[Test-Equipment] Putting power to 7904 out of storage

[Larry Will]

I concur with John,

I have used the bulb option on Tek scopes and modern TV sets and I 
know other who do the same.

The Tek 7904 supply if overloaded or in trouble will appear dead but 
if you listen carefully you should hear a tic tic tic sound 
indicating repeated attempted starts.  The Tek service manual has a 
good section on troubleshooting that supply and I have removed them 
from the scope to do unloaded tests.  They should come up and deliver 
the miriad of DC voltages that they do just sitting on the 
bench.  When it works that way its time to put back in scope and see 
if any other troubles are in the mainframe or plug-is.  I look for 
obvious dead shorts on all DC busses to try and isolate any failed 
components.  Just time consuming.

Larry
w3LW

At 11:00 AM 2/2/2009, you wrote:
>IMO, bringing up a switcher on a variac is iffy. I use a line cord fixture
>with a few ordinary light bulbs (parallel connected) in series with the
>hot side. This prevents fires in case of a serious failure. On a good
>supply, they will have little impsact, except for inrush limiting.
>
>Best,
>-John
>
>
>
> > Dennis,
> > You may be right about the switching PS requiring different start-up
> > procedure.  In any case, I'd recommend monitoring the input current to
> > be sure it does not get excessive.  I have used, for decades, a
> > metered variac to power up long dormant equipmwnt; maybe even saved a
> > few power transformers.
> >
> > If you have a variable voltage DC supply, you might consider applying
> > dc to input of DUT PS filter circuit and monitoring the current as DCv
> > is increased.  This procedure will also reform long dormant
> > electrolytics. Cheers, Chase/K4AFW
>
>
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