Date: Tue, 05 Aug 2025 14:38:17 -0700
Dear All,
Regarding our problems with lock and wobb on our 500MHz AV I system. Several
people suggested checking the console fans to make sure they are all working.
We believe that they are, and will verify. Temperatures inside the cabinet
are normal, near room temperature, and there is plenty of airflow.
It was also suggested that I check or replace the HPPR/2 power supply. HPPR/2
receives power through the MDR36 communication cable, which is routed from
the back plane PSD board of the AV I console on the AQS rack.
Observed voltages are at the HPPR end of the MDR36 cable.
It appears from the labeling on the units that PSM1 supplies HPPR+9v; And PSM3
supplies HPPR+/-19V. Is this an accurate interpretation of their function? Are
both power supplies PSM1 and PSM3 faulty?
The Actual measured voltages at the MDR36 cable terminus are as follows:
Pins Required Voltage Actual
1,2 +19V +19.55 19,20 -19V =
~400mV
3-8 +9V ~300mV GND 13, 14, 21-26, 31, 33
On this particular HPPR/2, there is also the Auxiliary power supply cable (Qickmate 6).
Observed for Qikmate 6 pin (HPPR/2 aux power supply):
No -19V on pin 3.
No +9V on pin 2.
Pin 6, +19V is OK (measured as 19.55V).
We removed all three boards, PSD, PMS1 and PMS3. The amplifier sections PSM1
and PMS3 appear in excellent condition, and all fuses were intact, except
for a 5A fuse that was replaced. Upon installation of a new fuse, this
restored power to the HPPR/2 front LED screen and LED lights. There were no
other differences in the voltages or behaviors of the instrument, Lock
routine or Wobb. Based on the lack of -19V and +9V supplies, we still
suspect both power supplies PSM1 and PSM3.
I am attaching a photo of the backplane of the AQS rack where the HPPR/2 power
supplies are located, and the LED status lights while powered up. Again, both
Lock and Wobb functions have failed. The lock failed first, then later Wobb.
Thanks and best regards,
Bill
--
*William Hiscox, Ph.D.*
Assistant Professor
Elson S. Floyd College of Medicine
Washington State University, Spokane
medicine.wsu.edu
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(image/jpeg attachment: Diagnosed_power_to_HPPR-2_from_PSD_in_AV_I_console.jpg)