I'm newby in your group.
First of all excuse me for my English, I'm from Russia and have no practice. Therefore my posts may contain some mistakes so I'm sorry.
I like vintage computers especially from HP. I have two early models -- HP 9825B and HP 85.
Unfortunately my 9825 isn't work correctly -- I repaired the power supply module but the computer didn't resurrect :(
I checked up all voltages and they are OK. If I disconnect KDP interface cable and make power on -- LEDs are light on and the beeper is sound on.
I checked up the clock frequency -- all OK, approx. 6MHz.
Could you help me with searching of solvetion?