[Ron Ramirez]

Tim - this should be a great thread!

The guys over at AK have stated that (what they call) the brown "dog turd" caps should always be replaced. Apparently they aren't as good as Orange Drops. Now, I have used yellow film as well as the hard case burgundy film caps from Mouser, which look like Chiclets (does anyone remember those?) to replace dog turd, clear, and EROFOL caps. I think I used all yellow film in my TA-600 and I'm quite pleased with its sound, even though the FM is Living Mono (no FM multiplex standard in 1959-60).

By "yellow film" caps, I mean the very same yellow film caps that many of us use in our vintage Philcos. I did not try to listen to my TA-600 prior to recapping it, but I have tried out a couple of my Fisher tuners prior to recapping and honestly, I can't tell the difference between old EROFOL and new yellow film or Chiclet caps. That tube Fisher sound comes shining through every time...

Ordinarily we try not to send anyone to other forums, simply because folks come here for the answers and we try to provide them when we can. In this case, however, I strongly suggest that you spend some time over at AudioKarma in the Fisher section, studying the IBAM and IBBA modifications. You should choose one or the other, and incorporate it into your 500C restore. Either circuit will allow you to properly setup the bias of the 7591A output tubes, prolonging their life. Your Fisher will thank you.

Then, of course, come back here and incorporate your added knowledge into this thread.

There are a few "dog turds" in the multiplex decoder that will require replacement. The MPX decoder also has a 1 uF electrolytic which should be replaced with a 1 uF, 350 or 400V film cap. The film cap is much larger, yes, but will last much longer.