A rare site, an RCA CTC17x that's never had the tuner soldered

[radiotvnut]

The other day, a lady at a local church contacted me on Facebook and offered me 4 TVs for free that didn't sell in their last rummage sale. The sets were a 20" RCA CTC176 from 1996, a 25" Sanyo from 2003, a 19" Sanyo from 1998, and a 19" Samsung from 2000.

All worked, but I decided to open them and so some preventative maintenance. On the two Sanyo sets, I replaced a few capacitors that were known to give trouble and re-soldered some things.

I did the same thing to the Samsung and as I was putting it back together, I wasn't paying attention to what I was doing, the HV lead got tangled up on the convergence rings, I slid the chassis in too forcefully, and the board cracked around the flyback transformer. I'm trying to decide it I want to bother with it or salvage it for parts (I believe the tube will fit in that Zenith I got a couple of weeks ago).

Last, we have the RCA. It worked, but tapping on the tuner shield made it act up. So, I opened it and nobody has every soldered on it before. It looks like a low hours set, so I soldered the tuner ground connections, and it seems to be working fine.

The very first CTC177 I saw was an LXI-branded Sears set from 1992, and it was just out of warranty. I recall thinking, "what a piece of junk this is." After that, I fixed lots of tuner ground issues in those RCAs, but I don't know why it took them until the later run of the CTC203 to realize that maybe they should go back to a separate tuner. If it wasn't for those tuner issues, those CTC17x series sets would have been very reliable. I don't recall seeing very many bad tubes or flyback transformers in those sets.

[dieseljeep]

When I first saw this thread, I never knew about problems with the CTC17X.
The CTC177X was a different story! Years ago, when I worked on the first one, I soldered all the grounds and IIRC the seam on the can. I don't remember having one come back. As I understand it can even corrupt the E-prom. They used to sell re-programmed E-proms.
As I understand, RCA picked up the tab to repair some of these sets.
Around that time, GE dumped RCA to TCE.

[JohnCT]

I repaired several thousand of the 17X series over the years with the "TOB" - tuner-on-board as Thomson called the design.

The problem wasn't the tuner design as much as the implementation. If RCA/Thomson/TCE had added ground *wires* instead of relying strictly on the tuner wrap to provide ground structure, the tuner issues wouldn't exist. It was the constant expansion and contraction of the large tuner wrap that caused the brittle solder to crack.

A lot of companies had similar issues with the lead free solder even in can tuners. I did tons of Sony tuners and tuner/IF blocks for basically the same issue. The only difference is that the bad solder didn't interrupt the ground structure for the rest of the TV so it didn't corrupt the eeproms in Sony TVs.

Back when they first started appearing in the shop (in warranty), I would add ground wires and that fixed them permanently. Later, when I was doing 10 of these chassis a day, it was far too time consuming. What I did on those later jobs was to scratch the foil resist back around the tuner ground edges to expand the solderable lands. With some liquid flux, lead solder, and a hot tip, I would lay in a good bead of solder. Wash down with a can of Flux Off and I wouldn't see those come back for at 5 years minimum and most of them never.

RCA provided free of charge to ASCs a revision "kit" of some paste flux and a small quantity of eutectic solder as a "revision". This was "required", so periodically, I'd order a bunch of these kits to think we were following the "goldenrod" service bulletin. The solder was useless for anything so when the envelope from Thomson showed up with that kit I'd just toss them, but Thomson thought by ordering them we were using them...

Hardwiring though is the only permanent fix.

John

[JohnCT]

Originally Posted by dieseljeep

I don't remember having one come back. As I understand it can even corrupt the E-prom. They used to sell re-programmed E-proms.

They absolutely corrupted the eeproms. The eeproms themselves never failed, they'd just get scrambled. If it was just the alignment data points, we'd just realign the chassis (easy). Sometimes, even the menu "templates" would get glitched - sometimes pages were missing or incomplete. On those, I'd just put in a new eeprom and align - in retrospect, I should have bought an eeprom fixture and just reflashed them..

There were a lot of companies selling preprogrammed eeproms, but of course, there's no such thing in an analog chassis. One of those eeproms would get the TV running of sorts, but the chassis required a complete alignment, particularly if the TV was used on an antenna system (the tuner alignment data was stored in the eeprom).

John

[dieseljeep]

The last one I worked on was about the mid-90's. I just did what I noted in my first entry! I never heard anything more about it. Maybe, the owners just gave up on it! Two were RCA and one was an LXI.
I quit repairing TV's on a regular basis in 1988, but I would take one in every so often, but I would tell the owner, "I make no promises".