[SOLVED]820-00165 No PPBUS_G3H

[JohnB8812]

Got this one in with zero liquid damage looks clean as clean can be. Light on charger but no fan spin.

PP3V42: 3.42 volts
SMCBCACOK: 3.3
SMC_RESET_L: 3.3
PPBUS_G3H: 0 volts at the fuse BUT I get 8.58 volts on the coil before the fuse (L7130)

No short to ground on PPBUS_G3H, fuse has continuity, continuity between fuse and coil present.

Checked C7140, C7141, C7143, C7145 for being blown but they check out ok.

Where do I check next?

Thanks.

 

[smiba]

Impossible to get 8.58V at L7130 but simultaneously 0V on PPBUS_G3H.

Are you sure the fuse is not blown or gone into high resistance?

 

[JohnB8812]

That’s what I’m saying!!! Checked for continuity at the fuse on both sides and got a beep. I literally don’t understand lmao it’a the weirdest thing!! Resistance to ground on PPBUS was like .8 so no short that I could find.

 

[smiba]

Resistance in Ohm on the fuse? Should be 0, if it detects any kind of resistance more then just touching your probes together it's dead

0.8Ohm to ground on PPBUS is definitely a short by the way. Inject voltage and find the source of the short.
Keep an eye on the temperature of the CPU because you can't inject more then 1.2V without having a chance of killing it when the CPU high MOSFET is shorting. If the CPU is not getting hot the short is somewhere else and you can increase the voltage further in case you reach the amparage limit

 

[JohnB8812]

Ohhhh ok then yeah I think fuse is dead. Resistance when I measured it today was way more than 0. I’ll check that tomorrow and ohms I think was 240-300 ohms but I’ll remeasure that tomorrow to verify I kinda measured in a hurry. But yeah I’d bet fuse is dead in that case

 

[dukefawks]

The fuse is dead for a reason usually a short on PPBUS.

 

[JohnB8812]

Ok so fuse is dead. Removed short is on pin 2 so system side...is this dead CPU or should I inject voltage?

 

[JohnB8812]

C7620 is split in half. Think I found problem will report back in a bit

 

[JohnB8812]

Replaced the cap and the fuse and PPBUS is back and the machine turns on and boots into the OS! Mark as solved!

 

[JohnB8812]

I do have a question tho as to why the PPBUS_S5_HS caps blow? I've had two this week with the same kind of issue where a big cap blows curious as to why? Bad charger, surge?

 

[Gurmon]

Shitty clone chargers.

 

[JohnB8812]

Ok will alert customer

 

[dukefawks]

Nah, the Chinese chargers will kill the ISL and current sense resistors before killing caps on PPBUS. It is just plain random cap failure.

 

[JohnB8812]

Gotcha that's weird. Well it's working good now so thanks for the help guys! Another one solved and working.