Re: Tektronix 475

Michael W. Lynch

On Thu, Oct 1, 2020 at 04:03 PM, Eric wrote:

Do you have access to a curve tracer? If so I would put VR1374 across it and
check it at its zener voltage. It sounds like the zener is acting up when
warm. But if it is an 82V Zener it sounds WAY out of spec at 66 V.

You read my mind. Yes, I actually have both a 576 and 577. See my reply to Tom below. That "suspect" diode exhibited a "normal" zener trace then suddenly broke down and I got an almost "tunnel diode" looking trace just before the trace went straight vertical. Both the 576 and 577 showed similar results after a minute or two of testing. The 475 is sitting on the bench now and looks perfectly normal after about 30 minutes of running.

Michael Lynch
Dardanelle, AR

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