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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Mon 14, 2019 5:28 pm 
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MattPilz wrote:
QUESTION 2: Can anyone explain why the new yoke has a capacitor across one half of the horizontal coils, but the original did not?

QUESTION 3: Any further explanation as to what this fifth wire addition actually achieves? It seems it might just feed a little more resistance into that coil?

The capacitor in the new yoke is to improve the horizontal linearity. On the old yoke the fifth wire connects to a network of a resistor and two capacitors which serve the same purpose as the capacitor in the new yoke. In fact one of the two capacitors in that network is in the same electrical position as the capacitor in the new yoke. If you used the new yoke without the fifth wire and kept that cap that came with the new yoke, it may well work almost as well as adding the fifth wire and removing that cap.
The effect of either that cap in the new yoke or using the fifth wire instead will be a small correction of the horizontal linearity.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Tue 15, 2019 6:37 am 
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Thanks for the info about the yoke, yes I am not messing with it but was mostly just curious.

Tonight I replaced C62 (mica) but it didn't show any improvement in the vertical roll. I also temporarily took M7 out of circuit and likewise can't say I noticed much visual difference, if anything it got a little worse. I should be able to try and build the new M7 tomorrow but still have the original too in case that fails.

I will have to start checking more voltages on the tubes this week. I also have ordered a frequency/signal generator as a means of helping learn my oscilloscope in a controlled manner. Finally I have a variety of silver micas and ceramic capacitors en route so if any of those may be bad I will be able to replace many of them. But as I've read they rarely need to be replaced so that would be a last option. I will still replace the old plastic micas though (the rectangles with colored circles) there are four of them on the sync circuit.

Can we definitively rule out the chance it could be a malfunction with the vertical transformer itself?

I would like to use the 1077 to experiment with injecting signals at various points and messing with the vertical elements, but this issue really only occurs with moving images of varying black balance so I'm not sure how effective it would be if it just injects the static test slide (am still learning about using the 1077).


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Tue 15, 2019 12:25 pm 
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the rectangular mica caps with the colored circles on them are domino caps and dont need to be replaced unless proven to be bad.

im just curious why did you replace the origional yoke? i dont recall reading anything that suggested the original yoke is bad.

if you are worried ohm out your vertical transformer. if the readings are within spec it is not bad. i would think if your vertical transformer were bad you would loose vertical sync all together.

set up your brightness and contrast correctly. if memory serves set contrast control about mid way turn brightness all the way down and back up till you can just see the picture good in a normally lit room then tweak contrast control for a decient black white leval. the 1077 has bars on the test slide for this purpose.

your remaining vertical issue may be a problem with the modern signals you are using ie a video game and not a problem with your tv. try watching a tv broadcast using a converter box or cable box if you have one and see if the issue persists. a political debate would be perfect for this since dark suits and ties with white shirts will provide lots of contrast.


Last edited by thomas13202 on Oct Wed 16, 2019 5:37 am, edited 1 time in total.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Tue 15, 2019 5:29 pm 
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The only problem a vertical output transformer could have that would still provide some vertical deflection would be a short between two turns of a winding. But that would result in a severe reduction in height. Something like the maximum height being less than 1/4 of the correct height. And that would have absolutely no effect on the ability to synchronize the vertical.

If you remove M7 then you will absolutely have no vertical sync. The purpose of that network is to couple the vertical sync into the vertical oscillator while filtering out the horizontal sync signal.

thomas13202 wrote:
a political debate would be perfect for this since dark suits and ties with white shirts will provide lots of contrast.
;

Gaaaak! :!:
If you do that you should absolutely turn the sound all the way down and turn it off as quickly as possible.! :!: :)

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Tue 15, 2019 5:58 pm 
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Tom Schulz wrote:
The only problem a vertical output transformer could have that would still provide some vertical deflection would be a short between two turns of a winding. But that would result in a severe reduction in height. Something like the maximum height being less than 1/4 of the correct height. And that would have absolutely no effect on the ability to synchronize the vertical.

If you remove M7 then you will absolutely have no vertical sync. The purpose of that network is to couple the vertical sync into the vertical oscillator while filtering out the horizontal sync signal.

thomas13202 wrote:
a political debate would be perfect for this since dark suits and ties with white shirts will provide lots of contrast.
;

Gaaaak! :!:
If you do that you should absolutely turn the sound all the way down and turn it off as quickly as possible.! :!: :)

Yeah, I don't want to encourage anyone to listen to a gaggle of crazy people arguing with each other over how to go about ruining the country....
When we're down to 2 mostly sane adults then it will be worth watching.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Tue 15, 2019 6:23 pm 
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Quote:
im just curious why did you replace the origional yoke?

When I saw a NOS replacement that had a perfect casing on it I got it, since my attempted remedy of my original using gasket maker applicant wound up very messy. So I decided to use the new and I transplanted the plug end from the old. More troubling though, I tried to open the old yoke back up to assess the connections and the moulding I had applied caused the entire plastic coating to shatter which also dislocated the thin wires from the coil connection points... I still do have it and potentially could fix it if needed but I definitely screwed up by bothering with the replacement when the original did seem to still be working ok. I should had left the original alone and bought new octal plug for this one as a spare. I'm chalking it up as another important lesson learned (one of many during this adventure).

Quote:
If you remove M7 then you will absolutely have no vertical sync.

Interesting. Because I tried it again without M7 and it still exhibits the exact same symptom and visuals as when it was in place. I am able to get the vertical stationary as before by carefully adjusting vertical hold, but then it gets off track depending on the brightness or picture on screen. So maybe this is a strong candidate as the cause and it has never worked right. When I adjust vertical hold with or without it there is no feeling that it is actually locked in sync like I see on other CRTs I basically just have to keep slowly turning hold until the image generally aligns to the screen and stops rolling.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Tue 15, 2019 6:50 pm 
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Matt have you measured all the resistors in the Vertical section (V7 and V13)?
I agree with what Tom wrote.
As far as the sync is concerned M7 does seem to be a good candidate for being the problem.
I suspect that since these couplates are a combination of resistors and capacitors that are made in the same process that there is some compromise and one or both go bad. Other components around that section of V7 could make the circuit hard to sync however.
Modern analog TVs had better (technically more complicated) sync circuits.
The circuit around V13 and the output transformer is responsible for generating the correct wave shape of the vertical sweep. If the shape is wrong than the picture linearity is off or distorted. If the size of the waveform is wrong then the height will be wrong.
Transformers with iron cores have a problem that can be due to the DC current through them. The iron can only be magnetized only so much then it saturates. Once the core saturates the AC signal cannot get bigger. If the DC current is too high, the peak of the AC signal limited. This would make it look like the top or bottom is cut off. Too much DC current could be due to problems around V13. There could be a defect in the transformer that would make the correct current saturate it.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Tue 15, 2019 7:00 pm 
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I have not done a lot of resistor checks yet in this area, it did seem some that I checked had drifted quite higher than specs. Is it still sound advice that I can check them generally in circuit, and only if the value seems way off should I then pull one lead out and recheck? Although I've gotten much better at removing parts the fragility of the PCB still makes me wish not to disturb it more than necessary especially when the original resistors would wrap the leads around and bend then amidst the solder.

P.S. The M7 group is comprised of three capacitors. 002, .005, .005... I assume the tolerance should allow .0022, .0047, .0047 in place of that?


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Tue 15, 2019 10:53 pm 
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P.S. The M7 group is comprised of three capacitors. 002, .005, .005... I assume the tolerance should allow .0022, .0047, .0047 in place of that?

yes this should be ok.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Wed 16, 2019 12:30 am 
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MattPilz wrote:
I have not done a lot of resistor checks yet in this area, it did seem some that I checked had drifted quite higher than specs. Is it still sound advice that I can check them generally in circuit, and only if the value seems way off should I then pull one lead out and recheck? Although I've gotten much better at removing parts the fragility of the PCB still makes me wish not to disturb it more than necessary especially when the original resistors would wrap the leads around and bend then amidst the solder.


You need to develop an eye for looking at the schematic and figuring out where measuring resistors in circuit may give you a incorrect reading. Remember resistance is measured using DC, because of that capacitors smaller than about 1uf have no effect, they look like an open circuit. Also except for the ends of the heater, tubes will look like an open circuit, remember you are measuring without power.
Looking at the vertical circuit around V7 and V13, you could check R4, R6, R79, R80, R81, R82, R83, R84 and R86 without a problem. R5 and R85 are connected to C2C and C4 so the reading will change as the capacitor charge but the measurements should settle at the right value. Now if any of the small capacitors have a lot of leakage at low voltage they will throw the readings off, making them low.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Wed 16, 2019 4:07 am 
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since the couplate is just caps no resistors in there provided none of the caps are in paralel with eachother you should be able to use your sprague cap tester to check them. if ok it will save a little work making a new one. just a thought.

the way i was taught to mesure a resistor in circuit if the value is off disconect one leg of the resistor and check again. if it reads in tolerance it is fine. one quick way to check resistors is the resistance measurements in the sams from tube pins to ground. or the voltage measurments. if they come out within tolerance the associated components should be fine. if one particular pin is off only the components attached to that pin need checking. this is standard troubleshooting procedure. remember time is money and a shop did not have time to check every resistor in the tv so these proceedures were developed to save time but are efective. by components i mean resistors caps coils etc attached to that one pin.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Wed 16, 2019 4:29 am 
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M7 Follow-up - I created a DIY version of this with new components on a perforated circuit board (three resistors and three caps) but soldering it on still does not improve the lack of vertical hold. I will keep checking resistance and voltage to see if anything still stands out, and will also try a regular broadcast via converter box to rule that out. But it is bizarre that whether or not M7 (old or new) is in place has no perceived difference in the vertical problem - I can still get a fine picture just not locked in vertically.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Wed 16, 2019 4:56 am 
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if there is no difference in performance between the origional and new m7 the origional is probably fine and can be soldered back in place.

with m7 disconnected the symptom should be a picture that constantly rolls vertically and cant be stopped. depending where m7 is in the circuit you may also loose vertical hight all together.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Wed 16, 2019 6:00 am 
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I put the original M7 back in again for now. I then tested voltage of V6... Pin 9 stands out (75V vs. 90V), and possibly Pin 2 (3.92V vs. 5.5V). Also I tried a regular cable hook up with network television and the same symptoms occur with the vertical scrolling that varies by darkness/lightness on screen. Also the buzzing in the speaker is definitely quite prominent when the screen has a lot of white on it so that's still some side issue but definitely not to the unusable state as the video is.

Pins 1-4 (Sync Phase Inv)
Pin 1: Spec - 10V | Actual - 10V
Pin 2: Spec - 5.5V | Actual - 3.92V
Pin 3: Spec - 240V | Actual - 241V
Pin 4: Spec - X (Ground) | Actual - X (Ground)

Pins 5-9 (Video Output)
Pin 5: Spec - Ground | Actual - Ground
Pin 6: Spec - 1.3V | Actual - 1.45V
Pin 7: Spec - -0.5V | Actual - -0.67V
Pin 8: Spec - 115V | Actual - 113V
Pin 9: Spec - 90V | Actual - 75V

Quote:
with m7 disconnected the symptom should be a picture that constantly rolls vertically and cant be stopped. depending where m7 is in the circuit you may also loose vertical hight all together.

After removing the one I made and trying again I can confirm I lost all sync so it looked just like garbled mess (but you could still see the black bar between frames scrolling slowly down). So not sure why it seemed there was still good image last time but without M7 you are correct it is nothing decipherable. With M7 in the image is fine but sync still a problem.


Last edited by MattPilz on Oct Wed 16, 2019 4:27 pm, edited 1 time in total.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Wed 16, 2019 11:55 am 
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all voltages for the video output within 20 percent tolerance. i dont see any problems there.

sync phase inverter pin 2 is out of 20 percent tolerance by about 12 volts and individual components should be tested that are attached to pin 2.

one question about the voltage on pin 6 of the video output you list -145. i assume you mean -1.45. if it is actually -145 that is a problem too.

i would say check r74,r77,r78 c69 r89 r90. since c61 is the coupleing cap to the previous tube and if that was leaky it would make the grid more positive i would say c61 is fine. the grid would read above 5.5 volts not lower if c61 was bad. .


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Wed 16, 2019 4:17 pm 
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MattPilz wrote:


After removing the one I made and trying again I can confirm I lost all sync so it looked just like garbled mess (but you could still see the black bar between frames scrolling slowly down). So not sure why it seemed there was still good image last time but without M7 you are correct it is nothing decipherable. With M7 in the image is fine but sync still a problem.

Well if the picture was completely scrambled that sounds like the horizontal lost sync also.

As far as the voltages on the video output section are concerned, the setting of the Contrast control would effect them.
Too bad about the M7 not fixing the problem. This kind of indicates that there isn't much sync signal there for M7 to pass. You could use your scope to confirm that or even have checked before making a new M7.
Unlike in the Vert Oscillator/Output area, some of the resistors that Thomas13202 mentioned will not be able to be measure correctly with out disconnecting at least one. Those would be R74, R77 and R78. You could disconnect one end of any of the three and then be able to measure all three.

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Wed 16, 2019 4:45 pm 
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Quote:
one question about the voltage on pin 6 of the video output you list -145. i assume you mean -1.45.

Yes, typo only. Was 1.45V.

One thing I just noticed is that when I first got picture again after the flyback and horiz. Osc. were eplaced (back in August and page 4 of thread), the video didnt exhibit this rolling behavior at all. I recorded two videos at the time while playing a very high contrast movie scene of blacks and whites and cut scenes and never once did it lose vertical hold. It had other linearity issues but no roll seen now.

https://youtu.be/J8f9n30-bZ8

I believe it was after that point I changed out many of the caps including the canned ones so I will try to backtrack the changes I made in between this verical hold issue. I kept bits of notes and a progress journal plus this thread so maybe I can track it down better.

Edit - Based on my progress posts here I already noted the vertical hold issue by august 31 in the same update I mentioned I had replaced the caps on the sync circuit and video IF boards, but hadn't changed the canned electrolytics yet. I wish I had more carefully checked after each cap replacement since as others mentioned here it would certainly had been easier to troubleshoot.

I will have to double check that no cap was inadvertently connected to wrong point and more carefully check for any possible trace lifts.


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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Thu 17, 2019 3:50 am 
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A little logical thinking here. The signal on the plate of the sync tube has to get to the grid of the vertical oscillator. What besides M7 is between those two points?

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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Thu 17, 2019 4:59 am 
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Tonight I checked over the capacitors that I had record of replacing around the time I first noticed the vertical hold problem. As I went along I also replaced some 400V ones with 630V now that I have a surplus of them. The vertical hold problem was not altered by any of it.

Audio Buzz - I found that removing C57 on the sound board fully clears up the loud audio buzz but then there is no amplification, so it is very low volume but sounds perfectly clear including up close to the speaker and with the volume control at max. That led me to start checking resistors on the sound board that connected to C57. I replaced the two higher precision, higher wattage (2W 5%) 2M & 1.6M resistors with new ones, but the buzz still persists whenever C57 is attached. I checked a few others and they were still within spec. No other capacitor on the sound board altered the buzz noise, just C57. The buzzing is noticeable with the volume at 0% with or without a signal attached. Attached are the audio-related circuits FYI.

Edit - Update: When I checked pin 1 of V10 (AF Amplifier) with multimeter probe the buzzing sound grows much louder and deeper (and even more-so if I do not have the common probe grounded). It appears the 0V region is giving off tiny voltage .001-0.004. Without a tube in no voltage is read from this pin 1 ground region. I thought maybe it was a faulty tube but tried a second of the same type (6AV6) and it exhibits the same symptom. Is it possible the socket itself has some short or fault?

Quote:
What besides M7 is between those two points?


See attached:

[V6 Plate (Sync)]



R75 (6.8K), R76 (3.3K), C68 (.001)



[M7]



C62 (.0022), R79 (220K)
R84 (100K), C67 (.001), R86 (220K)



[V7 Grid (1/2 Vert. Mult.)]


Attachments:
Sound-1.JPG
Sound-1.JPG [ 256.28 KiB | Viewed 1491 times ]
Sound-2.JPG
Sound-2.JPG [ 413.89 KiB | Viewed 1491 times ]
M7-Area.JPG
M7-Area.JPG [ 161.58 KiB | Viewed 1491 times ]
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 Post subject: Re: 1956 Admiral Console - Some general technical questions
PostPosted: Oct Thu 17, 2019 3:19 pm 
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As far as the sync signal getting from the Sync Phase Inverter plate to the grid of the Vertical Oscillator besides M7 there is only C62, but I believe that has already been replaced. That is why I thought it was M7.
Since the horizontal has few sync problems, the sync for that does seem to get through the Sync Phase Inverter.
The question I have is, is the vertical sync signal at the plate of the Sync Phase Inverter? I really wish that point was looked at with a scope.
It could also be that the Vertical Oscillator (Multivibrator) has a problem reacting to the sync pulse. Resistors or capacitors might cause that problem.

The volume control is a bit unusual in that it does not have one end connected to ground. Instead of the volume control selecting a percentage of the output of the sound detector, it varies the amount of resistance inline to the sound amplifier.
Matt, is the metal case of the volume control grounded? It probably needs to be a shield for the signal. The hum could be getting into the audio amplifier stage from the area feeding it (volume control area and audio detector area) or from the power supply ripple. If you put a scope on the power supply you could see if there is too much ripple. Another test would be putting a short across C52 or point "D" to ground. It takes very little signal at the input of the sound amplifier for you to hear hum. Don't forget that your body is an antenna for hum.

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