On Thu, 23 May 2019 20:45:09 +0200, Eremita Analogico
wrote:

I have collected an old (80s) HT 1100A multimeter that seem a clone of a
Fluke of that era.
It mount a classic 7106 A/D converter that drive driectly a LCD display.
When turned off, the display appear in good conditions, no black marks,
brownings or burning signs.
When I turn on the DMM, the display show almost all segments, except
when the display is not 00.0 (that appear like 88.8)
If I measure something that implies display to show fewer segments
(like, i.e., 11.1) the reading is ok without ghost segments.
If I reduce supply from 9V to around 4-5V, the display start to show
00.0 correctly, but with still some light ghost segments.
Replacing the 7106 with another don't eliminate the problem.
Do you think that I can try to solve?
Thanks.

The clock in the 7106 is not running. I would look at the 100pf or so
capacitor on pin 38 of the 7106 for some kind of clock oscillator
waveform:
https://datasheets.maximintegrated.com/en/ds/ICL7106-ICL7107.pdf
If there's no oscillation, and it's not one of the nearby components,
the likely culprit is a blown 7016. Replacements are available:
https://www.ebay.com/sch/i.html?_nkw=7106+a%2Fd


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Jeff Liebermann
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