Re: 7904 Mainframe damaged


JJ
 

Thanks. I'm plodding along following the the manual. You got me thinking
there could be a point somewhere in a path through the instrument's
grounding system that took the most stress and failed - maybe on the main
interconnect board.

Really! That's precisely how I felt: "When that thing fried and it was my
fault it was worse than if I had run over somebody's dog or something."

On Wed, Apr 11, 2018 at 9:19 PM, Jeff Urban <JURB6006@gmail.com> wrote:

On Wed, Apr 11, 2018 at 11:06 am, JJ wrote:


I was measuring a voltage on a leg of a bridge rectifier (110v) when
there
was a snap - and I realized what I had done.
Don't sweat that, it is nothing. I interpolated two plugs in a 7603 hat
dumped 130 volts on the 5 volt line. Of course it took out the horizontal
preamp output IC, one of the most unobtanium things in it.

Luckily I had a parts donor handy, and much to my surprise I got it
running again. Luckily when one thing shorts it protects the rest of the
parts on the line :-)...usually.

When that thing fried and it was my fault it was worse than if I had run
over somebody's dog or something.




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