Remove & Repair HWR Pressure loop Signal conditioning chassis
Cavity 1 pressure loop controls were commissioned on 8/3 and shown to work correctly. On 8/7, further testing began of the pressure/resonance control loop in frequency mode revealed that the pressure controls were no longer working correctly: When the loop was placed in manual (open loop) mode, the valve controls were set to -32767 and +32767, which should have produced a pressure transducer readback of +3.3V and +0.7V respectively. Instead, the readings showed: +3.3V (OK) and +2.3V (not ok). Further investigation by removing the Burndy cable and probing the connector pins on the chassis showed that the pressure valve control voltage measured -4.28V, when instead it should have measured closer to +2.5V and never be negative. Suspect that the U1 amplifier for that channel is damaged. Recommend replacement of chassis or PCB in chassis.