Hi,
please try to disconnect the HPPR cable from the console (switch off the
console first) and see if the lights come up again after powering up.
Switch off again, plug HPPR back in and switch back on - LEDs now off again?
Then it's possible that something in the HPPR stack is fried and "eats" the
supplied power.
You can then try to eliminate the culprit by first powering up again with only
the cover unit, followed by adding the preamp slices one by one until you
find the one which pulls down the power.
But could of course also be the power supplies…
Good luck,
Bert
> Am 05.08.2025 um 23:38 schrieb Hiscox, William via groups.io:
>
> Dear All,
>0
> 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
>0
>
> <Diagnosed power to HPPR-2 from PSD in AV I console.jpg>
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