Got an 820-3115 that came in with no power but green light on the charger. Front side of the board looks clean but back side has plenty of pubes, food, and nasty human junk, but I don't see any liquid damage. PP3V42 present, PPBUS_G3H present, but PPVRTC_G3H and PP3V3_S5 are going crazy. On pins 1 and 2 of U2600 I measure them and PPVRTC fluctuates between 3.3 volts and 3.47 volts and PP3V3_S5 jumps from 0 volts to 3.3 volts. Does this mean that U2600 has issues or could it be something else?
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820-3115 not turning on, PPVRTC_G3H and PP3V3_S5 jumping around
- Thread starter JohnB8812
- Start date
Ok so now SMC_PM_G2_EN is present BUT it is power cycling. This has happened to me with PPVRTC_G3H too where I will plug in a known good charger and it will stay constant then after unplugging it once and plugging it back in it will jump between 0 and 3.3.... Pin 1 of 7941 jumps from 0 to 3.3v. Pin 2 of R7941 for P3V3S5_EN_L is 3.4 but also jumping from 0 to 3.4 continuously....
Starting to think there's a blown trace or internal short. Idk what the deal might be also noticed on the back of the board for Firewire and the other ports there were components loose and corroded. I wonder if someone messed with this board before or if it was assembled by someone who was careless.
Ok now I have created a bigger problem :/ I tried a new TPS51125 just to be safe, and when I did, somehow the PPBUS_S5_HS pin quite literally burned the trace. I ran a jumper from C7272 to the pad and then properly soldered the U7200 back on and checked each pad. However, now I still have a green light, but PPBUS_G3H is only .23 volts. It is not shorted to ground, but now I have another problem because I made a stupid mistake. Where would I go from here?
Haha I love me some KC barbecue but not on logic boards! I checked the 51125 area and re did the jumper and replaced the chip. I can say I definitely got a lot better at running that wire and soldering that chip lol, but the short is still 0.27 volts. I did notice around the fuse got hot, so I replaced the PPBUS fuse, but still no dice. If I inject voltage how much should I inject? I don't want to kill the board if it isn't already dead.