820-3476 Green/Orange light, Not turning on, Corrosion around U7501

SamMac

New member
Hey everyone,

I have a slightly liquid damaged board which initially had no light but there was corrosion around U7501 so I replaced the the chip and also changed capacitors C7500 (one pad was completely destroyed so made a jumper going to Pin 23 of U7501) and C7503. No I have a green which now turns to orange light but still not powering on and nothing warms up either.
PPBUS_G3H12.56V
PPDCIN_G3H16.41V
PP3V42_G3H3.42V
PPVRTC_G3J3.42V
PP5V_S51.7001V
PP5V_S40V
PP5V_S00V
PP3V3_S00V
PP3V3_S30V
PP3V3_S53.29V


I'm basically getting no 5V (besides 1.7 on S5) and no 3V3 RailsThese are some of my readings and I have checked all the rails but nothing else looks damaged and not sure where to go from here.

Many thanks for any help.
Sam
 
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dukefawks

Administrator
Double check if pin 23 is actually making contact with the chip as it usually is destroyed.

SMC_PM_G2_EN present?
 

SamMac

New member
Everything but fan and dc board connected.
Both capacitors giving the same voltages (1.7V) and looks fine.

Won't be able to check Pin 23 since I am doing this at home and microscope is at the workshop. But it seems good as there is continuity.

SMC_PM_G2_EN is present with 3.4V
 

2informaticos

Administrator
Staff member
"Both capacitors giving the same voltages (1.7V) and looks fine"
Already knew that...
I asked to remove them and see if voltage rise.
Don't you imagine better method to check components than the eye???
 

SamMac

New member
Quadruple checked Pin 23 and its only giving 0.6V and changes everytime i make an adjustment to the jumper (goes up to 1.5V)

Removing either capacitors does nothing to the voltages
 
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