Restoration of RCA 8TS30 #C061765

[Sandy G]

I sure am jealous of youse guys who can do this type of stuff; it is QUITE beyond me.

[bandersen]

Nice job on one of my favorite sets

[ChrisW6ATV]

Thanks, Bob. Sandy, I bet if you were able to put in some time with a few books and then with some test equipment and a soldering iron, you could jump right in and make some sets work well too, especially with all of the great people here on Videokarma to help.

Regarding help... I did get the B&K 1077B hooked up and I verified the RCA's tuner works on every VHF channel the Analyst has (most but not all of the VHF ones). That also verifies that the B&K itself does still work, too. Next, I will try it on the IF and/or video circuits to try to track down this maddening flashing/gain changing problem.

[Kevin Kuehn]

Nice job getting this one going. I wouldn't mind having me one of these older RCA sets someday. They do tend to be a little scarce around here though.

[ChrisW6ATV]

Thanks, Kevin. Today, I got as far as confirming that the flicker/gain problem affects the first three IF stages, which are all connected to the contrast ("Picture") control circuit as is the tuner, and that removing the first and second IF tubes does not stop the problem from affecting the third IF. Then, a horizontal problem appeared that I found is in the B&K 1077B, so I will need to go ahead and recap/test it before further use.

[ChrisW6ATV]

I did some voltage tests and found the +135V line is too high, at +173 volts. That points to a problem with the high-power three-section resistor in the compartment by the power transformer; the 6750-ohm section may be bad. That will be my next check. The video was mostly behaving as I did the tests, and the one time I caught it, the +173V went down to +171, so it may be a separate problem from the voltage issue.

[Electronic M]

Maybe there is a mica that is intermitantly shorting.
Might be a good idea to check them with an eye type tester.

[Phil Nelson]

I don't know how similar this is to the 630TS, but the local oldtimer who aligned my 630TS advised me to replace a few mica coupling caps in the video IF, calling them notorious troublemakers.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[ChrisW6ATV]

Tom and Phil-
I will attempt to check those once I fix the 135V problem if the flashing is still there. The 8TS30 has the same chassis as a 630TS. I don't have a cap checker (other than an ESR meter for electrolytics), so I may just do a mass replacement job. The IF coupling caps are the "domino"-type ones. After all the other caps I replaced, a few more won't kill me.

[ChrisW6ATV]

Originally Posted by ChrisW6ATV

Phil, I will use your Web site for inspiration!

If I had actually RE-READ Phil's description of his 630TS restoration, I would have seen references to both of my issues. Phil replaced all of the IF coupling caps right from the start, and he had a bad two-section bleeder resistor. I found out part of the same resistor has been replaced in my 8TS30 already as well. (The replacement can be seen in the second picture in Post #11 earlier in this discussion; it is the brown resistor on an angle between the two horizontal bleeders.) That replacement is 760 ohms, not the required 1360 ohms! Yep, I bet that could cause the 135V problem.

A discussion on the Antique Radio forum here mentions the coupling caps as well, and also the two caps on the AC input pins. So, I have my shopping list: Five 270pF 500V micas, a 1360 ohm 15-20 watt resistor, and two new AC line caps that I think I already have.

[ChrisW6ATV]

Five micas and a 25W resistor installed, and I have a solid, stable picture. Next, I used some Restor-A-Finish on the cabinet and it looks pretty good. The finish is "alligatored", though, and the Howard's did not fix that; maybe if I used 0000 steel wool rather than cheese cloth I could get the extra effect needed. I can see the light at the end of the tunnel, and it is not a fire truck with a burned-out headlight.

[ChrisW6ATV]

Here are some pictures of the 8TS30 reassembled. I had to reposition the focus coil and of course install the ion trap, and all of the controls behave just as they should. The only remaining work is to finish gutting and reattaching the cut-off electrolytic cans, and I need to find a correct channel-selector knob. (The one I am using is from an 8T241; it is similar but not exact.)

[Phil Nelson]

Looking good -- nice job! The finish doesn't look bad to me, at least in these photos. I have never minded a little alligatoring, if the color's reasonably even and the surface isn't flaking off.

An experienced refinisher could probably re-flow your alligatored finish smooth again. That goes beyond my skill level. My few attempts at re-flowing ended up looking more like half-hearted stripping.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html