[sebhc] waking up old computers

[Jack Rubin]

plus:

1) eyeball the electrolytic caps for swelling/leakage; an ESR meter is a
nice thing to have
2) use a Variac to bring up the power supply (assuming it's a vintage
linear and not a switcher)

take a look at http://www.repairfaq.org/REPAIR/ - see especially the
sections on capacitor and semiconductor testing, as well as flyback
transformers

> -----Original Message-----
> From: sebhc at sebhc.org [mailto:sebhc at sebhc.org] On Behalf Of 
> Patrick Rigney
> Sent: Thursday, May 06, 2004 9:33 PM
> To: sebhc at sebhc.org
> Subject: RE: [sebhc] Re: H8 data record format
> 
> 
> > got a pop, spark, and puff of smoke from the CPU.  I think
> > it's one of the 
> > little blue capactors 
> > [snip] 
> > Anyone have experience reviving old gear?  Mine's been boxed 
> > for over a 
> > decade.  Any precautions I should take before I try to power 
> > up another 
> > unit?
> 
> My offerings:
> 
> 1) Have a generous supply of bypass caps on hand, because you 
> WILL (do) need them.
> 
> 2) Don't lean over the machine when applying power.  Big caps 
> fail too.
> 
> 3) Have another way to cut power quickly, in case you're not 
> comfortable reaching across flaming innards to get to a 
> rear-mounted power switch.
> 
> 4) Remove boards and test the power supply separately before 
> applying power with boards in.  You can also spot check each 
> board for shorts while they're out, which isn't totally 
> deterministic since some shorts can/will occur when power is 
> first applied and the part dies at that moment.  With S-100 
> stuff I've been using a bench supply with adjustable current 
> limiting to power test boards... better than throwing the 
> weight of a chassis' high-current supply into a shorted 
> board.  You just get an over-current light rather than 
> letting the magic smoke out.  In a few cases I've also been 
> able to find bad parts quickly this way, just by setting the 
> current limit low--0.5 amp or so can warm up a shorted part 
> enough to find it with a fingertip, but not do any damage to 
> the board.
> 
> 5) A little eye protection never hurts, because you never 
> know what direction or distance those little bits are going to go.
> 
> Your experience is how two of my H-89's came to be dubbed 
> Sparky and Smokey. I have another called Shell. ;-)
> 
> Patrick
> 
> 
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