It supports up to 10A, I guess the problem is that I'm using C.V mode at 0,8v and only limiting the current up to 2-5 A, but the resistance is at 4,5 ohms. So it generates only a current around 0,19A.
hi. no, leave the mosfets off. only interested now to resolve the short that is on the consumer side (downstream) that is connecting to fuse F7040, pin # 2.
Consider the following process:
1) leave F7040 off. confirm that F7040, pin #2 has a low resistance to ground.
2) see attached for the fanout of the PPBUS_G3H power rail for this logic board.
3) Remove the backlight as the guilty party by reviewing the fuse on PPBUS_S0_LCDBKLT (F9700). Suggest that you remove but solder one leg on the pad so that you do not lose the fuse - just our method. Just be careful the fuse does not short against any other part or trace.
Now check the resistance to ground of PPBUS_G3H - still low ? Continue...
4) Remove all power. Inspect the mosfet linked to the CPU power rail @ Q7630. This is a DUAL mosfet inside a single package.
Meter in resistance mode.
Check the resistance across the mosfet legs of:
2 & 7
1 & 7
1 & 2
and the other internal mosfet
7 & 3,4,5 (pick any pin since they are shared)
7 & 6
6 & 3,4,5
Record each resistance reading and post them here along with the scale used on your meter.
If the resistance is a low value, the mosfet could be defective.
We want to be sure the mosfet is not leaky for the CPU so that we can proceed to adjust the injection voltage and/or current settings.
PPBUS_G3H powers many rails including PPVIN_S0_VCCSAS0.
The mosfets for each regulator must be working properly to regulate the local rail.
Based on the earlier post, Q7100 - pins 2 & 7 have a very low resistance. Can you confirm it is 19R8 (19.8 ohms) ??
This implies that the voltage from PPBUS_G3H (~12 volts) is likely to have travelled onto the PPVIN_S0_VCCSAS0 rail = CPU voltage. This will have harmed the CPU.
Remove Q7100 and check the resistance out of circuit of this dual mosfet. Make a note of the pin # 1 orientation before removal.
After Q7100 is removed, check the resistance to ground again of PPVIN_S0_VCCSAS0 (L7100, pin # 2). Is it still very low ?
Likely the CPU is dead but wait on the above details and others to comment.
What are the resistance check values of Q7630 with Q7630 removed off the logic board ?
The readings are very low again and Q7630 appears to be defective.
Concern again is that with a defective mosfet, the mosfet is just leaking the high side high voltage present on pin # 2 and flushing it to the downstream load = CPU. The CPU cannot handle PPBUS_G3H as the raw voltage.
A possible savior is that the LOW side mosfet is also very low so perhaps the high side and low side mosfets fought it out and the CPU is still safe but we do not yet know.
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