Reply 20 of 24, by raymangold
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wrote:I had recapped some of my 486 boards with Panasonic FM FR series caps, but was not needed. The ESR digital meter gave a really g […]
I had recapped some of my 486 boards with Panasonic FM FR series caps, but was not needed.
The ESR digital meter gave a really good ESR value for some 25yr old caps, so there was no need to change them in the end. probably the small 10uF ones are the ones that need most care, since they can run out of spec easily and give you a bad behaving mobo.
I would only replace the whole board caps when i see one bad cap bulging or leaking (smelly) or when it runs like shit.
My old Asus TX97E was ok till last year, and when i picked it up from the attic last year all caps were bulging and showing crap like older Socket A mobo's did, so i replaced all with good low ESR Sanyo caps, the shiny green caps look great. and there are only like 8-10 pcs of 1000uF caps on older boards.
When you're testing capacitors, make sure they're removed beforehand-- you can't reliably test ESR of a capacitor while it's in a circuit (at which point it's probably best to just replace it). Capacitors can start leaking from their bungs once they hit 20+ years old-- the rubber bottom can start to disintegrate.
Typically you don't need to use low-ESR capacitors on vintage computers. They are fine with higher ESR as their VRMs aren't as stressed out like modern computers. Low-ESR electrolytics are less robust.