #4 -4.3V #6 104V #8 103V
6SN7a #1 -1.3V #2 68V

.

These voltages are I think pretty far off.... How are the resistors R160, 161, 157, 228, 153, 156, 157....
I'm wondering about the -18, -2, and -100 v sources, as it looks like they are providing bias for all
the little tubies that are also using the 135V & other sources... Higher G1 voltages will
mean all the tubies conduct just a little bit more for each one.... and you know
what that means.... More Ampies being used.... and if the 3 tubies you
provided G1 voltages for, they are each a little higher..... More
ampies means B+'s all go down..... Good suggestion about
monitoring the 135V as the set warms up, I suspect it will
go down as the set gets going, no surprise there...

.

http://suzaku.live-evil.org/0415202203(1).jpg

pic of the weird brown stuff on the white caps

I don't have those caps in my TV...it has the resistor-like caps all of them in the 6.3V filaments to ground.

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These voltages are I think pretty far off.... How are the resistors R160, 161, 157, 228, 153, 156, 157....
I'm wondering about the -18, -2, and -100 v sources, as it looks like they are providing bias for all
the little tubies that are also using the 135V & other sources... Higher G1 voltages will
mean all the tubies conduct just a little bit more for each one.... and you know
what that means.... More Ampies being used.... and if the 3 tubies you
provided G1 voltages for, they are each a little higher..... More
ampies means B+'s all go down..... Good suggestion about
monitoring the 135V as the set warms up, I suspect it will
go down as the set gets going, no surprise there...

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Hello there...from my read of the schematic the volts on these should be:

6SK7 #4 -4.3V #6 129V #8 165V
6SH7 #4 -5.2V #6 135V #8 134V
6SN7a #1 I don't know! #2 88V

As for resistors, 228, 153, 159, 157, 158, 160 all test dead on. I replaced 154 and 155 because they were a smidge high.

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Yes, and did you not post these readings:

Originally Posted by Chris K View Post
I really don't see a smoking gun here except for the lower voltages associated with the reduced 135V line being bled off to another voltage line source.

6SK7 #4 -3.6V #6 96V #8 187V
6SH7 #4 -4.3V #6 104V #8 103V
6SN7a #1 -1.3V #2 68V

With each G1 a little higher than what the schematic calls for?

Anyway, Please post all the Minus Voltage Sources, I'm interested...
Thanks....



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... Higher G1 voltages will
mean all the tubies conduct just a little bit more for each one.... and you know
what that means.... More Ampies being used.

Higher negative G1 voltage with respect to cathode reduces plate current. Plate voltage is in reverse phase to the grid.

Yes that's what I got (I edited the should be voltage on the 6SH7 pin 4 in my previous post. It's not -18V...its -5.2V

https://imagizer.imageshack.com/v2/1024x768q70/922/hHkYdH.jpg

https://imagizer.imageshack.com/v2/1024x768q70/922/zYMbrH.jpg

Higher negative G1 voltage with respect to cathode reduces plate current. Plate voltage is in reverse phase to the grid.

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Look at the voltages, Readings Vs. Schematic the readings are closer
to 0, not closer to -7V cutoff. They are increasing with respect
to cathode 0. -3v is higher than -4v.

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I don't have those caps in my TV...it has the resistor-like caps all of them in the 6.3V filaments to ground.

These were on my +135v IF line. :tears: and caused me pure hell in my FADA, even though the parts list called out ONE type, there were 2, the white with the weird leaking, and the tube type that seemed OK.

What's in yours? :O

These things

https://imagizer.imageshack.com/v2/1024x768q70/924/2pEc4v.jpg

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Is the sound ok? You see that full water hose from the PS goes to the 6K6 through
some very small value resistors, and a low resistance output transformer....

Is C224A ok?

What voltage is on pin 5 of 6K6?

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Yeah, they do look like Resistors! :D
yours is much cleaner! and lacking that mysterious brown stuff that came out of mine! :D

The sound is diminished. I have to turn it up all the way to hear a decent tone out of the Sencore VA62. I put a 47uf electrolytic in for the 20uf C224 A section. Too big? I didn't have a 22uf cap for it. It's supposed to be 20uf. The voltage on pin 5 of the 6K6 is -17.6V.

Actually no there is a 22uf electrolytic there...new Nichicon

Interesting thing...as I said before, the horizontal oscillator is putting out a clean 15.75 KHz sine wave but when I look at the waveform on the plate of the 6AL5 Horizontal Sync Discriminator, the waveform trace looks fine...it's just unstable and jumping all over with instability in the picture. I don't know if that means anything other than crossing the oscillator off the troubleshooting list. The 6AL5 is new and I've put 3-4 different ones in the socket with the same outcome.

Still waitin for that cold-start test on the 135V rail. :scratch2::D

Still waitin for that cold-start test on the 135V rail. :scratch2::D

Oh I did it. It's in this message post salad somewhere. Close to 300V DC on startup, then after 30 seconds or so, it started a slow decline over a minute down to 105V DC

Yeah, they do look like Resistors! :D
yours is much cleaner! and lacking that mysterious brown stuff that came out of mine! :D

That's just how they are made. The brown stuff is how they sealed the ends. Seen them many times.

That's just how they are made. The brown stuff is how they sealed the ends. Seen them many times.

I don't mean the dark red/brown ends, I mean I could not ID the stuff on the body/ middle.
http://suzaku.live-evil.org/1500pf2.png
that's not flux. no idea where it came from. the cap was all alone not near anything else. how did that get on there, unless it came out of the cap?

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Well, I think there has to be something wrong keeping the PS from getting close to the
numbers on the schematic, I thought the audio circuit, but it doesn't look like it.... So
you may want to try doing the fire up from cold and looking for some part getting too
hot too soon, Audio output transformer, maybe primary windings leaking current to
ground. You may also want to run it with a meter on the 135V line, & pull out a tubie
one at a time, and see if a circuit lets that line come up a lot, then possibly poke
around in that circuit. (Just take out 1 tubie, then put it back & remove another
one.) You know taking out Vert. Horiz, outputs are going to make a big
change - cause they use more ampies....

Also, know that power supply problems may and often will effect many other
parts of the tv, so Horiz. jumping instability may be PS problem.....

You also could put this thing out in the yard and light it on fire, sit back & toast
a marshmallow and start another set, and be ahead of the game this time
next week..... In my book, setting it on fire is always an option.....

You also might want to cut the line from the two rectifiers before they
feed the entire set, and measure the current and see if it exceeds
what the 5U4's are rated for..... If it does, then for sure you
know there is a excessive load someplace.....


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Oh I did it. It's in this message post salad somewhere. Close to 300V DC on startup, then after 30 seconds or so, it started a slow decline over a minute down to 105V DC

Ah, missed it.:o Got a question. The junction between R186 (6750Ω) and R240 (12Ω) should go to chassis ground. Does it? And does R240 correctly measure 12Ω?

Since that junction is the neutral point between the positive and negative supplies, if it lost connection to ground, it would be "floating" and could cause really crazy supply voltage readings. Just a shot in the dark

Yeah it does and I replaced it with a new 12 ohm resistor just in case although the original was just fine.

Something to think about, at first my 130v rail was @ only 107V – 109V, then it was suggested that I remove one side of R130 and see what effect it had, it then came up to 138v stable, pointing me to the problem area.

I also fed capacitor coupled composite video into grid 1 of the 1st video amp (after removing the 4th IF tube), at the time and got a very good picture.

Something to think about, at first my 130v rail was @ only 107V – 109V, then it was suggested that I remove one side of R130 and see what effect it had, it then came up to 138v stable, pointing me to the problem area.

I also fed capacitor coupled composite video into grid 1 of the 1st video amp (after removing the 4th IF tube), at the time and got a very good picture.

I'll try both of those things tonight. Previously, I sent in an IF signal through the first and then second IF stages and got a picture with the same symptoms. I haven't tried composite directly into the video amp yet.

Something to think about, at first my 130v rail was @ only 107V – 109V, then it was suggested that I remove one side of R130 and see what effect it had, it then came up to 138v stable, pointing me to the problem area.

I also fed capacitor coupled composite video into grid 1 of the 1st video amp (after removing the 4th IF tube), at the time and got a very good picture.

Sorry for my ignorance here...what size and what type cap did you use for the video feed? Let me see if my limited but slowly growing knowledge of this stuff is correct...the reason for the capacitor is to protect the source from DC in the TV?

The exact value is not super critical, since there is so little voltage to start with, people have used a .1 or .01 film type with out problems.

The exact value is not super critical, since there is so little voltage to start with, people have used a .1 or .01 film type with out problems.

No change in symptoms with a composite signal into the 1st video grid. R130 is reading 180 ohms and not 150 ohm. I got the freeze spray today.

No change in symptoms with a composite signal into the 1st video grid. R130 is reading 180 ohms and not 150 ohm. I got the freeze spray today.

BINGO!

That is out of tolerance for 10%
and you may have others, some say that having it go higher than 20% is OK, but in my case, I checked each and EVERY resistor, using this site, https://www.allaboutcircuits.com/tools/resistor-color-code-calculator/
If it tested within 10% or better, I marked it with green paint, if it checked below, I replaced with a new 1% resistor, This could be your problem, not sure, but It is what I had to go through

Replaced the R130 resistor with a 1% 150 ohm and it is better. It's not stable, it still twitches but it hasn't gone completely out of sync like it was before. Voltage hasn't changed much but I think going through this and replacing resistors across the board in the IF circuits is something I should do. The 1500pf caps as well.

I think I'm going to replace all of the resistors in the sync circuit first even if they test good when cold. I was fooling around with the freeze spray on resistors in that circuit and the picture had some transient stability.

Replaced the R130 resistor with a 1% 150 ohm and it is better. It's not stable, it still twitches but it hasn't gone completely out of sync like it was before. Voltage hasn't changed much but I think going through this and replacing resistors across the board in the IF circuits is something I should do. The 1500pf caps as well.

Not sure why you chose 150s to replace the 130s, as the IF is always picky, but most likely, as you go through the whole set and replace all out of tol resistors no matter what section, things will get more stable, this of course will take a lot of time, it took me 2-3 months to do mine staring with a very unstable pic, to what I have now.

Those resistors are 150 ohm in my TV

There's one test you could do 'experimentally' to raise the 135V source, just to determine whether the problem is due to low voltage there, or not. Just clip open either end of R186c (6750Ω), and insert a resistor in series with a pair of clip leads. I would try first a 1K, then a 2.2K, and maybe a 3.3K, all at least 2 watt rated. If raising the voltage doesn't help the problem, then you know. Just re-connect R186 and pursue another route.

I’ll give it a try. I found 2 more 270pf caps in the IF (5 all together) and I will say after replacing all of them and a few low ohm out of tolerance resistors in the IF the picture is more stable. A lot of ringing, edge distortion and twitching still but noticeably better.

Quick update. Still going through the chassis replacing all of the 1500pf caps in the IF and testing/replacing resistors one by one. What an impossible mess to get at these maddening things. The video IF is a crowded spiderweb full of coils, resistors, petrified insulated wiring I'm hesitant to move and the grounding caps, mostly at the bottom of it all. Fortunately, the ETF had beaucoup service data on this chassis that included a wiring diagram that has been extremely helpful.

The picture has gotten worse but I expected that. The horizontal is going to need to be realigned after all of this is complete. At this point, I don't expect to find a smoking gun where I make a replacement and bang...everything works. The video is now rolling horizontally like a sideways vertical hold issue. Looking at the service data, that's probably due to the phase control slug in T-108 needing adjustment but there are multiple tuning parameters in the horizontal circuit that need to work in concert so attempting to adjust slugs and drives right now to find the magical tuning point where everything is stable is pointless.

Someone has done extensive work on this TV throughout its lifetime and some of the component overcrowding is due to that but most of the IF is original. I don't know how any tech diagnosed and serviced this back in the day. For me, at least, it's a big challenge.

I’ll give it a try. I found 2 more 270pf caps in the IF (5 all together) and I will say after replacing all of them and a few low ohm out of tolerance resistors in the IF the picture is more stable. A lot of ringing, edge distortion and twitching still but noticeably better.

The likely reason there is ringing and edge distortion is because changing the capacitors in the IF section has thrown the IF out of alignment.