Two new bad wfd channels have arrived- seen on two recent runs. Note: I
am not claiming the wfd electronics is the problem- it could be the
PMT/fanout or cable. But the data is bad.
1) SM-5 CHANNEL-18 INPUT-1 = 5W02-0. The waveforms are filled with
negative going PMT pulses... it looks like a light leak or a
flasher. Based on the data, I have no reason to suspect the WFD
hardware. Debug this as a problem PMT.
2) SM-6 CHANNEL-08 INPUT-3 = 6C05-0. The discriminator bit for this
input is on too much, even with no apparent signal. Other bits are on a
lot also. Sometimes large (8-10V) pulses are seen in the middle of the
waveform. These most likely aren't real but just in case this is
sparking, you should check the signal with a scope. If you debug with
the mini-acq, a good technique is to swap the input signals and see if
the problem moves with the signal cables. Anyway, it looks to me like a
bad daughtercard channel. To fix it, you should swap the motherboard. We
will decide what to do about d/card swapping later.
To swap the motherboard, remember to set the dip switches so they are
identical to the ones on the board you are removing. You should also
make notes in the WFD logbook (with the license plates) (1) on the page
of the board you are taking out and (2) the page of the board you are
putting in.
Thanks- buon anno,
Ed