DOM MB Diagnosis page
Board ID:
V5.0L 000589
Source:
George Chao
Symptoms:
Intermittant communications or boot problem.
Analyst(s):
G. Przybylski
Analysis Procedure(s):
While checking power supply voltages, discovered
that the 3.3V net/plane had 5V on it because of a malfunctioning U8
switching controller.
Low temperature profile 12/16/04 results:
Local coincidence loopback test fails at and below -60°C.
At -75°C, failures of the ATWD A Channel
1 baseline failure, and long memory 0 and mamory 1 tests.
800 cycles of reboot test every 2 minutes while cycling the refriger
from -55°C to +65°C
every 90 minutes; No boot failures.
Root cause:
Related to faulty U8, or U8 soldering irregularities.
Mitigation:
Touch up soldering to U8, or replace U8 recommended. (not apparently
done as of 12/17/04)
Disposition:
Not to be integrated into an optical module for in-ice or IceTop
deployment.
Any Other Information:
Traveler August 20