a real challange?

[Yamamaya42]

OK , here we go with the bad tubes
I have no tube checker...
I have NO HV and the HV rect tube has a violent purple glow to it :/
I CAN draw a decent AC arc from the AC line out of the flyback, meaning the 1B3GT is most likely bad,
have NOT turned up to full power yet, have variac at 90%, but at this point, should not matter, tube is bad :/
horz output seems to be decent, not sure at this point.

NOT a good sign :/
https://imgur.com/z7NnpHg

[Electronic M]

Your 1B3 is gassy...It happens. Good thing is it is a cheap plentiful tube (I've got a lifetime supply of used ones). It isn't a bad idea to buy 2-5 of them. They can only accurately be tested by a working TV (as repeated comparison of best in a lot tube tester VS TV has shown me).

[Yamamaya42]

new 1b3 on the way.
https://imgur.com/XymPhnp
trying a temp one!

[Yamamaya42]

Houston... we have raster!
https://imgur.com/VUa9QRs

for the first time in over 50+ years, raster!

I suspect the HOT is also a bit weak, as may be other tubes, have not tried to tune anything in yet, i suspect that I wont be able to.

And as I am using the test CRT 8YP4, the yoke does not fit quite right, ( expected this ) so wont get full screen, but this will do fine for working out the bugs.

[Yamamaya42]

and Video, although it be crappy...
https://imgur.com/lKzthZB
https://imgur.com/OrnQXum
https://imgur.com/lFGifq9

The yolk is obviously upside down, I REALLY don't like the short wires on it.
have the IF bypassed at the moment, feeding video into grid of pin 1 of 1st video, through a cap, not sure if that was the best pace or not for it, just took a guess. or perhaps would be what they have marked as POINT A, on the SAMS be a better place? 4th pix if removed.
As I mentioned before, I have no doubt that there are other flaky tubes, like i'm sure i have to get a new horz output, as it's weak, I'm sure and has a blue glow to it.

[Kevin Kuehn]

Looking very promising. All down hill from here.

[Yamamaya42]

I got the HV rect tube today, odd that the new one has a flashed getter and the old one does not, HV is still quite low, As i suspected, the HOT is also bad. has blue glow ( not as bright as the old HV rect was), will most likely also replace damper with solid state, only $10, and will never go bad. ( i hope ) https://tinyurl.com/ss5lv2b

very likely have other weak /bad tubes. for when i feed video into 1st vdo amp, by the time it gets to the final video output it looks like crap, noisy and distorted. and since in this set, the sync is taken from the final vdo amp, its very hard to get lock in this situation.

I should also go and check every resistor in the video line now, something I did not do yet, I was HOPING they would be OK enough, foolish i guess for a 70+ year old TV, i guess that it's working as well as it is now is a sign that they are SORT of OK, but that won't be good enough to get clean video through it.

I only worry about the filter coils that are wrapped on resistors, I have no way to test or replace them if bad.

on one up note, I WAS able to tune in something, but it was VERY unstable, and i could lock in on better sound,or better picture, and to see video i hooked up a ext color monitor to output of the video det (v8a SAMS) junc of L18&L19 through a .05 cap and was able to see a pic if i tuned it JUST RIGHT, ( very hard to get it ), i even got color through it, which i did NOT expect to see.

[Yamamaya42]

As I suspected, Im finding out of tolerance resistors
Mostly the 10% ones, not seen any 5% bad yet, but 40% of the 10s are unacceptable.
Example, 470k tested @ 562k and 330 ohm tested @ 389 ohms.

[JohnCT]

Originally Posted by Yamamaya42

As I suspected, Im finding out of tolerance resistors
Mostly the 10% ones, not seen any 5% bad yet, but 40% of the 10s are unacceptable.
Example, 470k tested @ 562k and 330 ohm tested @ 389 ohms.

I don't have a ton of experience on vintage tube gear, but what I've found out is that most circuits will run just fine with well over 20% difference in resistance and capacitance values.

John

[Kevin Kuehn]

Agree about the resistors, although no harm in changing them. You should check the video peaking coils for continuity. Those are the coils in the video detector, video amp, and video output stages. Normally they have a fairly low dc resistance but sometimes go open from aging, more so if the set has been stored in a damp environment.

[Yamamaya42]

Originally Posted by Kevin Kuehn

Agree about the resistors, although no harm in changing them. You should check the video peaking coils for continuity. Those are the coils in the video detector, video amp, and video output stages. Normally they have a fairly low dc resistance but sometimes go open from aging, more so if the set has been stored in a damp environment.

it spent the years from 196x -- 1996 in a basement in Franklin PA, and the rest in a shed in central TX in a box.

[Yamamaya42]

I'm not so sure about the resistors, I mean...
https://imgur.com/WdcsiK7
this plate resistor is almost 1k too high... Orange , Orange, Red 3.30k is reading 4.23k that really has to be messing with the tube bias

[Electronic M]

I'm not surprised it passes color video passband of monochrome sets was originally 4.5MHz in late 53 they mixed color into monochrome video 3.58MHz and up. And 55 and later models started being designed to limit response over 3.5MHz. Some pre-54 sets actually had color wheel NTSC adapters connected to them with no RF/IF alignment change.

The soild state 5V4 damper may fail in your application... that part was designed for 60Hz guitar amp power supplies its diodes may not switch fast enough for horizontal rate and damper service is at the edge of voltage ratings of the tube...the solid state part may or may not be rated to handle a voltage spike that would harmlessly arc the tube.... I'd stick with a tube unless you are fine blowing the SS part to learn if it works.... Alternatively you could take the base off a dud octal tube, and spec out a diode that will handle what the circuit can supply and make your own.
The current tube in it is likely just fine. Blue glow is usually fine (stray electron bombardment of the glass), but purple/Violet is usually indicative of gas leakage.

[Yamamaya42]

Originally Posted by Electronic M

I'm not surprised it passes color video passband of monochrome sets was originally 4.5MHz in late 53 they mixed color into monochrome video 3.58MHz and up. And 55 and later models started being designed to limit response over 3.5MHz. Some pre-54 sets actually had color wheel NTSC adapters connected to them with no RF/IF alignment change.

The soild state 5V4 damper may fail in your application... that part was designed for 60Hz guitar amp power supplies its diodes may not switch fast enough for horizontal rate and damper service is at the edge of voltage ratings of the tube...the solid state part may or may not be rated to handle a voltage spike that would harmlessly arc the tube.... I'd stick with a tube unless you are fine blowing the SS part to learn if it works.... Alternatively you could take the base off a dud octal tube, and spec out a diode that will handle what the circuit can supply and make your own.
The current tube in it is likely just fine. Blue glow is usually fine (stray electron bombardment of the glass), but purple/Violet is usually indicative of gas leakage.

Well something is not right, cause as of now, I have very low HV, with the new rect tube, I can hardly get 4-5 kv, where it should be 9-10kv.
Be it caused by weak tubes, or really out of tol resistors , not sure, still looking through it for crappy resistors, and IMOH, I can't really see how it can work correctly with ones as bad as I mentioned off the video output plate that's 28.18% off 3.3k :O (not replaced yet, don't have bulk 1w ), but I'm sure I will find others like it
But I can tell that both the HOT & damper have been replaced before, as they are not RCA tubes, where as most every other one in there is, this tends to tell me that of all the tubes that were going to fail in this, they were most likely the first to go, so I tend to suspect them being a problem, but I have no way to try a substitute. So I will try to find new (well, new as I can find,) and see what happens.

[Yamamaya42]

additional, I think I see a problem already , Not confirmed yet, just looking at photos I took, cause I'm not at home to check, but R120 does not look very good... (cathode resistor of HOT), missed it before. Will check later.