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820-01041 PPBUS_G3H short

K

Kyle93

Active member
Arrived in January for minor liquid damage around u3100. Just recently came back for warranty but this time looks like PPBUS_G3H short.

Diode mode PPBUS_G3H only 0.030

exact ohm resistance to ground at PPBUS_G3H 53.6

all big coils near CPU

L7410=5.6 OHMS
L7420=5.7 OHMS
L7211=2.4 OHMS
L7221=3.2 OHMS
L7231=2.7 OHMS
L7330=13.0 OHMS
LA340=1.6 OHMS
LA640=1.6 OHMS
LA650=1.7 OHMS
LA350=15.6 OHMS
LA300=222 OHMS

Is it safe to inject voltage?
 
K

Kyle93

Active member
L7660 pin 1 starts at 25 ohms and keeps increasing.

No I don't believe so but please be specific which coils need to be checked. Do not have much experience with PPBUS_G3H shorts on newer boards.

Similar post found here and no mention of 3V3/5V coils were mentioned to check

820-01041 not turning on

hello i'm new, I have a board does not turn on, the usb c ammeter 5.1v 0A in all usb c ports, PPBUS_G3H=0 PPDIN_G3H=5.1V PP3V3_G3H_RTC_X=0 I do not know what measures to take more in these new computers t2 chip
boards.rossmanngroup.com boards.rossmanngroup.com
 
2informaticos

2informaticos

Administrator
Staff member
You don't have a very low value to ground at PPBUS_G3H; specific for shorted CPU power chips.
So you must check all other coils, which can have similar value (50 ohm aprox), as you actually have on PPBUS_G3H.
Just look at schematic and check any coil placed on a secondary power supply connected to PPBUS_G3H; like L3500, LB700, L7600/60, L7700/01, L8102, L9080, etc...
 
2informaticos

2informaticos

Administrator
Staff member
There is not the problem.
If you don't find any coil with similar value to ground and short to PPBUS_G3H, that is good sign.
However, injecting voltage may not heat anything easy, as you don't have a real short.
You may need a thermal cam, to find the culprit.
 
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