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

S

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.
[TABLE="border: 0, cellpadding: 0, cellspacing: 0"]
[TR]
[TD="width: 220"]PPBUS_G3H[/TD]
[TD="width: 147"]12.56V[/TD]
[/TR]
[TR]
[TD]PPDCIN_G3H[/TD]
[TD]16.41V[/TD]
[/TR]
[TR]
[TD]PP3V42_G3H[/TD]
[TD]3.42V[/TD]
[/TR]
[TR]
[TD]PPVRTC_G3J[/TD]
[TD]3.42V[/TD]
[/TR]
[TR]
[TD]PP5V_S5[/TD]
[TD]1.7001V[/TD]
[/TR]
[TR]
[TD]PP5V_S4[/TD]
[TD]0V[/TD]
[/TR]
[TR]
[TD]PP5V_S0[/TD]
[TD]0V[/TD]
[/TR]
[TR]
[TD]PP3V3_S0[/TD]
[TD]0V[/TD]
[/TR]
[TR]
[TD]PP3V3_S3[/TD]
[TD]0V[/TD]
[/TR]
[TR]
[TD]PP3V3_S5[/TD]
[TD]3.29V[/TD]
[/TR]
[/TABLE]


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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D

dukefawks

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

SMC_PM_G2_EN present?
 
S

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

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???
 
S

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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