ID-5001 barometer problem

[me (SW Bell)]

I have an ID-5001 that has performed without flaw since I built it when they
first came out. A few days ago, the barometric pressure reading became
wildly erratic, sometimes indicating swings of 3"/hour. The changes are not
jumps to another reading, but fairly smooth transitions. All other readings
are stable and seemingly correct.

I have looked over the schematic enough to see that there are a LOT of
potential problems, some of which would be hard to pin down. All I have
checked up to this point is the stability of the + and - 15 VDC, which looks
fine. You would expect this, however, in that all else looks OK.

The unit is 100% original except for the illumination circuit, which gave
out many years ago and was replaced with a simple electronic ballast circuit
that runs the tube at 100% power all the time.

Has anybody seen this problem before? Is there is "normal" or "standard"
failure that causes this to happen?

Thanks in advance!

Mike McCauley, WB5MYY
Dallas, TX

Sponsored by the City of Tempe 

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