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Old 18th Feb 2019, 4:50 pm   #40
Uncle Bulgaria
Join Date: May 2016
Location: Cornwall, UK.
Posts: 296
Default Re: Ferrograph 4A: Restoration advice needed

Originally Posted by ms660 View Post
1) A megger is down to personal preference, myself I would not use one for testing run of the mill capacitors but might use one if it was a large can paper type and I wanted to know of any electrical leakage problem.

2) 16uF for the reservoir should be ok.

3) "MICAMOLD" capacitors are notorious.

4) Suflex types have been known to go open circuit or partly open circuit (very high ESR) and sometimes short circuit if there's a high voltage across them in my experience.

1 & 2. I'm fearful of leaving one in that could overload a part that is harder to replace. However, if you agree the change in value is not too far out of spec. then I feel more comfortable bringing it up on a current limiter and checking the voltages in use. If any of the big cans are shot, I can then replace them.

3. That sounds ominous! I'm considering replacing this with an X2 type. Is that a reasonable idea, or I could lash up an RC snubber. It seems odd they didn't do this, with the quality of the rest of the construction.

4. I'll disentangle them and check for shorts as there are two conflicting opinions on how reliable these Suflex fellows are.

Here's a hint as to how the case is coming along...
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