Eico 369 restore - calling capacitor experts for help

[Sam08861]

Hi All,

For my next project, I'm looking to restore an Eico 369 sweep generator to help align my old tube radio and join his very recently restored Eico brothers. (232 VTVM and 625 tube tester both recapped and calibrated yesterday! Got both for $30 and 369 sweep generator for $25... plus probably the same in gas and tolls, lol. Fluke 8050a was $25. Man I love the prices and simplicity of old gear. Now to find a cheap oscilloscope)



So after making a 96 mile, 2 1/2 hour round trip into Brooklyn yesterday, I picket this guy up, shown with the case off and cables that came with it.



Using the parts list and schematic on BAMA, I identified these as the items needing replacement. I am not sure about c25 and c31, however.

ELECTROLYTIC
c10 2 x 20uf 450V (Can on top)
c26 10ufd 150V
c27 50ufd 150V

TUBULAR
c12 2uf 150v
c13 1uf 200v
c18 2uuf, c21 2uuf (still looking for these, lol!)
c25 .25 ufd 200V
c31 .047 ufd 600V

Here are the caps I think replacement, circled in RED and BLUE (4 electrolytic and 2 paper/foil). Question on the items in green, which are listed as 'tubular' capacitors. These don't look like anything I've seen before and not sure if they need replacing. And, I'm not smart enough to figure out how to measure these yet, lol.



Close up of c31 and c25. C31 (brown one below) has a rough body and most of the others I've seen like this before are glossy and smooth. Is this some type of mica cap or it possible that it's rusty, like the chassis that it is touching?



C25 is the glossy blue one below.



The Eico 625 also got a good workout and 3 tubes tested bad (12at7, 12au7 and 6dr7). As they were cloudy on top, broken or had hairline cracks on the base, the Eico 625 gets a pass as to usefulness!) Ordered online!

 

[Sam08861]

Ok, found those buggers, c18 and c21. What do you guys think about these as far as replacement? They are labeled ERIE NPO. The label below isn't + as in postive but reads +or- .25, I'm assuming picofarads and not percent.



I suspect that all these parts are cheap enough that I should just replace the suspect items, but some are in hard to reach places and I'm an if it ain't broke or gonna break, don't fix it kinda guy.

 

[gadget73]

NP0 are precision ceramic capacitors. Leave them alone. Don't mess with the brown ceramics either, they are probably just fine.

The turquoise cap could be a film cap of some flavor. They appear to be epoxy dipped at any rate, which is usually a sign of film. I'd be inclined to leave them alone for now.

Honestly I'd go for just replacing the electrolytic caps and adding a fuse. Chances are fair it'll work at that point. Not sure if the results will be overly useful, but it will probably do what it was supposed to do.

 

[Sam08861]

Thanks once again gadget73!

That certainly makes things easier from a soldering perspective and I'll give that a go.