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Is it easy to replace a Quadra 650's PSU?

sardaukar

New member
I recently got a Quadra 650 and I'm super happy with it, but either the Quadra's PSU or the monitor's (an AppleVision that wobbles a bit at the top and bottom) seem to be tripping my home's circuit breakers, even when they're off. They're both plugged into sockets, I don't have the pass-through power cable for the monitor.

Is it easy to mod an SFX PSU to fit in the Quadra? I'd like to do that first, to future-proof it and rule out the Quadra being the problem. Fixing the AppleVision seems harder.

Thanks for any pointers!
 

Byrd

Well-known member
Hi sardaukar,

I wouldn't say it's easy as some Mac ATX conversions, you will need to hack up the PSU connector and potentially wire up a small circuit to support software power on.


... I'd recap what you have first

JB
 

mg.man

Well-known member
...seem to be tripping my home's circuit breakers, even when they're off.
That's most likely a failing "filter" capacitor that sits across the LIVE and GND wires. In the realy old Macs, these were RIFA (paper? cased in epoxy?) and in extreme cases could give way emitting TONS of acrid smoke. Sometimes (when they "went" but didn't short) the Mac would happily keep running. Here's some pics of one that did just that...
20200424_153026.jpg
20200424_152940.jpg

Your 650 or AV probably has a failing one - could be a RIFA or likely a more modern equivalent. Should be a Y? or X? class - someone here may know.

As a test to determine the likely culprit, you could just leave one powered-on overnight. That said, if the culprit is a RIFA, and it decides to go... you may have more to deal with than just a tripped breaker... 🤔 Probably worth having someone open them up and have a look.
 

sardaukar

New member
Thanks for the replies!

I noticed the monitor had flickering on the bottom or top fourth sometimes, so I'm hoping it's the monitor. Bought one of those DB15- to VGA adapters with DIP switches and will buy a VGA CRT (much easier to find) if it turns out it in fact is the monitor that has the faulty PSU.

So far I've had the Quadra plugged in (but off) for half a day and no breakers going off.
 

joshc

Well-known member
The 650 PSU is shared with the IIci, IIcx, P600, IIvx, IIvi, 7100, Q700 models.

It's certainly possible, the process would be the same as converting a IIci PSU to run off an ATX PSU, see here:


I'd be happy to answer any questions about how I did mine if you want to tackle it yourself. There are numerous benefits to doing the conversion, PC PSUs have come a long way in the past 30 years.
 

jessenator

Well-known member
I'm one of those few who doesn't mind re-capping a PSU, tbh. Unless you've got a rectifier issue, then it's new PSU time.
 

CC_333

Well-known member
I'm thinking of going through all my "big box" Macs, now that I actually found them, and may soon have to deal with PSU problems such as this, so here's what I'll do:
  • !f an original PSU is still working, then I'll consider recapping it, because I want to keep the machine it's in as close to stock condition as reasonably possible.
  • If the PSU has failed (won't power on, etc.), then I'll do an ATX conversion, because I don't want to waste my time and money finding a replacement OEM PSU, which is becoming increasingly difficult; finding ones that actually WORK reliably is particularly hard.
c
 
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