Info Help..Results

[Ed Kotkiewicz]

Well, par for the course, many of the consistent contributors of this
list came out of the woodwork , yet again, to aid in the repair of a
"piece of the Green".  In this case, a dead SB-620.

The Hi-V diodes and at least one cap in the PS ckt were found to be
bad.  The Hi-V diodes were, of course, from the selenium rectifier era
and had a PIV of 1750.  I knew that I could hook multiple diodes in
series but as a retired aerospace engineer in the
Reliability/Maintainability field, I found this to be a weak solution.
Yes, a number of folks have had success with hooking two 1kv diodes in
series.  I was hoping to avoid this solution.  Two of you problem
solvers had one diode solutions.  It was kind of funny, as I had just
put down the old Mouser catalog when the (I think) best solution came
through.

Mouser has a couple of 2kv diodes, in stock, at a very reasonable cost.
I was looking at the specs trying to decide if this might be the way to
go.  The winning answer came from a frequent problem/solution
contributor.  Apparently he had used this same diode set not only in the
620 but also in repairing 630's.  He also recommended replacing to
associated Hi-V section capacitor/resistor group. (something I had
already decided to do).  It is getting harder and harder to find
hi-voltage rating caps.  In this case, the solution pointed to the
"orange drops" at AES, which I was also looking at.  I now feel like I
will be on a clear success path in fixing this "green box".

Now for a little funny sidebar to the story.  The previous owner of the
box also had the manual.  Apparently these same diodes had failed before
and I received the failed ones in a separate box along with the unit.
Whoever replaced the diodes hooked one of the cathode leads to the wrong
connection on the terminal strip and guess what.....?  It was the ground
lug!  I showed this to my  resident "Former Ham at Heath" and she shook
her head at the thought of this costly *fuse*.

So in conclusion, my hat goes off and many thanks to the many responses
and great suggestions.  No names, you all know who you are.  You are the
primary contributors to this group and I am very happy to be associated
with the group.  Without a doubt, this list provides superb, quick
solutions to those who seek assistance.  Remember, read those manuals,
keep those connections straight and enjoy the success of repaired
equipment.

Tx gang

Ed

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