[SOLVED]Old 820-2530 Charger Green then Orange No Power

[rany]

Hi,
We have two 820-2530 not powering up - no fan spin at any moment, exhibiting:
Green then orange light on charger, then we try to jump start by shorting pin 5 to ground, and the orange light disappears for a few seconds, only green remains. Then orange comes back.
Anyone can help with any clues?
And is there a shortcut to testing if SMC is bad?
TIA!

 

[rany]

When you asked about U5000 I checked voltages and SMC_RESET_L was 0.15V on Pin 1 of U5000. Measured more than once.
I am assuming data line from U7000 to SMC is SMC_AC_OK? If yes, not shorted, voltage drop is 0.497.
Also green light on charger sometimes comes back.

 

[rany]

Ok I did replace R5000 and got green and oranges lights back. Still no fan spin.
I tried swapping the SMC and still no change. I am not sure the donor was any good and I don't stock such an old model. Been trying to find another replacement. Will update ASAP.
Thanks for everything till now. Helped me understand the SMC reset circuit for next time, instead of PLZBROing it.

 

[dukefawks]

PPBUS now at 12.56V? PP3V3_S5 present? Resistance to GND on 3V42 rail?

 

[rany]

PPBUS = 12.56V @ F7000
PP3V3_S5_REG = 3.319V @ L7220
3V42 = 0.330 red on ground from Pin 5 of U6901

 

[dukefawks]

I asked for resistance not diode.

 

[rany]

Resistance 5.2 KOhm

 

[dukefawks]

That is too low, MCP is dead, the end.

 

[rany]

Thanks. Will organize a decent burial.

 

[rany]

Can you tell me "why" 5.2 K is too low? Can something else be pulling it down that I need to rule out first next time I see this?

 

[dukefawks]

Could be something else, but from experience it is always the MCP. Anything on the 3V42 bus could be causing it, but in most cases I found it to be the MCP. Normal resistance is over 20K.

 

[rany]

Thank you.
Before testing for resistance, I have to make sure SMC is working properly or this is separate?
Could I have from the beginning tested this rail for resistance and not bothered with fixing the SMC?

 

[dukefawks]

You could have indeed.

 

[rany]

Ok thank you, always a pleasure learning from you guys.

 

[rany]

Just as a last update. Those guys had sent me a donor board together with the board that needed fixing.
i ended up fixing the donor board so to was somewhat a success.