[quote=Lostgallifreyan;943131]"Lee K. Gleason" wrote in
:
I am restoring a 1950 Heath kit 0-5 oscilloscope. I completely recapped it except for 5 mica mold 6800pf capacitors. I generally assume that mica capacitors don't go bad so I didn't replace these.
I was having problems with the scope so I finally removed one of them (one that is in the sweep freq selection switch) and much to my surprise it was bad and wouldn't hold voltage with my Eico 950B tester. I replaced it and scope was much improved. There are four more of these across the filament/cathode of each 6SH7 amplifier tube. I will check those out tomorrow.
Here's my question..... Would you expect these mica mold black square capacitors to go bad? All the paper capacitors in this oscilloscope were bad and leaky but that's expected after almost 60 years. Am I missing something?
Would appreciate the expert’s thoughts on these capacitors
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