Reply 20 of 39, by mkarcher
Wilius wrote on 2020-08-16, 00:17:
Despite the fact, that I already know, which chip got damaged, I still meassured for continuity. […]
Despite the fact, that I already know, which chip got damaged, I still meassured for continuity.
Here is what I meassured so far:
Power Connector 1:
+12v 1909 (with CPU board installed: 1890)
Although I most likely can not help you with your board, as I don't have a Schneider VGA AT System for reference measurement, I would like you to clarify what measurement mode you used. The "continuity test" mode is a kind of "secondary function" on most multimeters, either in the "200 Ohms" or in the "diode test" mode. Because the values you showed are without a decimal dot, I guess the values are to be read as "millivolts drop" in "diode test" mode. I also guess you put the black lead onto some kind of ground all the time, and probed the power supply and CPU board connectors with the red lead.
Confirming the guesses helps other people to reproduce your measurement and check for significant differences. I like your scientific approach of providing a lot of data to support the research what might be broken on your board, but I feel it needs even better documentation about the boundary conditions. It also might be useful to know the (coarse) current your multimeter uses in continuity test. If you happen to have a second multimeter, please connect the multimeter you used for the continuity test to the current range and report the value. I expect a test current between 1 and 10 milli ampere, so starting with the 20mA range should be fine.