* Failed OPOST 000A 12V over voltage error
* Compare and verify results with gold card - run command 'pt 0a` at
nominal and under voltage, should equal passed at nom and fai 11211s1823l led at under if ok.
* Matched code to page 21 of the schematics from Error Code spreadsheet - Toggle
monitor 12V over .
* Measured pins on U33, see immediate fault at pin 2, this line is high (3.3V) when it
should be low : verified on gold card.
* Checked input voltages to U33, pin 4 has reading 0.03v of a difference compared
with gold card. (1.25 -1.28V measured : bad, 1.28 -1.31V measured : good)
* Traced faulty line back to R169/R170, these were measured with R169 out of
tolerance.
* Part replaced and retested, passed.
* In this instance, there were a lot of fails connected with under/over voltage
monitoring relating to the same faulty part which is used 4 times in the voltage
monitoring circuitry, therefore a decision was made to replace all four parts at once
in case of future failure (time saving).
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