Admiral 17T1: Never Give Up, Never Surrender

[Winky Dink]

I am looking through notes and photos going back to 2010,and I will shortly post the history with schematics. The short story is: I bought it and it worked. The chassis had some previous modern repairs, but also had failed soldered connections, a cardboard electrolytic with goop oozing out, and other stuff. I started "fixing" it and it broke.

[Winky Dink]

This is the saga of the Admiral 17T1. I bought for $100. Took it home, hooked up a VCR, and this is what I got:
Adm 17T12 010 by H Boyars, on Flickr

Click the pics for the original photo.

I opened the chassis and saw stuff that had to fixed. Like these open solder connections:

17T12 035 by H Boyars, on Flickr

And this cardboard electrolytic:

17T12 037 by H Boyars, on Flickr

The point is that it really needed electronic restoration, which I started two years later.
Two potential problems were (1) I was using an early 19A1 schematic, and (2) The only diagnotic equipment I had was a multimeter.

Making no progress, I resorted to testing components by replacing them. Someone suggested that C37 and C39 might be problematic. Unlikely that mica caps would fail, but I went ahead and replaced them. Unfortunately, I didn't notice that they were rated 1,000 volts, so I used 630 volt caps. Here's a schematic showing the offending condensers (in yellow):

Adm 17T12 8900 by H Boyars, on Flickr

Lo and behold, the instant I turned on the power some wire insulation melted, the wax on C41 melted, and the horizontal size pot was toast. I replaced the pot, wiring, and resistor and then put the set away for six years.

I started again last year with the Wallace-Telaides schematic, tube testers, a capacitor tester, and lots of other stuff. Tested every capacitor and resistor except micas, ceramic, and tiny dogbone resistors. Checked continuity throughout the set including the resistance of every coil. And ensured that I had a good set of tubes. Even tested the picture tube on a Philco 7053 CRT tester.

Replaced everything that needed replacing, then rechecked the wiring for every component. This is what it looks like today:

Adm 17T12 5020 by H Boyars, on Flickr

For Tube TV: I'm guessing that the horizontal hold control with the slug is the transformer on top of the chassis directly over the hhold pot. If so, the slug is centered and has no screwdriver slot for other-than-factory adjustments.

Phew, that was a lot of work. I hope the links work.
Winky

[Winky Dink]

One more thing. When I restarted the project last year my biggest concern was I had errors related to using a 19A1 schematic. My first step was to invent the "Schematic Differential Too." The Rider 19A1 schematic and the Telaides 17T1 were made on the same template. I printed the Rider schematic in red on white paper and the Telaides in black on transparency film. This is how I identified differences in the schematics:
(I just learned how to embed photos that you can click to go to the original)

Adm 17T12 5000 by H Boyars, on Flickr

Hence I wired the 17T1 to be in compliance with the Telaides schematic. Except for R41.
Thanks again.
Winky

[Notimetolooz]

Hummm, C41 is across some tube filaments, hard to see how the wax could melt and the filaments did not burn out unless it was a dead short.
That doesn't explain why the horizontal size pot burned.

Are you sure you read the value on C37 and C39 right?
They look a bit small for 1000 pf, 1000V.

What do you mean "factory adjustment"?
The coil may adjust with a hex tool (non-metallic).

[Notimetolooz]

Originally Posted by Winky Dink

Hence I wired the 17T1 to be in compliance with the Telaides schematic. Except for R41.

Winky

You shouldn't put a teaser out like that.
The obvious next question would be "So how is R41 wired?".
After searching the schematics that you posted, and ignoring the ones of questionable heritage, the connection of R41 are all the same except the SAMS 19A1. That SAMS shows it connected to B+, the same source as the horizontal size pot, this indeed seems to be how your R41 is done.
The set uses what is sometimes called a "split supply" like many. The audio output stage (V4) receives B+ for power, the audio output tube is one of the tubes in the set conducts a fairly constant high current. A voltage is developed from the cathode (pin 8) that is also fairly constant, this voltage is used by several other circuits for power. The Wallace Telaides schematic shows this voltage supplies R41 not B+. B+ is much higher than the voltage from the audio output cathode.
Just to eliminate them as a source of a problem why not replace C37 and C39 with micas. Micas are available.
https://www.digikey.com/en/products/...102JO3/1918615
Expensive but maybe worth saving the torment of solving the problem.