820-00165 2 boards same problem

[No-Clean]

2 boards same customer, one is clean the other one has some corrosion but nothing bad weird thing is that they both have the same simptoms.

Boards start up, fan spins, I get 1.8v on PPVCC_S0_CPU fan spins for about 5-6 seconds, stops then starts again this time stays on and draws about 0.130a steady but there is no USB activity.

I tried clean ME BIOS and same thing.

 

[2informaticos]

Some other history about what happened?
Especially for the clean board.

Do you get all voltages from pages 57/58?
Also check at L/C blocks near CPU.

 

[No-Clean]

Customer states that Mac was taking a long time to load the OS and sometimes it would not load at all, then one day they both started to not turn on at all, both are machines used in a company all day long.

All Caps and Coils above CPU measure 1v when board is running except for C1031 1.8v for PPVCC_S0_CPU

If you mean page 100 or sheet 62 (Power Aliases) of schematic for board 820-00165 then yes, I have checked and all voltages are present.

 

[2informaticos]

I mean pages 57/58; Power FETs and Misc Power Supplies...

Try full known good working BIOS.

 

[No-Clean]

Thanks for the baby steps, all voltages are present from pages 57/58

I have now tried 2 know good bios and even swapped the BIOS chip from another board same model (Dirty ME) just for testing and the board behavior is the exact same.

I have done the same thing on both boards and same result.

 

[2informaticos]

Did you try both USB ports?

Connect speaker to the board and check if beeps RAM error.

You can try heating CPU with quality flux, may be corrosion problem...

 

[No-Clean]

Same problem on both ports, no sound at all during startup.

 

[No-Clean]

Heated CPU with good quality flux and same thing, this Macs are going back to customer.

Thanks for your time and help.