On Tue, Mar 11, 2014 at 11:42:21PM +0200, Sami Jumppanen wrote:
> After fixing a number of devices by replacing capacitors only, I recommend
> you always begin with them if it's likely a power issue. Electrolytes, no
> other types. Medium sized, not the smallest or biggest (depending on the
> device, there may not be large capacitors). By the numbers: usually 470 to
> 2200 micro F and from 15 to 63 volts.
... and I generally recommend people scrap equipment that's been subjected to "re-capping" when they bring it round for me to resurrect.
I've pretty much only ever seen electrolytics fail in cheap crappy switched-mode power supplies (think Amstrad satellite receivers from the 80s and 90s). Of the rest, I've replaced maybe half a dozen electrolytics that were actually the cause of a fault and only one of them in an analogue synth.
Electrolytic capacitors just don't fail that often.
DO NOT just start ripping them out because you suspect there's some sort of fault. You'll only make matters worse.
--
Gordonjcp MM0YEQ
Message
Re: [korgpolyex] Power circuit repair.
2014-03-11 by <backshall1@...>
Totally agree with Gordon on that one. Replace only bad caps, not the good
ones, and low voltage electrolytics rarely fail. If your multimeter doesn’t have
a capacitance range, you should be able to find a cheap one that will work just
fine. Power problems on Poly-800’s that I have seen are generally due to D2
and/or Q1, except for that one machine I had where Q15 and Q16 seemed to be dead
so I ripped everything out and put in the 7805.
Don B.
From: Gordon JC Pearce
Sent: Tuesday, March 11, 2014 6:50 PM
Subject: Re: [korgpolyex] Power circuit repair.