(347) 552-2258 [email protected]

820-3437 unstable PPVRTC_G3H and SMC_PM_G2_EN

A

aarone

New member
No signs of liquid damage on this board or machine at all. Doesn't appear to have been cleaned previously.
Sometimes I get a short (5 seconds or so) fanspin out of the board and the CPU heats up but it's sporadic and nothing sustained.


Green light so one wire is working
PP5V_S5 - multimeter (fluke) goes crazy get lightning bolt icon indicates 3.4v-34.4v not seen this before
PPVRTC_G3H switching between 3.25 and 3.41v
SMC_PM_G2_EN unstable 0 to 3.41 bouncing about every half a second.
audible faint ticking corresponding with the power fluctuation near the U2800 area (I think) unhooked the fan and it still faintly clicks.

R8000,8011,8050,8020 not shorted to ground
PP3V S5, S4RS3, S3, S0 not shorted to ground
PP5V S5, S3, S0 not shorted to ground

Tried reflowing (or rehotting as Louis was joking the other day) the SMC, no change.
I'm a bit stuck at this point. Any ideas?
 
Last edited:
A

aarone

New member
PPBUS_G3H varies a little between 8.58 and 8.65 on R7006, doing the same fluctuating on both sides of F7140
L7520 shows a the - sign flashing on and off and a small number of volts like .005v fluctuating
L7560 is cycling from 0 to 3.3 or so volts
 
D

dukefawks

Administrator
Inspect corrosion in U6100 U1900 area and pin8 of U1950. If that is all good, this board is gonna suck. Could really be anything.
 
A

aarone

New member
Yeah no corrosion anywhere unfortunately. Looking at the schematic could a faulty ISL6259 cause improper signaling to Q7130 (which looks like it creates PPBUS_G3H) and that cause the fluctuations on PPBUS_G3H? Is there anyway to meter CHGR_LGATE and CHGR_UGATE to know if the ISL6259 is working properly to communicate to Q7130 how long to pulse to make PPBUS_G3H?

Using a different charger (both are OEM) I get about an 11 second fan spin, then off and then on for a split second and then off again permanently.
 
Last edited:
A

aarone

New member
it's random unfortunately. Sometimes it does it right away when the charger is connected and sometimes it doesn't :/

It wasn't doing it and I pressed down on the U7200 area and it started doing it. No idea if that means anything for real or if it's a red herring.

10 sec on, one off, small blip... then about 30 seconds off and repeat.

heatsink is getting hot during this. I'll take a small video of a few cycles of it and post it
 
Last edited:
D

dukefawks

Administrator
Yeah, this is not a board you really want to mess with. I bet this machine was dropped. Probably a ripped trace/pad somewhere.....
 
A

aarone

New member
donor board it is... :(

It did not die in vain. It gave it's U1950 so that another 820-3437 might live again.
First board I've fixed too.
 
Last edited:
You must log in or register to reply here.
Top