Non Mac - Gaming laptop BQ24735 circuit is being stubborn

[down1nit]

Hello, I’m troubleshooting a rather nice gaming laptop with a battery issue i can’t seem to figure out.

It does not charge the battery though it seems like it’s attempting to.

I found both high and low side PHASE fets shorted internally, replaced them with WHAT I THINK is are equivalents (og = SM4839 replace=AON 4800B even though it has lower drain it should still work as a proof of concept right?) as well as replaced the bq24735 chip just in case, my last one.

DCIN > Q8802 > CSR > Q8800 > B+ is the main input chain, and I’m only getting 3.0 something volts on Q8800 drain which is the battery switch. The gate on Q8800 is at high at 19.6 volts and I guess it's a dead battery but, it's supposedly brand new.

CMSRC 19.3
ACDRV 24.19
REGN 6V
ACDET 2.6
SCL/SDA are present, i need to dig into this
ACOK 3.1

ACOK low?

The double diode D8801 seems suspect maybe or the resistor?

 

[down1nit]

boardview and schematics I've been using in case.

edit: files are too large to share. I found them on Electronics Repair School's Discord by searching P5NCN

 

[2informaticos]

Change Q8802, is burnt; its internal diode should allow current flow anyway.
First, be sure to have good diode mode reading at R8800.

 

[down1nit]

Edit discard this I think I may have made a mistake in my initial post. EDIT 2 YEP I REALLY DID. Changing Q8802 and all the rest right now to it's default state (minus the shorted fets) and remeasuring. Continue to ignore, i'll reply when I've fixed my initial post.

 

[down1nit]

OK I have updated the main post, it's probably just a dead battery, but can anyone tell me about D8801 being low on pin 3? Is that right? It measures 3.1 and 19.6 on the anodes but 19.3 on the cathode, there doesn't seem to be any reason for it to be pulled down, but this schematic is labelled oddly.

 

[2informaticos]

D8801 is used to power U8800A; from charger, OR battery.
It is correctly marked on the schematic; pin 3 is the single side pin on the package SOT-23-3.

 

[down1nit]

Well I reassembled it to wait for the new battery but now it doesn't power on from the AC. It gets all the way past PM_RSMRST, ME_AC_PRESENT, and SUSWARN, but when I short PWR_SW no action happens, no extra current drawn seemingly. Super IO is bad?

what have i done to my boy?!

 

[2informaticos]

"I short PM_PWRBTN"
Why doing that?
KBC controls that line, when detects the drop pulse on PWR_SW#; that is the signal from power button.

 

[down1nit]

Typo, it was in my brain.

I know which one to short, but typing all this out gets confusing. Can you or someone please skim post #7 again without my inadvertent distraction?

 

[2informaticos]

So it works on battery alone?
Did you test on charger, w/ and w/o battery connected?

 

[down1nit]

The situation as of now is I press the power button (on it's button board connected to con5602) and I get a red light from PWR_LED but no other activity. PWR_SW goes low and PM_PWRBTN stays high. Current draw stays the same and nothing heats up above normal.

Is this the EC? Should I be looking for signs of life on it if so how can i do that?

The battery is faulty and a new one is incoming.

 

[2informaticos]

If you casn't detect drop pulse on PM_PWRBTN# (at same time when pressing PWR_SW#), then KBC is suspect.
Of course, you must check its basic signals, before blaming it; like lid, reset...