820-2530 - Green Light, No Fan Spin

[sws]

Hello,

I'm troubleshooting an 820-2530 that consistently shows green light on charger but does not spin the fan. I'm not quite sure what to test next and I'm hoping for some help.

I have 16.98v on pin 2 of U7000 and PPBUS_G3H appears to be present, though that may be obvious because of the green light. I'm attempting to walk through the troubleshooting logically rather than just trying to probe everything on the board. To that end, I've looked through the forums and watched various videos on the subject too, but any specific next steps would be really helpful.

Steve

 

[2informaticos]

First of all, welcome to the forum!

"PPBUS_G3H appears to be present"
The exact voltage is very important to know!

This is an old machine, MCP could be dead, or close to its end life.
Post resistance to ground at 3V42_G3H rail; measured on ohm scale.

Do you get 3V3_S5 and 1V05_S5?

 

[2informaticos]

You still need time to understand the schematic; be patient, the practice will help.
PPBUS_G3H is correct.

If SMC_PM_G2_EN is present, then 3V3_S5 must be present too.
To avoid any misunderstanding, post U7200 voltages; pins 16, 3, 13, 8, 17.
Use the surrounding components as test points, instead of chip pins.
Also U7750, pins 1, 2, 6, 8.

2.5K at 3V42_G3H is really bad; MCP seems to be dead in this case (more than 30K expected).
BTW, I was expecting that you catch L6995 as test point for 3V42_G3H...

You can stil practice on this board, repairing 3V3_S5 and 1V05_S5 power supplies at least.

 

[2informaticos]

Post PM_PWRBTN_L, PM_RSMRST_L and RSMRST_PWRGD levels.
Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L, at same time.

 

[sws]

PM_PWRBTN_L measured from the test point near C4902 is 0.016V. Is that the only place to measure it?

PM_RSMRST_L measured on R2151 is 0.001V.

RSMRST_PWRGD at R7840 is 0.220V.

Triggered SMC_ONOFF_L across R5016, the power-on pads, and the voltage of PM_PWRBTN_L remained at 0.016V, with no indication of any change.

Steve

 

[2informaticos]

All these signals must be steady high.
PM_PWRBTN_L must drop only pressing SMC_ONOFF_L; which also must be high, rest of the time.

Check PM_BATLOW_L, SMC_ADAPTER_EN, PLT_RST_L and SM_INTRUDER_L.
Post all voltages for U7840.

 

[sws]

PM_BATLOW_L is 3.316V.
SMC_ADAPTER_EN is 3.401V.
SM_INTRUDER_L is 3.401V.

U7840:
Pin 1 RSMRST_PWRGD is 0.151V.
Pin 2 is GND.
Pin 3 P1V05_S5_PGOOD is 3.392V.
Pin 4 CT is 0.429V to 0.430V.
Pin 5 PP3V3_S5 is 3.320V.
Pin 6 is 3.419V.

I'm confused as to where to go next. It seems like I'm missing something.

 

[2informaticos]

Be sure R7840 is good.
If yes, change C7841.

 

[sws]

As would be expected, I don't have that cap, so I'll put together an order and probably get some of the 100K 1/16W resistors. I have 402 package 1/10W, but I'm not sure if they're metal film or ceramic. While I'm putting together the order are there other likely parts that I might need to replace - fully acknowledging that it's impossible to say for sure, but if something around this area is "common" then I'd like to get it on the same order.

Thanks for all of your help.

Steve

 

[2informaticos]

Get some MacBook scrap boards; is the best option for replacement parts...