A whitening chassis at EX seemed to have died on the last Tuesday. This should be fixed.

• SN: S1101631
• location: U5 at EX field rack

All four segments of both in-vac IR QPDs (ASC-X_TR_A and _B) had been reading some bogus values since approximately 7 pm of 7th of October in PDT. Dave and I looked at the reboot logs and confirmed that no software activities were performed since 3-ish pm in this particular day. We suspected some analog issue and therefore I went down to EX to check out the circuits. The AA chassis seemed to be working fine because the raw ADC counts had gone when I disconnected the signal cables. Tracking the signal lines further, I found a whitening chassis whose +15 V LEDs were all off. I power-cycled the chassis and this resulted in change in the level of the bogus signals, but this did not still give me realistic signals. The +15 V indicators are still off. We need to replace this unit.