[SOLVED]820-3437 Voltage on 5V and 3V3 cycling up and down

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bjf

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Magsafe light is on. No fan. 3v42 is stable. PPBUS_G3H is stable. 3V3 and 5V are all jumping up slightly - S5, S3 and S0. Continual pulsing on L7520. No signs of life on CPU VCORE when plugging it in - no voltage pulse at all. Checked all the SPI ROM data lines. U1950 looks good and is getting stable 3V42 on pin 8. Any thoughts on where to go next?
 

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bjf

Member
No, like all the other voltages, it's going up and down pretty quickly, half a second at most. It's hitting 3.3V and then dropping right down.

As far as the liquid damage, you might want to look at the pics. It's kind of spread around. Louis fixed the image upload so they're good now.
 

dukefawks

Administrator
Well, there is some obvious corrosion around the TPS51980, I would first clean and inspect resistors and traces there.
 

bjf

Member
Hmm... I missed obvious broken traces around R7520 and R7523. Common sense would have been useful for this one. Thanks for sharing some with me. Working fine now.
 
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