Sony MBX-197 power circuit, help me think it through

[Plates]

Re: Sony MBX-197 power circuit, help me think it through

I am trying to repair this motherboard which has similar issues to those mentioned above. After applying 19V, the fans spins for about a second then nothing. I have checked the 5R6 inductor out of circuit and it seems fine.

The AO D452s test OK.

There was a low resistance to ground on the VHCore rail so I ended up removing all the FETs to ground (PQ34-41) and main capacitors (PCAP1-6) however, the low resistance was still present. After removing the main processor, the low reistance disappeared.

What should the resistance across the processor supply pins be?

[piernov]

Re: Sony MBX-197 power circuit, help me think it through

Low resistance on CPU VCore is perfectly fine, it'll usually be around 2 to 20 ohms. Same applies for GPU VCore, and PCH VCore too (but this last one is usually higher resistance).
A full short on CPU VCore would be lower than 1 ohm.
If you've got CPU Vcore when you turn on the computer then it's perfectly fine. If you don't have CPU VCore, it may be that the power sequence stops earlier and that's what you have to look for.