Model 90 mystery cap - Printable Version

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+--- Thread: Model 90 mystery cap (/showthread.php?tid=2001)

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Model 90 mystery cap - mgutierres - 09-03-2009

Hello. I finally registered to the Phorum after months of lurking because I finally found a question that hasn't already been addressed here. I'm re-capping my very first Philco, a Model 90 that a friend found at a yard sale in Montana (I won't tell you what he paid for it, but it was CHEAP!).

There seems to be a mystery capacitor connected between the #18 By-Pass Condenser (3903-M) and a terminal on the speaker socket. The value is .05mfd/200v. I haven't seen this cap in any diagram or schematic, and it doesn't appear in the photo that Ron posted elsewhere of a pristine Model 90 chassis. It appears to be from the same era, judging from the paper wrapping and size, so I'm guessing it was attached by a service tech who may not have had access to Philco's secret bakelite cap contents listings.

Question: when I get to that cap, should I just not replace it, and assume that replacing the caps inside 3903-M (which specs at .01mfd) will take care of it, or should I replace the .05mfd external cap as well? What do I risk by removing that cap?

I never would have attempted this re-cap if it weren't for the Phorum and all the incredibly valuable advice I found here. I appreciate all of your collective knowledge and experience!

Thanks,

Mike

[Image: http://i326.photobucket.com/albums/k420/mrphilco/Phorum%20Stuff/IMG_4731a_zpsb7384433.jpg:original]

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Re: Model 90 mystery cap - mgutierres - 09-07-2009

Think I found my way around it, using the Rider's pages posted online. Unfortunately, when I put it all back together, I got bad squeal and BLATT above 900 khz., and decent reception below that. Coils look like they're okay, but some resistors are way off spec, so that's next. I'll let you know how that makes it sound...

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