1949 9PC41 projection set

[Radiotronman]

I'm considering restoring my 1949 RCA projection set this winter after the GE 810. Has anyone restored one of these lately? My conical mirror and picture tube are in good condition. Anything I need to know or look for?

[hi_volt]

The high voltage chassis has a tripler. Make sure that you thoroughly clean the high voltage area to ensure no arc-over. Also, the 5TP4 runs at 26-27KV, so it can produce x-rays. Run it with the tube inside the bucket.

I see from your picture that you have the remote. Very nice. I was able to recently score a correct remote for mine.

[tvdude1]

I picked up one of these monsters 20 years ago from a collector who had passed away. It was never sold and is brand new on the pallet. Knobs and paper work are not installed ans stapled in a sealed bag in the cabinet. The tubes have cardboard protectors over them and the remote and the yoke are also in sealed RCA boxes. It must of been all set up by the service tech when delivered.

[ChrisW6ATV]

Steve Pielock restored one of these or a similar set a couple of years ago or so, and had some good descriptions either here or on the Antique Radio Forum. It would be worthwhile to find his discussions. His forum name is "pielock" if I remember right.

[Eric H]

I've restored the chassis of one but still working on the cabinet.

It's basically the same as any TV except I'll echo what Hi_Volt said, clean the HV section immaculately or it will arc and sizzle, and of course the X-Ray danger and the 27,000 volts is nothing to get careless with.

While i was working on mine I disabled the Tripler and just ran it off the first HV rectifier tube with a normal 5AXP4 test CRT, that way you aren't exposed to X-Rays or major HV while poking around.

[Radiotronman]

Thought I'd share a picture of the horizontal deflection chassis.

[Electronic M]

IIRC these sets have HV regulation issues which most objectionably manifests it's self as focus change with scene content.....One member found a solution which was to disable the tube tripler and use a SS tripler from a 70's set.

[Radiotronman]

Interesting concept. I'd like to see details on that.

[Kevin Kuehn]

Here's Eric's restore thread where Tom Albrecht and TV Engineer chime in on the HV sage/focus issues. At the end of this thread Tom posts a link to another thread where he made additional tweaks to his set. In the end it's a very impressive performer.

http://www.videokarma.org/showthread.php?t=248752

[decojoe67]

Very cool set with the original remote. I know an old-time repairman who'll work on any vintage TV's except the projection sets. I would imagine they're a bit more involved than typical TV's.

[Radiotronman]

Here is a picture of the bottom of the horizontal deflection chassis. I'll start recapping with capacitors I have on hand.

[Radiotronman]

It didn't post the picture on my last comment. So far there's not nearly as many caps as I thought there would be. I like that there are multiple chassis. Makes it more manageable and less overwhelming. I ordered the remaining caps for my GE 810 and I'll probably get into this set after Christmas. I'll begin replacing parts with what I have and begin cleaning and testing all of tubes. I'm looking forward to getting this big screen lit up! I have the original RCA device data, thanks to a fellow collector.

[Radiotronman]

Look at the size of the transformers used on this low voltage power supply! This set uses 41 tubes whereas the philco projection set of this era only used I think around 25. Why such a difference?

[Electronic M]

Originally Posted by Radiotronman

Look at the size of the transformers used on this low voltage power supply! This set uses 41 tubes whereas the philco projection set of this era only used I think around 25. Why such a difference?

RCA and Dumont in the early post-war were trying to show off what TV could do so they tended to over engineer their chassis. It was not going to market if it had JUST enough to work properly, it had to have as much stability and performance as it could. RCA also was allergic to stuff the did not hold the patent to like the tube count reducing inter-carrier audio (IIRC they were the last to adopt it).

Look at a 630 chassis 10" table set....About 40 tubes in those too.

[dtvmcdonald]

Oh just put 110 or so 1N5388s in series across the CRT and be done with it. LEave the DC restorer in. 1N5388s are cheap.