A1708 820-00840 Wierd!!!

[reassor]

I think i have gone crazy.

No obvious damage on board.

Ammeter shows 20v and around 300-400mA for just a sec then goes down to 20mA

When i check cpu coils with voltometer set to remeber max it shows around 0.95v on all 3 phases.

PPBUS_G3H is constatnt 13V
Charging works when battery connected.

Now wierd thing. When you let the board drain it shows some caps SHORTED on PPBUS_G3H but after 2-3 sec they jump to high values even in diode mode.

Have i gone stupid and it should not act like that?

Also L7030 (TBA_PHASE) jumps to 4v then 7v then 13v and back to 4.9v (stays that way) (i might have saw wrong some voltage cause its fast)

Last thing q7065 with bat disconected is floaty 13.6v - 12.9v on "TO/FROM BATTERY" side (should it even turn on without batt?) if thats not normal then ISL is going crazy.

Im not a PRO so do not laugh please

Thx in advance for some pointers.

[reassor]

Re: A1708 820-00840 Wierd!!!

No one?

[mon2]

Re: A1708 820-00840 Wierd!!!

Check and post the resistance to ground for PPBUS_G3H. If the value is not super then remove the fuse inline this rail.

Check if ppbus_g3h is stable again on pin #1 of the removed fuse (check the pcb pad).

[mon2]

Re: A1708 820-00840 Wierd!!!

If the value is not super then remove the fuse inline this rail.

Meant to say:

If the value is not super low then remove the fuse inline this rail.

[reassor]

Re: A1708 820-00840 Wierd!!!

Thx i get what you mean.

I tried resistance on it few days ago (now we had to order new PS for usb-c cause the old one was taken away by other client hehe - we use what we can).

From memory it acts wierd like when caps are drained and all power disconected you put multimeter in regular ohm meter not diode or continuity it will show short for few secs then skyrocket to low MOhms (ill recheck that for you tomorow cause board will be fully discharged for sure.)

Simmilar effect is in diode mode (red to ground).

Ill recheck that. And post values.

When you plug in power and ammetter hits 20v it jumps to 0.39A for a sec and down to 0.02A and its steady .

Do you suggest that PPBUS_G3H can become unstable after disconecting F7000 ? (charging side)

Or am i writing silly stuff again (its late ;p)

[mon2]

Re: A1708 820-00840 Wierd!!!

By removing the fuse, you will isolate the power supply the source (U7000) and the consumer/sink (rest of the logic board).

We need to check the power supply is ok and stable without a load.

[reassor]

Re: A1708 820-00840 Wierd!!!

well i broke it ;p

Either isl died or tba_boot1 cap got shorted 4ohms there only.
So for now we need to pause

I need to check if i killed that isl first (didnt check desk under microscope after my buddy was reballing mem chip for some rtx. You can imagine the rest.

Now im stuck at no pp3v3_g3h and no enable for it from u7000. will PM you when its sorted .

Cheers.

[reassor]

Re: A1708 820-00840 Wierd!!!

Sorted the ISL problem by replacing it (was shorted - my bad)

Now i have no charger lol (USB physical charger) to keep poking this motherboard.

What i noticed was that floating voltage on battery in is caused by jumping voltage on that mosfets gate which is drived by same ISL so im assuming since this is a "allways connected battery type" it just keeps trying to probe it.

Other than that EVERYTHING turns on for split second (ammeter is showing 11v and around 200-300mA then goes to 20V 20mA - its just that quick of a pulse) and goes back to S5

Mobo is pristine - will play with it when i get a charger.

There will be some obscure cap shorted somwhere

Still have some minor lines to check.

Will let you know