DOM MB V5 Diagnosis
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Board ID:
V5.0L 000714
Source:
George Chao
Symptoms:
No on-all Boot failure during end of HASS (i.e. cold)
Analyst(s):
G. Przybylski
Analysis Procedure(s):
On-all OK at 25C. Loaded
CPLD. Room temperature STF OK.
Board occasionally fails reboot test during temperature
cycling 10/18
Board occasionally fails reboot test during temperature
cycling 10/20
Board occasionally fails reboot test during temperature
cycling 10/26, monitor oscillator
Replaced corning oscillator
B301538-0106 0430 with B301507-63013-0419 on 10/27/04.
Board occasionally fails reboot test during temperature
cycling 10/26, find 3.3V output reads about 2.5V
11/1; not booting. Low power. Recommend replace U8.
Corning oscillator is probably
OK. (don't RMA this part)
U8 replaced 11/8/04 by Helen. The board now survived 20
cycles of temperature shock involving
heating to 70°C and cooling with Quick Freeze spray (11/29/04; gtp).
Subsequently, no boot failures during over 500 cycles of reboot test
while sweeping the temperature between -55°C and +65°C.
Low temperature profile (from -40°C to -75°C)
results:
-45°C; -50°C; -55°C,
-60°C: ATWD A Ch2 Baseline
failure
-65°C: ATWD A Ch2 Baseline failure, and
Local Coincidence Loop-back failure
-70°C: ATWD A Ch1 & Ch2 Baseline
failure, and Local Coincidence Loop-back failure
-75°C: ATWD A Ch1 & Ch2 Baseline
failure, ATWD A Ch1 Pedestal Noise failure, and Local Coincidence
Loop-back failure
Root cause:
Possibly faulty soldering of U8, or bad U8. Unfortunately,
the soldering of U8 wasn't inspected before U8 was replaced.
Mitigation:
Replace U8
Disposition:
Test and Mainstream
Any Other Information:
Traveler September 27
Note