Hi guys uship just dropped off my new RCA TV. I don't know the actual model. There's an interesting story behind this set.apparently the previous owners dad was taking a tv repair course by mail and he believes this was going to be the guinea pig. He was cleaning out the house and found it in the Attic. Along with an 8 mm projector and all the books for the course. Once he finds them he's going to send them to me. Anyway I carried the set down into my basement it's shockingly heavy, and opened it up just to see what was going on. I heard a lot of rattling so I was concerned. The first thing I noticed when I opened it was a brightener so I was pretty upset, then I noticed he stole every tube out of the set but wrote down where each tube goes. I hooked up my picture tube tester just to see and the tube tests extremely strong with great cutoff. Has anyone seen a set with a good tube and a brightener installed? Anyway, I wanted to give reforming the caps a shot just to see if I could get any action out of the set. I used a 25w appliance bulb on my dim bulb and without any tubes it lights at about 50% brightness. Then I plugged in my solid state 5U4 and it went to full brightness for a second then dropped right down to the brightness before the 5U4 was installed. I see that at some point the main filters were replaced. I just don't know when. Is it possible they aren't shorted? I know I'll be recapping the set, but I'd like to put tubes in and see how it works.

First with the 5U4 out there is no voltage to the filter caps. Do the
dim bulb again with it in.
If it is a series string pull any tube out & run that test. If a // string
pull the hoz output tube. If things look good put the tube back in &
see if you get a raster in < 1 mn. If not the trouble shooting starts !
IIRC this is a "doughnut" chassis. They are a bitch to work on so take it very slow ! The idea is get the power supply up then the HV for a raster.
At that point you can judge how far to go.
The filter caps will probably work but need changing eventually, For now dont
spend the $$.

73 Zeno:smoke:
LFOD !

Anybody could walk in to a store and buy a brightener. I've seen them on good tubes more than once...Most interesting case was a 1968 Zenith color. The set was low hour and the CRT was STRONG, but the 25KV from the flyback was more like 11KV...It worked surprisingly OK like that...The root cause was the original H output being weak... possibly the HV rect too.

It's not uncommon to see sets stripped of tubes. Home repair attempts usually involved bagging them and bringing them to a drugstore tube tester, if they were fine they might not go back in since the problem isn't a bad tube and that's too much work....
Also repair shops when they condemn a set will offen strip the tubes, then knobs and similar common trim, then toss the cabinet and rob bits off the cabinet....In some cases those steps didn't all happen at once.

I finally got all the tubes and fired the set up. The cap for the audio section is bad it hums like crazy so I just pulled the audio output tube for now. This is all I get on the screen. I did substitute one of the tubes in the tuner so I thought maybe that was the issue. So I took my pattern generator and hooked it up to the grid of the video output tube, and couldn't pass a signal through. I tried a few different tubes nothing made a difference. I'm just curious where I should look next I figure I could try to learn something from this before I just blindly recap it. If nobody has the schematics I could take some pictures of the Sam's I have. I didn't get the digital I bought a folder set off of eBay.

If you can't get anything from the grid of the 6AQ5 video output tube, start taking voltage readings there. Check for open contrast control, peaking coil off of pin 5 the plate, should have 190 volts on it, screen, pin 6, 255 volts. Does the brightness control work?

If you can't get anything from the grid of the 6AQ5 video output tube, start taking voltage readings there. Check for open contrast control, peaking coil off of pin 5 the plate, should have 190 volts on it, screen, pin 6, 255 volts. Does the brightness control work?


The brightness and contrast controls work. What's interesting is the black bars spread a little as I adjust contrast. The horizontal hold doesn't do very much. I haven't been deep in the set but I'm wondering if it's a coil. I turned it about 4 complete circles before anything happened. Also there is a little ringing from the yoke.

Also I checked the 255 volts source and tube heater voltages on other tubes but I did not check there. I will check and report back.

OK I had a chance to check the 6AQ5 video output tube. The first value is the Sam's voltage the second is mine.

Pin Sam's Volt My Volt

1 0 1.6 VAC
2 18 33 VAC
3 Ground Ground
4 6.3 6.3 VAC
5 190 139 VDC
6 255 227 VDC
7 0? 1.5 VAC

I believe the Sam's says 1 & 7 are both 0V it shows this as 1-7.

So what I'm seeing is my voltages are low on 5&6 would this be low enough not to be able to pass a signal? I tried sending a signal in on Pin 1 and on Pin 7. But saw no reaction at all on the screen.

Also how come I didn't see a negative voltage listed to turn the tube on?

I cant find my larger tube test socket to test the 6AW8 video amp. But am I right in thinking if I sent a signal through on the grid of the video output tube I should get some kind of a picture from my signal generator?

I just decided to do the resistance readings on the tube socket. 1-4 were just about perfect
5 was 4.32k Sams says 3.6k
6 was 37 ohm Sams says 38
7 was 0 Sams says 470k

I can't find where pin 7 goes on the schematic. Also I'm wondering if C2 Section C is dragging down the voltage on pins 5&6.

Have you tried swapping the 6AQ5 video output tube with one of the other 2 6AQ5s in the set? I don't think your voltage or resistance measurements are so far off as to cause this problem. The chassis uses an "extra" video amp stage, that why the video is fed into the grid of the CRT instead of the more common cathode connection. Is your video source signal negative or positive? Pins 1 and 7 are tied together inside the tube, usually only one socket connection is used. If you check voltage or resistance with the tube out of the socket you'll probably get very different readings on them.

I actually took all the readings with the tube out. And I did try swapping all 3 tubes l, but it made no change. I never checked if the video source is negative or positive it's an old Heath kit signal generator. It actually has two terminals on it I assume the red is positive which is what I was putting on the grid, and I was putting the black to the chassis

Find another RF source like a game, VCR etc.
Kinda looks like a wide open filter cap. If it is you should get 2 bars rolling
through the pix.
Could be H hold. Some have a pot & a coil. As you adjust it the lines will get closer or further apart if thats it.
TIPS
The filter caps will almost always open & often have mung leaking out. Quick
test is just hang a 50mfd to 100mfd , 450 V in // & see if any problem goes away. Saves time & $$.
If H hold uses a pot for H hold center it then adj the coil.
Little coils in the video can just be jumped out. If its open the set will get
a pix again but it wont look right. Another time saver.

73 Zeno:smoke:
LFOD !

Find another RF source like a game, VCR etc.
Kinda looks like a wide open filter cap. If it is you should get 2 bars rolling
through the pix.
Could be H hold. Some have a pot & a coil. As you adjust it the lines will get closer or further apart if thats it.
TIPS
The filter caps will almost always open & often have mung leaking out. Quick
test is just hang a 50mfd to 100mfd , 450 V in // & see if any problem goes away. Saves time & $$.
If H hold uses a pot for H hold center it then adj the coil.
Little coils in the video can just be jumped out. If its open the set will get
a pix again but it wont look right. Another time saver.

73 Zeno:smoke:
LFOD !

Ok so maybe I will pick up 2 adaptacaps and just change the filters first. I was tempted to unsolder each lead and use my Heathkit C3 to check for leakage. It just bums me out because I was hoping to learn the symptoms of the failures.

If you are just starting get an old book that shows block diagrams.
It will describe each block, function & symptoms. Thats how I started
many moons ago. Maybe someone can recomend a few.

At this point the filter caps are good to change. You know you have a brite CRT, HV, so yoke, CRT, & flyback are good.

73 Zeno:smoke:
LFOD !

Ok so I replaced capacitor C1, the shame of it is the whole thing tested good except the audio filters. I also changed capacitor C62. When i tested it for leakage it tested good then slowly started to leak. I did replace it with one of the yellow plastic ones bevause it was all I had. Cap c62 goes between pin 5 of the video output tube and pin 2 of the picture tube. While it was out I ohmed out coil L50 and it measured 8.5 ohms instead of 7 so I think it's fine. We'll after starting the set up, I now have no picture. There is only 50v coming out of pin 5 of the video Amp instead of 190, pin 11 on the picture tube is showing 1.8v and pin 10 is about 360. I hear the high voltage running. So I'm going to take another Crack at it tomorrow maybe one of the new caps is no good. I tested them all for leakage before install but who knows.

Here is a link to the Sams on my Google drive
https://drive.google.com/file/d/1fKnLJH-ugOJM6woTJFSGYHdRkJ_SeVvi/view?usp=drivesdk

Hey guys so I've been trying to selectively recap this set, to try and learn, the symptoms of failures in each of the sections. Right now I fully recapped PC 103. However I still can't pass a signal to the picture tube. Also I've lost a little bit of vertical deflection since the recap.

In addition to recapping PC-103 I have replaced C63, C64, I've replaced all three sections of C1, c116, c117, and c118. Out of all these caps only C62,C63, C65,c116, and 1 section of C1,were bad. The rest tested good surprisingly but I didn't want to have to unsolder the boards again if I didn't have to.


I'm going to recap the vertical board today, to hopefully fix the issue with the vertical deflection. What's sad is before I recapped board pc103 and replaced the filter caps I actually had full deflection but couldnt pass an image through the TV. I don't know if maybe it's just coincidental and capacitors are failing on the vertical board. I also tested coil number 50 and it tests at 7.5 ohms.


I tried putting a signal in on the 6aq5 on pin number one and couldn't get an image on the screen, then I tried pulling V6 the third video If and putting a signal in on pin number seven and still couldn't pass a signal. My Heath kit signal generator only puts out about 1.5 volts in the video setting is it just not enough to pass through? I also tried putting the lead from the heath kit directly to pin number two of the picture tube and that didn't do anything either.

I'm not sure what to make of all this, it seems to me if I could pass a signal over pin 1 of the video output it should display on the screen. I tried removing V6 to try and keep the IF from sending a signal in and over powering my signal. What am I missing?

When no signal goes through, it's a clear indication that SOMETHING is wrong, but not much help in determining WHAT. The next thing I would do is check voltage readings to try to isolate the problem area.

if you wish to try to feed in video, the best place to try is point C, on the SAMS, right after the video det, feeding into the grid of the video amp.

You mentioned L50, but what about the others?
L47,L48,L49? Everything in that area, if you put a 1.5 signal at the grid of V7, (point C) and got no reaction on the screen, with known good tubes and bias within spec, you have a problem from point C to the control grid of the CRT, this will also kill sound, if the video amp has no signal on the plate to give to the sound IF.

You mentioned L50, but what about the others?
L47,L48,L49? Everything in that area, if you put a 1.5 signal at the grid of V7, (point C) and got no reaction on the screen, with known good tubes and bias within spec, you have a problem from point C to the control grid of the CRT, this will also kill sound, if the video amp has no signal on the plate to give to the sound IF.


I only looked at l50 because I was trying to figure out the path from the video output tube directly to the picture tube. I figured if it's not passing from there to there it had to be a problem in either the capacitor or that coil. Is this flawed thinking?

Also I'm going to try the video amp just to see. I was doing only the video output V8

Be meticulous, starting from the det V6 to the CRT V20, check every coil and resistor, it could be any number of things. I normally take a green marks all ink marker, and put a little green dot on things that check 10-15% to what they should, and think about replacing parts that don't.

Be meticulous, starting from the det V6 to the CRT V20, check every coil and resistor, it could be any number of things. I normally take a green marks all ink marker, and put a little green dot on things that check 10-15% to what they should, and think about replacing parts that don't.



Okay, so I shouldn't be trying to move back from the CRT I should be trying to move towards it when I'm troubleshooting? I was thinking start at the closest point to the crt and inject a signal if it works there l move back one section and do it again until it doesn't work.

Work in sections, you know you have HV, sweep, V+H, but going on that you had no results putting in a singal at point C, and going on the assumption that signal was good, and put in correctly, there should have been a reaction if the circuit was working from point C to the CRT, so there must be a fault.
In order to input a signal at the CRT, you need a negative signal at 50v PtP, only a few video equipment can do that, so it's best to work from the lower end and check things over.

If you happen to have an audio generator or a low frequency RF generator with several volts of output you could that as a signal generator. It won't put out a standard pattern but you'll get black and white patches (whether they form spots or bars depends on the instantaneous frequency difference between them and the sweep). Hell, if the set isn't hot chassis you could capacitively couple 6.3v from the heater into the video amp grid....if the hum bar gets through you know that the amp is passing signal.
There's no perfect substitute for the right test equipment but if you're smart and desperate enough there's often some workable options.

If you happen to have an audio generator or a low frequency RF generator with several volts of output you could that as a signal generator. It won't put out a standard pattern but you'll get black and white patches (whether they form spots or bars depends on the instantaneous frequency difference between them and the sweep). Hell, if the set isn't hot chassis you could capacitively couple 6.3v from the heater into the video amp grid....if the hum bar gets through you know that the amp is passing signal.
There's no perfect substitute for the right test equipment but if you're smart and desperate enough there's often some workable options.

Work in sections, you know you have HV, sweep, V+H, but going on that you had no results putting in a singal at point C, and going on the assumption that signal was good, and put in correctly, there should have been a reaction if the circuit was working from point C to the CRT, so there must be a fault.
In order to input a signal at the CRT, you need a negative signal at 50v PtP, only a few video equipment can do that, so it's best to work from the lower end and check things over.



I do have a BK1077B that I just restored, I'm just a little nervous about blowing it up. I was reading in the manual that it has a negative signal generator, would that put out enough? I was using the Heathkit because it's a little more disposable....

I'm not sure that the BK1077B can put out a 50v PtP signal however, the best way IMOH, is to start from V6, and check that all is OK in the path to the CRT, (coils , resistors ) , you will most likely find tired / worn resistors, especially the lower resistance ones on the cathodes, they love to go up in value, making the tube work very poorly.

I have seen this a lot in sets of this era.

On most sets if brightness isn't set too high you can get a faint image (or contrasting nonsense as it probably won't be synced) injecting at the CRT with max amplitude from the video output of a B&K 1077.

The 1077B has a large high voltage cap on its video output jack to protect it so it should be fine. The 1077 is a fairly rugged piece of gear intended to be miss-connected occasionally.

Don't forget an open trace on the PC board. I once saw a guy replace 5 chips on a Beta deck (broadcast version) and it turned out to be an open trace on the PC board.
A real simple video generator can be found here:

http://pa2rf.blogspot.com/2013/08/diy-video-pattern-generator.html

I've made several and they work well for analog tv's and monitors.

Just wanted to follow up guys, I'm not done with the vertical board unfortunately the RCA schematic is wrong, shockingly enough to Sam's is right. You would think RCA would know what was in their TV. I ordered off the RCA parts list so I didn't order a .068 capacitor for the board. Interestingly enough though so far every cap has been open in the vertical section. Literally not one good one. I'm surprised I didn't have a collapsed vertical.

Sounds unusual... how are you testing the caps?

jr

Sounds unusual... how are you testing the caps?

jr


I have a heath kit C3 capacitor checker. I checked them all for leakage and everyone was leaky. Then I tried a brand new one and it tested good so I know my Checker is working. I did recap it in the past so it should be pretty stable

Nothing unusual for old paper “bombs”, it would be more surprising if one checked NOT leaky and good.

I have a heath kit C3 capacitor checker. I checked them all for leakage and everyone was leaky. Then I tried a brand new one and it tested good so I know my Checker is working. I did recap it in the past so it should be pretty stable

Thanks for the clarification... “leaky” rather than “open” makes perfect sense.

jr

Thanks for the clarification... “leaky” rather than “open” makes perfect sense.

jr

Honestly most were very leaky, like to the point where the tester would start to test then the eye would pop back open like there was no cap at all. but I did have 2 that were open.

Hey guys I had a couple minutes last night to take a peek at the TV. I accidentally blew up the heath kit, I put it on the wrong terminal of the third IF and let the smoke out of it. So I hooked up the 1077 to pin number two of the 3rd IF and was able to pass a signal.,it wont lock, and there's a black bar rolling through it, there's also these white stripes going through the picture, almost like you were looking through louvers. They're not the usual light retrace lines they're dark lines a little more narrow than a number two pencil. I was able to pass audio through also. I did have to have the signal generator turned up all the way though to get an image. I went back to the second IF and tried injecting a signal on pin number one which looks to be the Grid on the Sam's and could not get any signal to pass I tried another 6DE6 that didn't help, so I assume that's where the problem is, or atleast one of them. I'm a little concerned that it could be a bad IF can and then this set becomes junk. I didn't get a chance to check voltages, we were going fathersday shopping and my wife wanted to leave. But I will follow up.

I snuck downstairs for a few minutes today and had some interesting results. First somehow all the sudden I can pass signal through all 3 IF stages. I done know why that changed but it did. I still cant get the picture to lock and I still have distortion in the picture. The IF voltages are almost dead on to the Sam's except for the 2nd IF. According to the Sam's I should have 125V on pins 5&6 according to the RCA Schematic I should have 231 on Pin 5 and 252 on Pin 6. So I'm not sure of what to make of this. Then The RCA Schematic shows Pin 1 as having 113V where the Sam's shows -5V I have .03V, I'm not sure what to make of any of this....

I spoke with a few people the consensus is that the RCA Diagram is right. I didn't take into account that the resistors aren't big enough to drop the voltage down from 255 to 125v. So I started tracing out Pin#1 of the 2nd If. the 150K 5% resistor read 189k so that is probably part of the issue. I only have a 30 MHz scope, If I just go through and change all the resistors, will I still be able to align this IF? I'm afraid to knock them out of alignment by changing all the resistors. I can tell someone else has worked on this IF board, so it maybe problematic. I would love to just put fresh Discs and resistors in here so I can set it and forget it ha-ha. But I don't want to be digging my self into a hole.

If you have the equipment (sweep marker generator and oscilloscope) and skills to do a television alignment replacing the resistors shouldn't be an issue for doing alignment (I've found on early color RCAs replacing the out of tolerance resistors often eliminates the need for alignment)... Though you need to use carbon composition resistors and not carbon or metal film resistors as the new film types often have somewhat inductive design that can do odd things at high frequency. Ceramic discs almost never fail so don't monkey with them unless they test shorted or open.

A lot has gone on since my last post. I kind of wish I chronicled it a little better.

My iIF Board problems ended up being a bad solder joint. I could only find 5% carbon composition resistors through Radio Days and it took them a week to ship. So I got impatient and put the board back together. While I was at it I went through the board and reflowed every single solder joint just to see what would happen. I put it back together and all the voltages were dead on.

I set the TV up and my horizontal was going crazy. I asked advice from someone and he told me to adjust the horizontal coil and the horizontal wave form coil. Doing this got me a decent picture, but the top of the screen was twitchy. He told me that's probably the TV having trouble syncing. So I recapped the sync separator board, and at the same time I had lost audio completely so I recapped the audio board. I actually had open caps in both boards. I have to go through my notes to tell you guys which ones but it was very interesting.

At that point I turn the TV on and the horizontal was off again so I readjusted the whole horizontal. And had a pretty decent picture. I went to bed last night, the next morning I turned the TV on and had a complete loss of horizontal adjustment again, this time I could adjust it with the knob on the Tv, I added a picture of this down below. The picture is what the TV looks like every time you turn it on after it's sat overnight. If you turn it on and off while it's warm the picture comes back like nothing's wrong, and it doesn't lose horizontal sync the whole time the TV is on. But I have to set the horizontal everytime I turn the TV on.

The next thing is I tried to set vertical linearity for about 2 hours. Using the B&K 1077 slide I cannot get that circle around no matter what I do. The only way is to shrink the vertical so that there's an inch missing on top and bottom, otherwise it looks like an egg. I can't make the circle round is there a trick to this?

The last thing is the picture isn't very sharp and I'm getting these lines going left to right on the screen they almost look like the digital fake scan lines they add on YouTube videos and things like that to try to make them look old. Is there a way to fix that?

I made 3 youtube clips of the TV playing a DVD, and doing crosshatch. I also took some pictures.

Here's the B&K doing cross Hatch https://youtube.com/shorts/QKVGKsI1D1A?si=xqo0HzbUOCfrsj6l

Here's a movie playing https://youtube.com/shorts/jhDxmbxGCyo?si=lrArAp8wsk8yosCy

Here's the same movie and I'm trying to make the picture sharper playing with fine tuning and a few things
https://youtube.com/shorts/DipkKuuvZec?si=z_S8ls9-kOJzibN7

Regarding: Here's a movie playing https://youtube.com/shorts/jhDxmbxGC...ArAp8wsk8yosCy
It looks like the brief intermittent could be an intermittent antenna or tuner connection. Time to wiggle wires and tubes and knock on various things gently with a screwdriver handle to see if you can make the set jump like this.

Regarding "sparkles" in the third video, I can't see them in your video. Do they look like they could be sound carrier dots (would dance around with the sound track)?

Edit: is the movie playing from a DVD? What happens to the "sparkles" when you go to a menu with no sound?

Regarding the circle distortion, some or all could be coming from the B&K.

Two ways to check:
1) (not the best) connect the B&K to a known good set and see what it looks like
2) (better) get a guaranteed good source, like a test pattern DVD.

Regarding the circle distortion, some or all could be coming from the B&K.

Two ways to check:
1) (not the best) connect the B&K to a known good set and see what it looks like
2) (better) get a guaranteed good source, like a test pattern DVD.

I'm going to try the test pattern DVD and start wiggling and tapping on the set. Any idea why I have to reset the horizontal every time I turn the TV on?

Could be something like a carbon comp resistor drifting with temperature or a marginal tube taking a long time to get up to speed.

As for the screen distortion, agree it could be the B&K. I also wonder if the yoke has slipped back a bit? Make sure it is firmly all the way up against the bell of the CRT.

Could be something like a carbon comp resistor drifting with temperature or a marginal tube taking a long time to get up to speed.

As for the screen distortion, agree it could be the B&K. I also wonder if the yoke has slipped back a bit? Make sure it is firmly all the way up against the bell of the CRT.

I'll check the yoke.

If I swap out the resistors in that area do they still have to be carbon comp like on the IF board?

All the tubes are new, but I haven't put them in the tube tester to verify they aren't nos duds. I found that my tube tester tends to pick up issues after I let the tubes get nice and hot in use. So I'll run the set for an hour or so and then test each tube in the set.

I use my metal film for all replacements. Inductance is trivial and no effect at these frequencies has been my experience.

I'm going to try... and start wiggling and tapping on the set. ...

Just for a bit of fun trivia: at the end of the assembly line, Zenith (and other makers) had a final test where the set was pounded on three sides to look for any intermittents. Zenith used a kid's solid rubber ball mounted on a wooden dowel for a handle, and called this the "JWS" test, for "Jumps When Struck."

Coulda called it the 'GWT' test (glitches when thumped). :lmao: