On Jan 31, 2022, at 1:21 PM, sv1aku via groups.io <sv1aku@...> wrote:
Hi Bill,
see attached PSU schematic I got from a guy back in 2009 when I was trying to repair my HP 54501. I also have the 54501 schematic in PDF ( from 90903 service manual supplement)? if anybody ever? needs it.
Howdy friends, I have a pair of 54503A scopes. Both had the dreaded Dallas semi Battery ram chip go bad.
I purchased a new Dallas unit and pulled the bad installed a socket and the new unit. Now The system will not boot I have garbage on the screen.
Pretty sure I must have broken an interconnect via while removing the old unit. (it did not come out as easy as I had hoped)
I have discovered the schematics for this unit are some kind of top secret as I simply can't find them. I read somewhere there is a former HP tech who works on these. Does anyone have contact information? I would like to send the main board for repair to this person if it can be done for a reasonable fee.
One unit has a bad PSU which is a poor design with the caps up against heatsinks. I replaced the puffed up caps but it looks like the bad caps took out a FET. Thanks to the member who did some reverse engineering? and provided notes I should be able to repair. In the long run I hope to simply get one to the point where I don't have to do the entire cal procedure every time I want to use it.
