a real challange?

[Yamamaya42]

Originally Posted by Kevin Kuehn

From either pin 1 or 2 of the rf amp to the red B+wire you should read around 3,500 ohms if R1, 2, 4, 11 were close to as marked. R1, R2 are paralleled by the tuner switch and those are in series with R4, R11. It's possible your meter is charging some cap, but I'm not seeing it at first glance. Or maybe the meters voltage is setting up an oscillation, who knows. All those tuning coils should read relatively low DC resistance compared to the higher total resistance. Anyhow it appears you now have a decent B+ getting to those plates, so I'm getting a little lost with the ups and downs.

I'm not sure if its a tuner issue still or not, there is still snow in the pic, the 150 ohm resistors DO seem to be a bit off, but i don't know how much it is affecting anything in there.

I could try re-checking the plate resistance with a non digital meter, I think i have one, not sure.
the tubes in the tuner ARE new.

could this all be IF? or both, perhaps no way to tell really :/

[Yamamaya42]

Things I'm wondering about...

that mystery 680k pullup to 275v that was never hooked up, should it be tried now perhaps, because it does have an effect on the IF/tuner.

The 2 150 ohm resistors (measured from 5-6 on rf amp ) was collectively 438 ohms, which is quite a bit over 30%, (46%, from what I can tell.) I don't know which one is bad (most likely both ) and what the loss of possible balance is doing to the amp circuit, I can only speculate on how it really works right now.

I do have a mostly working analog multimeter, and will try to measure the plate resistance again on the RF amp.

Plan to do...
Remove the run of balanced 300 ohm wire running from the back of set to tuner and solder channel master cm-94444 balun directly into tuner, grounding 75 ohm to chassis via cap.

Replace peaking coils & video output tube (have 2 out of 5 ordered so far ) , hoping this will stop video smear.

Add contrast mod as mentioned before.

I have a new digital rf signal generator & LCR meter, no idea when they will get here, will re-try alignment when it comes, with exact freq set (I hope) and amplitude control.
Will also be able to test the old coils.

And after all that, I still can't get a clear pic w/o snow / RFI, perhaps convert to A/V input.

[Yamamaya42]

Originally Posted by Kevin Kuehn

From either pin 1 or 2 of the rf amp to the red B+wire you should read around 3,500 ohms if R1, 2, 4, 11 were close to as marked. R1, R2 are paralleled by the tuner switch and those are in series with R4, R11. It's possible your meter is charging some cap, but I'm not seeing it at first glance. Or maybe the meters voltage is setting up an oscillation, who knows. All those tuning coils should read relatively low DC resistance compared to the higher total resistance. Anyhow it appears you now have a decent B+ getting to those plates, so I'm getting a little lost with the ups and downs.

found 2 meters that worked well, my 16 year old fluke 77, says it's 4.39k so did the very old Micronta 22-220, but the no-name brands gave me crap, but the fluke did give the same reading as the crap ones did for the resistors on the grids. about 438 ohms.

[Kevin Kuehn]

Last I heard you said your tuner tube pin voltages were checking OK per Sams, so any drifted resistors really aren't too concerning to me. But I'm only one persons opinion. To me the bigger issue is you really don't have any good method to check signal strength or substitute a known good signal at various points in your set. Personally I like the convenience of a B&K 1077B Analyst. With one you can substitute a Video IF signal and compare that picture with with what you get connecting to the antenna. Basically you'll be able to substitute signals starting at the CRT and work your way all the way back to the antenna. The catch is these units may also need some repairs made to them. But they are relatively common place and also quite inexpensive if you can find one from some place local to you. Quite literally no one needs them today other that a handful of us hobbyists, so there's no good reason they should be anything but dirt cheap, or even free for shipping.

[Yamamaya42]

Originally Posted by Kevin Kuehn

Last I heard you said your tuner tube pin voltages were checking OK per Sams, so any drifted resistors really aren't too concerning to me. But I'm only one persons opinion. To me the bigger issue is you really don't have any good method to check signal strength or substitute a known good signal at various points in your set. Personally I like the convenience of a B&K 1077B Analyst. With one you can substitute a Video IF signal and compare that picture with with what you get connecting to the antenna. Basically you'll be able to substitute signals starting at the CRT and work your way all the way back to the antenna. The catch is these units may also need some repairs made to them. But they are relatively common place and also quite inexpensive if you can find one from some place local to you. Quite literally no one needs them today other that a handful of us hobbyists, so there's no good reason they should be anything but dirt cheap, or even free for shipping.

looks up " B&K 1077B Analyst"
I remember that thing!
I used to work in a TV repair shop late 90s and the owner had one, it was not used much , but I DO remember the CRT inside in front of the weird pick up tube that you put cells in front of for display output.

and there are some on e-bay
perhaps when I get my tax refund


and true about the tuner, I'm pretty sure that trying to replace anything in it would do more harm than good.
There Used to be someone within 50-70 miles from here who fixed/ rebuilt them, but they have not been heard from in some time. "quality tuner service" out of Longview, TX.

[Kevin Kuehn]

Yeah ebay unfortunately is probably about the most inflated place you could get one. Should be $20 maybe 50 tops for a very nice looking one. You really should make sure you get at least the target slide with it. Otherwise the only cable you'll need is a BNC to clip leads. Shipping too is a deal killer now days on test gear. Ask around if there was anyone in your area that used to service TV's. Post a wanted add on FB marketplace if you have an account. Seems to be the latest and greatest place to sell old stuff.

[Yamamaya42]

the latest test...

https://www.youtube.com/watch?v=dkHebH7xepU

hooked channel master cm-94444 Balun directly to tuner ( soldered)
added ext RF amp, +15 db

still waiting for other peaking coils and Pot to add the contrast mod.

there is still a slight bit of snow in pic .

but is looking better.

[Yamamaya42]

I'm hoping that once i hook the 12lp4 up, that the retrace lines will go away, I'm not really sure how they got blanking to work in this thing.

but since I am using a "test CRT" and it's not quite right, i guess that is why the lines are there for now.

[bandersen]

Most early TVs didn't have any retrace blanking. Ideally, they are watched in a dimly lit room and you adjust the brightness and contrast so they are not visible.

[Yamamaya42]

Originally Posted by bandersen

Most early TVs didn't have any retrace blanking. Ideally, they are watched in a dimly lit room and you adjust the brightness and contrast so they are not visible.

It's a shame that no one has come up with a blanking mod for it over the years.

[Kevin Kuehn]

Originally Posted by Yamamaya42

the latest test...

https://www.youtube.com/watch?v=dkHebH7xepU

hooked channel master cm-94444 Balun directly to tuner ( soldered)
added ext RF amp, +15 db

still waiting for other peaking coils and Pot to add the contrast mod.

there is still a slight bit of snow in pic .

but is looking better.

That actually looks quite respectable. Are you using a DVD player, and have you tried any other signal source? You've definitely come a long way with that TV.

[Yamamaya42]

Originally Posted by Kevin Kuehn

That actually looks quite respectable. Are you using a DVD player, and have you tried any other signal source? You've definitely come a long way with that TV.

Yes, it is a DVD player, a cheap one I got a $20 piece of garbage, which I got as a source for working on my CTC-16XL, went ultra cheap so if it was taken out by the HV or whatever, I would not lose anything.
I made the DVDs myself from videos I had on my system so it would be macrovision free.


I put in the contrast mod today, and it does work, not as dramatically as it did in the color set I took it from but it works, most likely cause the CTC-16 has 10v on the cathode at that point, and this thing has about 3v, so perhaps I will put in a larger cap than 50mfd.

I'm hoping that the other 3 peaking coils show up this week, shipped 4/14 from Canada, this pandemic has slowed all mail down

I see that at least the cheap LCR meter I sent for is in the country now, and may be here this week.

no idea when the digital RF generator will show up, when it does I can hopefully clear up that last bit of snow.

[Kevin Kuehn]

Well if you haven't already try another RF signal source. It would be something if your snow issues turned out to be caused by a cheap DVD player.

[Yamamaya42]

Originally Posted by Kevin Kuehn

Well if you haven't already try another RF signal source. It would be something if your snow issues turned out to be caused by a cheap DVD player.

the DVD player itself has no RF modulator, they stopped putting those in years ago when things switched over to digital.

got this

https://tinyurl.com/yaez4lm4

hooked into an RF amp to the TV.

[Kevin Kuehn]

Originally Posted by Yamamaya42

It's a shame that no one has come up with a blanking mod for it over the years.

Try this:

1. Place a 47k resistor between pin 11(cathode) of the CRT and ground.

2. Connect a .05uf, 630v cap from pin 3 and 4(plate) of the 6K6 vertical output
to pin 11(cathode) of the CRT.

Basically you need a positive going vert deflection pulse at the CRT cathode in order to blank the picture during vertical retrace.