820-2610 - missing P5V_S3_REG

Atomrepair

Member
Charger light green, but switches off after a while. Power rails stay as below whether light is off or on.

No fans

PPBUS_G3H = 8.4V
PP3V42_G3H_REG = 3.4V
P5V_S3_REG = 0V, no short to ground
P5VS3_EN & PM_SLP_S4_L = 0V, no short to ground
PP1V05_S5_MCP = 1.1V

MCP does not heat up.

Anything left to look at other than blaming the MCP?
 

Atomrepair

Member
smiba - Its actually 8.41 according to my multimeter, which isn't all that accurate, though it performs amazingly well for the pos it is.

dukefawks I'm using a real charger. Don't own a fake. I tried both shorting the pads at R5015 (without keyboard cable inserted) and using the power button with the cable inserted. SMC_ONOFF_L is at 3.4V.
I swapped the magsafe to rule that out - no change.

Further: According to the customer the problem started out of the blue, no moisture damage spotted on the board or inside the laptop, though I havent completely disassembled it. It was fairly dusty at the fans (smoker), but not clogged up and the fans still spin ok by hand.

edit: seems green charger light switching off as mentioned earlier might just have been due to an imperfect connection between charger and magsafe board. I havent seen the light turn off anymore.
 
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Atomrepair

Member
3v3_s5 is at 3.3V
PP1V2R1V05_S5 is at 1.1V

C7771 replaced, no change. (I checked the cap with my ESR meter, its 362uF and 0.0ESR, so was almost certainly fine to start with).
 

Atomrepair

Member
No pulse on 5V_S3 when pushing power or shorting pads (checked with scope)

Rail check:
I wasn't sure what to check and what not, so I went for all the main ones I could find on the overview in the schematic.
PPBUS_G3H no short8,42V
PP3V42_G3H no short3,4V
PP5V_S3 no short0V
PP5V_S0 no short0V
PPVCORE_S0_CPU 5 Ohm0V
PPMCPCORE_S0 4,7 Ohm0V
PP3V3_S5 no short3,33V
PP3V3_S3 64k Ohm0,16V
PP3V3_S0 2k Ohm0V
PP2V5_S0 no short0V
PP1V2_S0 no short0V
PP3V3_S0 no short0V
PP1V8_S0 no short0V
PP1V8R1V5_S3 no short0V
PP1V8R1V5_S0 no short0V
PP1V5_EXP_S0 no short0V
PP1V05_S0 no short0V
PPCPUVTT_S0 no short0V
PP1V05_ENET no short0V
PP3V3_ENET no short0V
PPBUS_FW_FWBOOST no short8,42V
PP10V_FW no short10V
PPVP_FW no short10V
PP3V3_S0GPU no short0V
PP1V1_S0GPU no short0V
PP1V8_GPUIFPX no short0V
PP1V8_S0GPU_ISNS no short0V
PPVCORE_GPU 3 Ohm0V

Is the resistance for the PPVCORE rail normally that low?
 

dukefawks

Administrator
Vcore is normal. This is starting to look like an SMC or MCP problem :( Have you tried booting from a charged battery?
 

Atomrepair

Member
I charged the battery with this board, verified that its working (bat gave ~7V first, ~12 after charging a while). Going to let it charge a little longer, but right now there is no fan spin when trying to power it up with the battery in (tried with magsafe in and out). Not very hopeful.
Can I check wheter its the SMC or MCP somehow? The SMC I could probably replace, though I'm still waiting for my jig to show up from China and have yet to do my first replacement, but it should wind up here eventually.
 

Atomrepair

Member
Toggling? As in, being pulled back to ground when I hit the button and coming back up when I release it? If so, yes it is
 

Atomrepair

Member
PM_SLP_S3_L has 0V, no short to ground. Thats another one that should be generated by the MCP, yes?

I think the crystal is working, I've added screencaps of my scope for both pins



RTC_CLK32K_XTALIN.jpg - RTC_CLK32K_XTALIN
RTC_CLK32K_XTALIN


RTC_CLK32K_XTALOUT.jpg - RTC_CLK32K_XTALOUT
RTC_CLK32K_XTALOUT
 

Atomrepair

Member
Boardview lists multiple XTals, I figured you wanted to see RTC_CLK32K_XTALOUT or IN.
Is it SMC_XTAL_R / SMC_EXTAL at Y5010 you want? Its the one right by the SMC.
If so, reading is below. Schematic says its a 20MHZ crystal, so says the scope as well.
I dont know how to measure the 32KHz its supposed to be putting out, I haven't tested a crystal beyond checking whether there is a wave or not.

SMC_XTAL.jpg - Click image for larger version  Name:	SMC_XTAL.jpg Views:	1 Size:	34.7 KB ID:	25417

SMC_XTAL

SMC_XTAL_R.jpg - Click image for larger version  Name:	SMC_XTAL_R.jpg Views:	1 Size:	35.8 KB ID:	25418

SMC_XTAL_R
 
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Atomrepair

Member
I got my measurements mixed up earlier, measured at the wrong crystal. Sorry about that. Here's the actual RTC XTAL:


RTC_CLK32K_XTALIN.jpg
RTC_CLK32K_XTALIN

RTC_CLK32K_XTALOUT_R.jpg
RTC_CLK32K_XTALOUT_R
 
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