There are no electrolytic capacitors that are critical. In my
opinion, the 180uf and 250uf were picked for size and voltage
rating, not for value back in the day. A little bigger causes
no harm, and reduces the noise a bit. I choose slightly higher
voltage capacitors because they are bigger, and can dissipate
more power. They also have have lower ESR's, longer life ratings,
and higher ripple current capabilities.
No transistors or rectifiers, in the power supply, are prone to
failure. Really, the only parts that are prone to failure is the
orange, or clear sleeved electrolytic capacitors (2465 and 2465A),
and the -15V inverter filter cap (all supplies). The yellow RIFA
0.068uf caps sometimes go bad in Europe, but not the US. They are
rated 250VAC, which is ample margin, on top of the already ample
margin built into the 250VAC rating, for US 120V instruments.
I do a complete recap because it is a pain to remove the supply,
and my customers would rather not be subject to that pain...
I've done it so many times, I don't notice the pain anymore.
-Chuck Harris
Jean-Paul wrote:
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Dear Chuck:
Many thanks you are again the expert!
1/ Any tips on removal of the PSU for a novice? I have seen the teardown posts but it seems rather difficult.
2/ Some posts mention a 100 uF cap that must be exactly 100 uF, yet lytics are normally wide tolerance, your comment?
3/ Besides recapping, are there transistors or rectifiers prone to failure?
Kind Regards,
Jon
