[sebhc] Re: H8 data record format

Dave Dunfield dave04a at dunfield.com
Fri May 7 05:18:31 CDT 2004


>> 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?

#1 - Wear eye protection. This is VERY IMPORTANT.
     I've had a power supply cap short, causing a regulator to explode which
     buried part of the casing in the wall!!!

- Visual inspection, especially look for leaking, deformed or discolored capacitors.

- Test power supply alone first. Remove all logic boards or disconnect the power
  supply DC leads. Switchers may require a small load to operate correctly.

- Current limit the supply. For small linear supplies, running through a 100w light
  bulb initially is a good idea. This works ok for small switchers too, but be careful
  that the supply operates correctly on reduced voltage.

- Use a variac to bring the supply voltage up SLOWLY - for very old long-out of service
  equipment, take a good long time, allowing the capacitors to reform.
  Don't do this for switchers or if the power supply is not completely disconnected from
  the rest of the system.
  Monitor the output as you do this and confirm that it is coming up as expected.
  Monitor voltage and waveform across filter caps to insure that they are not shorted or
  open.

- Check power supply voltages.

- Power the logic boards one at a time - If the system is small enough, continue to use
  the 100w light bulb in the AC power loop - use fuses on the DC side (you will have to
  estimate power requirements for the boards).
  ** WEAR EYE PROTECTION **

Regards,
-- 
dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.
                http://www.parse.com/~ddunfield/museum/index.html

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