Would you shotgun 1960s replacement caps in Pilot TV-37? - Videokarma.org TV - Video

Phil Nelson · #1 10-02-2008, 05:38 PM

The previous (original) owner of my Pilot TV-37 TV replaced a number of the small caps with "maroon drops" and a couple of white ceramic caps. He retired in 1965 and the maroon drops look like the originals in my 1960-ish CTC-11, so I have been assuming that they are still reasonably reliable.

Not so sure about the three white ceramic caps that he installed. I think I read somewhere that those are simply paper caps in a ceramic shell (?).

I have replaced all of the electrolytics and a few papers that he didn't get around to, including all of the high-voltage caps. Also the multi-meg resistors associated with the HV output. Tubes all test OK, except for the 3KP4, which I can't test apart from the filament.

At this stage I have decent B+ and B-, but insufficient HV and no raster. On the upper-range channels, reception is very sensitive with great audio. Funky on lower range.

This guy did very neat work -- no J hooks -- and kept notes, so I'm inclined to leave his caps in place rather than shotgun them.

Opinions?

Phil Nelson

bgadow · #2 10-03-2008, 11:32 AM

I wouldn't touch the maroons...the ceramic tubes are iffy. I've seen a few of them spill their guts. I vote for ditching them.

I recapped my VT-71 before I really knew what I was doing. Most of the caps were replaced with ones I salvaged from 70s TV modules. It works, but some rainy day I'm going to go back over it with new caps.

radiotvnut · #3 10-03-2008, 12:12 PM

I'd consider replacing the white ceramic cased caps. I've got an early '60's Magnavox B&W that needed these caps changed to fix a vertical problem. These caps have also been known to blow up. So, yeah, I'd change them. The brown drops are probably still OK.

radiotvnut · #4 10-03-2008, 12:15 PM

And I'd also change that big yellow Mallory Plascap. I've seen those leak many times.

Phil Nelson · #5 10-03-2008, 03:49 PM

Bingo! After replacing those white ceramics and the yellow Plascap, we have a picture for the first time.

Thanks.

Phil

Sandy G · #6 10-03-2008, 08:18 PM

Awrite !! An' it's got the "right" CRT, too ! Yeah, baby ! But those l'il guys were CRUDE-About all you could say was that they DID display images & sound, & were therefore, a "Television"....But back in 1947, I guess they didn't care...

Tube Radio · #7 10-24-2008, 06:46 PM

You should run the filament of that rare CRT on a 6.3 volt transformer and sub a resistor in the heater chain in place of the CRT filament as I've read somewhere many of those tubes failed due to bad filaments caused by the surge in voltage when the TV is first turned on which is why they are so rare today.
Here's a link to one someone restored. http://www.electronixandmore.com/tel...lot/index.html

***Eric H*** · #8 10-24-2008, 07:20 PM

A good CRT, you lucky dog!

kx250rider · #9 10-25-2008, 11:51 AM

Quote:

Originally Posted by bgadow

I wouldn't touch the maroons...

I second that!!!!!! If you have them, and you really want to use them, you'll have to check them for leakage and value first with a good, FULL VOLTAGE leak checker. I wouldn't be surprised if they're worse than the original wax paper Pilot ones.

Charles

Phil Nelson · #10 10-25-2008, 03:16 PM

Quote:

Originally Posted by Tube Radio

You should run the filament of that rare CRT on a 6.3 volt transformer

Yes, I bought a small filament transformer that should fit neatly in back of the HV cage. Meanwhile, I just bring it up on a variac when I want to test it.

The HV still seems low. The picture is only viewable in a dark room, and twiddling the trimmer inside the HV cage doesn't help. I'm not quite sure where to go next. There are a couple of multi-meg resistors that I haven't replaced yet. Also a pair of 300mmf/3kv mica caps that lead to deflection plates. Time for another parts order, perhaps.

On the upper channel range, the picture is clear and stable, and the audio is excellent. Nothing but feeble audio on the lower range, but I'm not going to worry about that until I get the power supply sorted out.

How critical is the position of the little metal collar on the 1B3GT tube? I marked the tube with a Sharpie when I removed the tube for testing, and I believe I got the collar back where it was before. Of course, the TV wasn't working at the time, so who knows if the previous owner may have shifted it around.

Phil