HP/DEC/Compaq

Hi,

I picked up a non-working HP 735/99 a few months ago. I finally had a bit of time to replace all the electrolytics in the power supply as some of them vented and damaged the PCB. Following the repair the power supply red LED "pilot" illuminates with the mains power plugged in but the machine still does not power up. I contacted ASTEC and HP with request for some technical information or a schematic but was not successful in obtaining any information. HP does not have it and ASTEC will not release it because the power supply is OEM to HP.

I am curious if anyone has any technical information on this power supply. The HP 735 service handbook does not even provide the pinouts, let alone any more detailed information. The power supply HP P/N is 0950-2081 and the ASTEC model is BM200-3601. Any help would be much appreciated before I dive in ant try to troubleshoot it blind...

Thanks!

I can't give you any answers unfortunately.
It is a common problem with the power supplies in 720, 730 and 735 machines. If you find any solution, I guess many people would be grateful to hear about it. The PSU is the weakest part of those machines. The rest never fails. It's always the PSU.

Thanks for the encouragement! I tried to contact ASTEC again with a request for a schematic or service manual. I also started looking at the pinout and the circuit, but it will be a very slow process.

I would suggest that you replace all the caps on the 5V rail. There are about six and when they deteriorate the PS simply shuts down.

Thanks for the suggestion. All of the electrolytics have been already replaced as some of them leaked and started corroding the board...