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820-01987-A 5V @ 0.02A, PPBUS_G3H low but not short?

C

CGid

Member
Have a board that came in for not turning on.

Readings on the board are as follows (Diode Mode)

PPBUS_G3H - 0.087 [0.702V when USB-C is plugged in]
PP3V3_G3H_RTC - 0.376
PP3V3_G3H- 0.434
PP3V3_S5 - 0.387
PP2V5_NAND_SSD0 - 0.410
PP1V8_S5 - 0.305

Another post mentioned a failed Q7030 which I have 5V on.

Any where to check next?
 
C

CGid

Member
No other coils are around this. L8100 is 0.100 and that's the closest in measurement. everything else is 0.3-0.5.

L7420 & L7410 - 0.005 (3.4 Ohms)

With F7000 removed.
C7050 - 0.553
 
C

CGid

Member
L7702 - 0.065
L7420 & L7410 - 0.006
L8100 - 0.112
L7210 & L7220 - 0.007
L7270 - 0.029
L8102 - 0.157
L7030 - 0.490
L7690 - 0.442
L7670 - 0.427
L8410 - 0.893
L8450 - 0.427
L6901 & L6900 - 0.427

L9080 - 0.416
 
2informaticos

2informaticos

Administrator
Staff member
OK, then is safe to use voltage injection method.
There is not very low resistance to ground, so may not get anything really hot.
But a good thermal camera can show something a bit hotter than rest of the board.
Anyway start with lower voltage, you may have luck and thermal avalanche occurs.
Don't go above 13V.
 
C

CGid

Member
Got it working!

For forum search sakes.

Injected voltage starting at 1V and slowly raising it until I had current draw.

5V @ 3a gave a 30-40mA draw. Under thermal I was able to see one of the right speaker amp ICs glowing. U6550. After replacing with one from a donor, the board charges and boots without issue.
 
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