1) Today I used a 1.5 V battery, which is comparable to the signal expected from the cavity monitors, to tune the op-amps to achieve a -50 mV signal from each of the cavity monitor signals. The table below shows the voltage output from the op-amp modules, which then goes into the ADC in ROC2 Slot 23 channels 32-37:
Cavity Signal Output Voltage (mV) ------------------------------------------- Upstream Intensiy -51.6 Upstream X pos -49.6 UPstream Y pos -49.5 Downstream Intensity -49.9 Downstream X pos -49.7 Downstream Y pos -49.4
2) Last night and this morning I tested the response of the op-amps and ADC channels. The expected response was observed. With less attenuation, i.e. a larger negative signal, the signal in the ADC appears at larger ADC channel, and with more attenuation, the signal appears at lower ADC channel.
3) While I was testing the downstream op-amp module this morning, I saw that the upstream ADC channels were saturating at low channel. I checked the signal with a DVM and found that the op-amps for the upstream cavity were producing a +10.4 V output from all four channels. I reset the crate and unplugged the inputs to this module, but the +10.4 V output remained. The other four modules in the same crate are working fine. Hence, I believe this module is broken.
I was unable to find a spare op-amp module, so I used three unused channels in the four remaining boards: 1) one from the downstream cavity monitor module 2) two from the raster module
Afterwards, I fine-tuned and checked the signals for all six cavity
monitor channels. The settings still need to be tested with beam to
ensure that everything is working fine.
A copy of this log entry has been emailed to: rom@jlab.org,bdhahn@jlab.org