820-00165 No video. Has all voltages but seems to be cycling.

bjf

Member
This board had a displaced pin 21 on J9500 for 3V42. Resoldered that and MagSafe light came back on. Checked all other pins. They're good. Board has CPU and all other voltages that I can find but no video. Has SMC_LID. When I plugged in an external keyboard to try PRAM reset, the light on the keyboard cycles every 2 or 3 seconds. So it seems like it's in some type of loop that I'm not familiar with. I'm attaching pre-cleaning board pics. I've check the SMC area and BIOS area and both are clean and showing good voltages and diode measurements. Can't find any shorts. Not sure what this could be.
 

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dukefawks

Administrator
Resistance on Vcore to GND? I see a bunch of corrosion spots on the bottom too, checked all those resistors? I would not be surprised if corrosion made it under the SMC too.
 

bjf

Member
Vcore resistance to ground is normal at 16Ω. I had previously checked all those resistors alone the bottom and just replaced everything that looked burnt. SMC area looks really clean. I thought this was going to be an SMC issue when I had vcore and no post, but I think the problem is elsewhere. Not sure what else would cause something like this. Something is causing it to cycle.
 

dukefawks

Administrator
16 Ohm is low for these, compare to a working one. I have one here that is over 100 on Vcore. Give SMC some flux and heat to be sure.
 

bjf

Member
I checked a few good 820-00165 boards on my desk just to make sure and they're all in the 15-18Ω range on vcore. The 3437 boards are higher. Ran flux under the SMC and heated it. No change.
 

dukefawks

Administrator
Did you take J9500 off as that is fucked anyway? The corrosion around the CPU Vcore FETs really worries me.....
 
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