DOM MB Diagnosis page
Board ID:
Rev 5.0 SN 0544
Source:
From STF testing crew August 3,
2004
Symptoms:
Fails Local Coincidence Loopback
tests
Falis slow ADC tests.
Analyst(s):
G. Przybylski
Analysis Procedure(s):
Using shotgun approach, replace Serial ADC U4.
Symptoms persisist.
Check all the power supplies. Discovered that the LC reference voltage
was 0V.
Subsequently discovered 0 ohms resistance from Z1, Z2 case (LC
Reference voltage node) to ground, caused by shorted bypass one
of C49, C55, C61.
Root cause:
Faulty capacitor, or solder bridge
under capacitor.
Mitigation:
Tacked 1uF capacitor back in place. Ran full STF suite with 100%
success.
Routed board to Helen for part replacement and subsequent mainstreaming
for shipment to Wisconsin.
Disposition:
This looks like a one-of-a-kind
failure mode.
Any Other Information:
Travler