[time-nuts] HP 5328 PSU nightmare...

J. Forster jfor at quik.com
Sat Sep 12 05:04:21 UTC 2009

With tube gear, one fairly good way to reform the caps is either pull the
tubes (label where they came from) or disconnect the filament supply, and
then apply B+. You do need to check the schematic to make sure you don't
overvoltage caps that would see an increased voltage w/o plate current.
Also, cathode bypass caps may never see the reforming voltage.

For solid state equipment, the light bulb thing will limit collateral
damage on simple rectifier-filter analog supplies. Switchers are more



> And vacuum tube equipment using indirectly-heated cathodes:
> http://www.cpii.com/docs/related/23/Basic%20Tube%20Design.pdf
> "Operating techniques that are proper for filamentary tubes are not
> necessarily
> correct for tubes with indirectly heated cathode emitters. In
> particular, the opera-
> tion of cathode types at reduced heater voltage can be destructive to
> the tube."
> Leigh.
> Mark Sims wrote:
>> Be very careful powering up modern equipment on variacs and with light
>> bulbs in series, etc.  You go through areas where the bias voltages, etc
>> are in  the right place to cause serious damage.  Switching supplies can
>> be particularly entertaining...
>> ----------------------------------------
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