My HP z620 power is out. So to the best of my knowledge, I attempted to locate the problem and repair it.
The power module contains high volatege parts 300V DC, high enough for your heart to arrest. Please wear high volatage protection globe before touching. And discharge DC high voltage with 10w 100 ohm resistor everytime you are done.
unscrew and open the cover of your power module. The power module consists of two parts, one is AC to DC conversion board and the other is DC to DC converter.
The right board is AC to DC, and the left one is DC to DC.
The building blocks are AC 100 to DC 140 taking ripples. Check this board first.
From this board, there two connectors, one is pure DC 140V and the other is sensing wire?
With AC connected, check DC 140V.
Next there is a part signed as "high volage" with white mark. there two FET which are supposed to drive this DC140V
to transformer. With Oscillo, check AC input and AC out are measured source of FET or the transformer.
inside of white line are two FET, with high voltage, you have to use oscillo scope to check AC. If you observe AC, skip this section.
my case was there was no AC before transformer. so I check sensitive area, noted on the board. There were two micro
transistors, one of which was not functional, so I replaced it with 120V NPN.
Discharge DC 140V with resistor 100 ohm 10 W.
And you have to locate flyback switching IC, TOP266VG.
The above black one is TOP266VG. It is very hard to remove. you can see I almost burnt the board.(above)
If there is no AC across FET or the transformer, then the flyback IC is broken. which is located in the area marked as
"sensitive". The IC resposible for switching converter is TOP266VG. micro trasisitors and photocoupler might be burnt.
so check those parts using your tester.
My case was I had DC 140V, the FET was functional. but micro transistor with input voltage 110V and photo coupler
and TOP266 seemed unfunctional.
I replaced it.
I changed micro transistor above inside sensitive area, 110v operating.
taking top266vg left and new one on right
Let me check if this produces AC on FET. AC out came on screen.
Scope probe should be on FET output above.
I had broken photecoupler, so a replaced.
I got DC 12V out.
What I found was, when TOP266VG was replaced, DC input voltage reached 300V, instead of 140V when no AC on FET was produced.
ANYWAY, it is very dangerous. so use high voltage protection globe. discharge everytime
Good luck.
I thought it has been repaired, but 5V power line indicated 12V. which means it is not yet fixed.
The voltage layout on the connector shown above is written on the right note.
number 1, 7, 10 should be 5V, but they indicated 12V. so I have to find DC to DC converter problem.
This should indicate 5V instead of 12V. Yellow lead is supposed to be 5V.
I started to take all the capacitors coupled to DC outputs.
to be continued.
WHOOOOOPS
correction. I found a new document for Z620 PSU pinouts, according to which, the PSU does not have
5V or 3.3V. read the following:
continued
so my repair seems complete. I was too short minded that I took all the capacitors out so I have to put them back.
good luck.
I am now changing capacitors. I could not get small ones so I had to use old ones. I changed capacitors like this
black capacitors are the ones that I changed.
I put everything together to check output. fan was running, green LED was on. #18 pin indicated 11.85V
I have another PSU and checked the outputs on each pin. # 1 7 10 were 12V. #18 was 11.85V.
Finally, I tested the PSU on PC.
Running without any trouble.
I guess it is fixed.
I label parts I replaced.
TOP266VG Capacitors photocoupler chip transistor(NPN 120V)
Good luck