RCA CTC 120, weird tuner issue

[MRX37]

(TL DR the iron tuning slugs in both the audio and IF sections were crumbling into dust, throwing off the inductance, and throwing off the IF alignment)


Just when I think I’ve gotten out of the vintage TV collecting habit, I get pulled back in!

https://images2.imgbox.com/11/9a/mUfexVDx_o.jpg

It’s an RCA CTC 120 console set. It’s nothing special, except, it was just two houses from where I live, it’s in pretty good cosmetic condition, and it even still has the original power cord.

I first saw this TV while making a pit stop at home, and I said to myself “I don’t need it. I don’t need it. I don’t need it!”

I mean, I have an RCA Dimensia from November 1987, just before Thomson bought them. I don’t need a Mid-Tier Colortrak from 1983 that doesn’t even have A/V inputs!

So, I left it there, went back to work figuring a scrapper would come and get it and that would be the end of that.

I got home 3 hours later, and unfortunately it was still there, and still had the power cord.

As if to underscore that I was meant to save this TV, a scrapper pulled up right as I was wrestling it into the house.


"Grandma, you need to keep the TV on Channel 3! Use this remote to find Jeopardy!"

So I let it get up to ambient temperature and plugged it in, and unfortunately, it turned right on and soon displayed a picture. You see, I was looking for justification to put it back out on the curb. But it came right on and displayed snow on the screen.

The snow on the screen was rather dim, and had a green tint. And, oh, the Black Level and Picture controls were maxed out. Yes! That’s exactly what I had hoped for! The CRT might be shot! That means I can get rid of this thing! Can’t justify keeping it if it has a bad CRT!

No wait, early 80’s RCA CRT’s tend to hold up pretty well. At least check the bias controls on the back of the set.

Unfortunately, there was plenty of room left on the drive and bias controls, and even with them turned all the way down, there was still a visible, albeit dim picture on the screen. And with the brightness cranked up, there is no color bleeding. The focus and geometry all look pretty good.

Well, shoot. It looks like the CRT is okay. Were it 10 years ago I would probably have thrown it out anyway, but these days, finding an early 80’s RCA, in this good of cosmetic shape... I’d be a fool to throw it away. Good working CRT sets are starting to get rare and to have one this nice practically handed to me…

Well I guess I’m its caretaker now.

There is one problem. The tuner is acting weird.

This was testing with my HackRF using HackTV on Channel 2:
https://images2.imgbox.com/83/7d/mX1jmwwk_o.jpg

And this was Channel 3, same power output:
https://images2.imgbox.com/83/2d/dHvKTkmi_o.jpg


To verify that it wasn't an issue with my hackRF, I tried a known good DTV converter box:
https://images2.imgbox.com/40/d2/RVx4j2NY_o.jpg

I am certain it's an issue with the tuner, because testing on UHF produces a better picture, and I was able to (once) get a crystal clear black and white image with no distortion.


Additionally, despite the worn buttons in the front, I don't think this is a very high hour set. The screws in the back haven't been taken out often, or at all before I got to it:
https://images2.imgbox.com/2d/62/h7mPfGXl_o.jpg

And the inside is weirdly clean:
https://images2.imgbox.com/1d/76/WdGENv9y_o.jpg

I mean there's some dust, but not as much as I would expect for a 40 year old television that, supposedly, has seen high usage.