820-00281 Missing PP3V0_G3H

tlough75

Member
So I have an 820-00281 that is at 20V. 30mA and has all the G3H rails up to PP3V0_G3H, which is at .01V and appears to have a 1.0 Ohm short to GND. Sadly thee liquid that I found was to the right of U1100. After looking at this rail rail. I see there only a few components and then U1100 and U7800. I still need to look at where this rail comes from but I do not have a good feeling.
 

tlough75

Member
Fixed two corroded resistors above U1100 and now have PP3V0_G3H.

PP3V3_SUS is .219V now and I am getting 3 ohms...
 

tlough75

Member
This is where I am at now:

PPBUS_G3H: 12.6V
PPBUS_HS_CPU: 12.6V
PPBUS_HS_GPU: 12.6V
PPBUS_HS_OTH5V: 12.6V
PPBUS_HS_OTH3V3 : 12.6V
PPBUS_S4_HS_TPAD: 12.6V
PP3V3_G3H: 3.4V
PP3V0_G3H: 3V
PPVCC_S0_CPU: 0V
PPVCCSA_S0_CPU: 0V
PPVCCGT_S0_CPU: 0V
PPVCCIO_S0_CPU: 0V
PP1V2_S3: 0V
PP1V2_S3_CPUDDR: 0V
PP1V2_S0SW: 0V
PP0V6_DDRVTT:
PP1V8_SUS: 0V
PP1V8_S4: 0V
PP1V8_S3_MEM: 0V
PP1V8_S0: 0V
PP5V_S5: 5V
PP5V_S4: 0V
PP5V_S0: 0V
PP3V3_S5: 3.3V
PP3V3_SUS: 1V
PP3V3_S4: 0V
PP3V3_S0: 0V
 

2informaticos

Administrator
Staff member
Possibly accumulated crap under CPU.
Heat to 180-200 degrees, for 15-20s.
May need to do the same with SMC and U7800.
 
Last edited:

tlough75

Member
Yeah, I think so. DO you know of anyone that has reballed one of these boards by hand? I do not have a BGA reball machine. I do have the stencil for this chip though.
 

tlough75

Member
Just to reiterate:

PP3V3_SUS is currently at 1.1V. This signal is created by U8200 via pin 3. U8200 is supplied by PP3V3_S5 on pin 2 which is supplied from U7650, which it has 3.3V. U8200 is told to turn on by the power rail PM_SLP_SUS_L which comes from pin 238 of U1100, which by no coincidence is also the only IC with foreign material under it from liquid damage. This signal is at 1.5V.
 
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