PS5 EDM-033 - 2 sec BLOD - CPU and RAM not coming up

[groomit]

Hi,
Bought a defect console eager to repair.
Seller was not very communicative.
Upon arrival I noticed UART Pads had been soldered previously.
Read it out and got:
80810001 General power failure (periphery, GDDR6, APU, data line shorted)
F*CK. Had That before with a chipped APU. But this APU die looked good. However I found flux around it - previously reflowed?

Boot sequence is quite right 325 mA dropping to 9 mA.

Using the thermal camera I can see the SSD controller and South bridge getting warm.
But APU and RAM stay cool (=not initializing?).
Could find no shorts on the SSD controller.
But nearly all Caps from all RAM ICs read dead short.
APU rail also measures quite short.

Except for a totally shorted APU, what could I look out for?

[groomit]

Hmm, found something. The rail from attached picture is dead short (marked red). Is this the RAM rail?
The mosfet measures fine.
When injecting voltage only the direct contact point on the rail is heating up.
Internal short on PCB?

[BwE]

You have a short near F7002, that code you got is wrong/misleading.

[groomit]

You have a short near F7002, that code you got is wrong/misleading.

Hi BwE,
Nice to read you here. I appreciate your work related to console debugging. Please excuse that, as a hobbyist and Linux user, I didn't use your tool with the proper code database.

However, I did quite extensive short checking on various caps - maybe I missed one.
Dou you think this could relate to the mentioned VRAM rail being shorted(=dead short)? I don't see a direct path.

[BwE]

Im not on my PC now so I can't manually look up the code again. It's a 1.8v short? I'll edit this post later if I remember sorry!

[groomit]

Think I'm getting somewhere. One of the tantalum caps measures dead short. Never had them fail before. Maybe because of the low value short and the black colored housing it didn't stick out on thermal camera?
BTW. what are healty APU power rail resistances? If I'm not mistaken there are two phases. Shoud both measure the same?

[groomit]

Okay - success!
The APU power rail was shorted over one mosfet. Was quite a hassle to isolate the faulty one :-D.

Finally I got picture :-)

Just noticed a typo in the title. It was a EDM-031 board. But only difference should be digital vs disk version.

[ongobongo]

How have you handled the fault finding? I have aN EDM-020 with the exact same problem, power rails read nearly short and SSD:/Southbridge start up when powering on but APU/memory is not booting. Did you desolder the DRMOS one by one or is there are better way to do this?

[MadMaxGR]

Okay - success!
The APU power rail was shorted over one mosfet. Was quite a hassle to isolate the faulty one :-D.

Finally I got picture :-)

Just noticed a typo in the title. It was a EDM-031 board. But only difference should be digital vs disk version.

Can you specify which MOSFET was at fault? Maybe pin point on the board? That will help the community.