IRIS failure point-beware paper caps!

compoobah at compoobah at
Sun Oct 16 15:52:51 CDT 2005

I took the IRIS over to Ray's to see if we could get it working and pull anything of interest off the drives, and the power supply died. If you have one of the Motorola IRISes be sure that you check out two paper caps (C7 is one of them) on the 5v rail board (on the fan side of the P/S). Had a failure in one or both that caused a (hypothesized) spike to the rectifier bridge and smoked a MOV/resistor link to ground. Fortunately there doesn't seem to be any logic damage, but watch out if you've got one of these! 
    Later research with an electronics book revealed that paper & electrolytic are the most failure-prone of the capacitors. I'm going to replace with mylar (I know they're not original, Tony, but it's a terrible job to get that P/S out, and I don't want anything to die the next time).

 Scott Quinn

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