ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

[jkyoho]

I recently fixed a FA506IV cam with Vram mosfet short on Vin(19v）to ground. Got both mosfet replaced and now laptop could turns on and GPU everything works but battery not charging. Battery status shows 100% on both BIOS page and Windows system.
Measured voltage got 0.3v on battery red lead not going up. charging mosfet gate low and 19v not passing through inductor.
I also tried dc bench supply 14v charge directly onto battery but seems not drawing anthing.

Any idea?

[mon2]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

Check the voltage on each and every pin on the battery pack.

The suspects are the SMBUS pins and the local ESD diodes.

Post the schematic / boardview files if available.

[jkyoho]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

schematic is similar to FA506IH. Will post BQ24780S pin voltage later on.

[piernov]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

https://www.badcaps.net/forum/showthread.php?t=90356

Some of the above points at 2.1 No Power can also apply to battery charging so you should check them as well (in particular 2.1.3. Shorted DC-in MOSFET).

[jkyoho]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

I checked HI-side mos and lo-side as well diode reading seems normal, no internal short

[mon2]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

Be specific on the references to make it easier to follow for other readers.

From your post, assuming that you have inspected the battery charging mosfets @ PQ36, PQ55 & PQ38 ? Confirm it.

Also post the actual measurements so others can review the details and/or learn from them.

See attached. @Piernov is referencing to review the DCIN mosfets @ PQ33 & PQ34.

I was requesting the voltage details of the SMBUS lines. Meter in DC volts scale (5 volts or higher is ok) -> red meter probe on SMBUS line under test; black meter probe to ground. Voltage reading ? Repeat for the next interface line.

Update:

What is the voltage reading (with the battery connected) of BAT_PRS# ?

[jkyoho]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge



YES, I have inspected PQ36,PQ35, PQ71& PQ38. diode reading good.
BAT_PRS# is 0v. LOW . So battery present

[mon2]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

1) What is the voltage of ACDET on the charger IC (PU6, pin # 6) ?

2) The ACDRV voltages are too low to turn on the DCIN mosfets @ PQ33 & PQ34.

3) Remove all power / no battery. Meter in resistance mode (start with the lowest scale).

Then check the resistance across the DCIN mosfets as follows:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate(4) & drain (5-6-7-8)

Post each measurement. If the reading is '1' or 'OL' on the meter, switch to a higher scale.

Also post the meter scale for each measurement.

If the resistance is too low, the mosfet is defective and needs to be replaced.

The TI charger IC requires a number of conditions before it will charge the battery so waiting on your ACDET reading.

Updates:

1) attaching the datasheet for the DCIN mosfets = N-channel.

2) On an N-channel mosfet so the gate voltage has to be HIGHER than the source to turn ON the mosfet. Typically TI likes to use ~6 volts HIGHER than the source leg to turn it ON.

3) What is the voltage of your applied battery ? Suspecting that it is not 19v3 on the battery.

With the adapter connected -> the gate voltage being too low to have the mosfet technically ON -> suspecting that at least one of the mosfets is defective (PQ33 and/or PQ34).

Would you have a donor board ? The mosfets are quite common and can be replaced with others.

Still proceed to do the resistance checks on these mosfets as a confirmation.

[jkyoho]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

My bad, ACDET is 2.65v on BQ24780S PIN6
OMG, you are right, for PQ33, I have low resistance around 2ohm on DS,SG and DG. PQ34 has 18 ohm on GS, DS and DG about 78k ohm.

FYI, I have auto rate UT61E DMM

[mon2]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

I will suggest to replace BOTH of these DCIN mosfets - they are quite inexpensive. You are in TO and should have lots of access to such parts - if not shout back and will see if we can hunt them down.

DK / Mouser / Arrow are outside sources for the same.

The ACDET voltage is good.

A bit concerned about the TI charger IC as well since the conditions appear to be OK but with defective DCIN mosfets, the charger IC may be folding back and not allowing for further charging. That is, the ACDRV is low when expecting ~25v on the gate of each DCIN mosfet. Just a guess that the charger IC is turning OFF this flow of events.

Respectively - not a bad idea to hunt for replacement mosfets for the DCIN x 2; battery charging mosfets x 3 and the charging IC itself.

Each are easy to source from Aliexpress but if in a rush - shout back. We may have some here in the building but need to check...

[jkyoho]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

Thank you, hunting on DK for DCIN MOSFET now, charging ic I can grab one from a donor.

[mon2]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

You can also review Mobile Sentrix but believe they only deal with business accounts.

https://www.mobilesentrix.ca/catalog...p&p=1&q=mosfet

BUSINESS LOCATION & HOURS
25 Planchet Road Unit 5, Concord Ontario L4K2C5
Monday - Friday, 11AM - 8PM EST
Saturday : 12 PM - 6 PM (EST)
Customer Support Number :+1 (647) 317-3118

We seem to be ordering from them every other day lately. Send me PM if you wish to source from them and do not have an account.

Otherwise Digikey is great. We have used TI parts to replace such mosfets in the past.

[jkyoho]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

lol. MS I have been dealing with a lot as well mostly for game console parts. But for SMD parts, DK has more variant

[mon2]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

I think something like this should work out fine - you are not drawing this type of peak current (130A):

https://www.digikey.com/en/products/...35NT1G/1793042

The original part datasheet notes 5x6 physical size but the rest should be a drop in replacement. Do proceed to confirm the specs but looks like a winner and is in stock (rare these days).

[jkyoho]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

https://www.digikey.ca/en/products/d...T1-RE3/7566716
I believe this works

[mon2]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

The electrical specs look good but the physical may not be a drop in replacement.

Check the E2 and D2 dimensions on page # 7 of the datasheet.

The original has to be 5x6 but your selection appears to be 4x4. Confirm it.

My bad...D x E dimensions seem to indicate that max size is 5 x 6 so I think you are ok here. Also your pulse current is higher than the one I found earlier.

[jkyoho]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

Yes, I measured the Original mosfet and dimensions close enough to this one.

[jacobtc]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

I had a similar issue with my Asus G14, and a new battery fixed the problem. Also measured very low to none voltage on battery (0-0.4V).. See thread:
https://www.badcaps.net/forum/showthread.php?t=105577

[jkyoho]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

Just post update and thanks to @mon2 advice, after replacing 2x DCIN mosfet, charge ic finally shut out 17.2v to battery and now charging like a charm.

[mon2]

Re: ASUS TUF FA506IV-AS76 vram mosfet short, then battery cant charge

Well done ! Thanks for the update - this will help future readers.