ASUS TUF FX516PM - no power

[Gigabyte_PL]

Hi Everyone,

I have problem with ASUS TUF FX516PM-HN023T. I checked all resistances on coil and all looks fine. I checked motherboard a microscope and I didn't see anything disturbing.
When I soldered the plus and ground to the input plug, I noticed that on the first mosfet there was 19V at the input but behind it there was 0.020V

the second mosfet has 0.020V at the input and 4V at the output.
The main measuring resistor at the input is 4V.

When I soldered the measuring resistor, I saw that power was supplied to the 3 and 5V coil for a moment and then disappeared. The power supply consumption when the coils are powered is 0.100A

Using thermal imaging, I can see that the point that will only light up is the main 3/5V converter.


Does anyone have an idea?

Thank you.

[Mod. Edit] Boardview (pdf) -> https://www.badcaps.net/forum/troubl...r-asus-fx516pc
Reminder: rules and organization of this section
https://www.badcaps.net/forum/showthread.php?t=117483

[mon2]

Review the above sticky post about charger circuits by piernov.

measure the voltage to ground of the gate pin #4 on the first 2 dcin mosfets. Share the topside markings of these dcin mosfets and also the charger ic that should be nearby. The dcin mosfets are driven by the charger ic. If the mosfets are n-channel type then the gate pin voltage must be higher than the voltage on source / drain pins to enable and typically ~ 25v.

[Gigabyte_PL]

Review the above sticky post about charger circuits by piernov.

measure the voltage to ground of the gate pin #4 on the first 2 dcin mosfets. Share the topside markings of these dcin mosfets and also the charger ic that should be nearby. The dcin mosfets are driven by the charger ic. If the mosfets are n-channel type then the gate pin voltage must be higher than the voltage on source / drain pins to enable and typically ~ 25v.

First mosfet it is: PKCH2BB
Second mosfet it is: QM3058M6AC
PWM CONTROLLER it is: SN51285ARUKR
Battery charger it is: ISL9238BHRTZ-T

1 mosfet
Drain on first mosfet: 19V
Source and gate - 0,02V up to 0,65V

2 mosfet
Drain 0,02V up to 0,65V
Source and gate ~4V

pin #4 on first and second mosfet have 0,02V up to 0,65V
pin #4 on first and second mosfet have 7,3M ohm resistance to ground

[mcplslg123]

You need to measure resistance of dc in mosfets between
01.Source-Gate
02.Source-Drain
03.Gate-Drain

Meter in 200K scale or more. Post the readings.

[Gigabyte_PL]

1 mosfet
01.Source-Gate 4,7M ohm
02.Source-Drain 4,94M ohm
03.Gate-Drain 7,41M ohm

2 mosfet
01.Source-Gate 3,16M ohm
02.Source-Drain 2,10M ohm
03.Gate-Drain 6,89M ohm

[mon2]

With these high resistance readings, the mosfets are not shorted. Yet the mosfets are not being enabled. The charger IC is responsible to enable these mosfets. The next suggestion is to carefully (very carefully) measure the voltage to ground of each pin on the charger IC. This part appears to be in the witness protection program by Intersil (Renesas?) so we will have to hunt down the gory details from other schematics.

The points of interest are:

1) Is the charger IC being powered? Vcc voltage to ground.

2) What is the voltage of the ACOK pin? It should be a logic '1' to denote that the adapter is deemed to be ok?

3) The DCIN mosfets onboard are N-channel type. Respectively, the GATE voltage on each of these mosfets should be higher than the source/drain voltages. The gate voltage should be ~25 volts to enable. This boosted voltage should be supplied by the charger IC through the ACDRV pin. The operation of this charger IC is similar to that from Texas Instruments (BQ series).

For now, you can use the boardview file for this Asus to locate each pin # and post the measurements. Often there will be a 3 legged (dual common cathode diode) used to power this IC. One leg is from the power adapter as the input; other pin is from the battery. This dual diode is used to power the IC by the adapter or the battery; either can power the charger IC. It is possible this dual diode is defective. Power a clear top side pic of this area to study from.

[Gigabyte_PL]

ISL9238BHRTZ
P_CH32_ACOK_10 - 0,0046V
P_CHG2_CSOP_5 - 0,23V
SMB3_CLK_R_10 - 0,70V
SMB3_DAT_R_10 - 0,70V
P_CHG2_DCIN_20 - 0,04V
P_CHG2_PROCHOT# - 0,57v
P_CHG2_VBATSENSE - 0,23v
P_CHG2_HG1- 0,017V
CHG2_BOO1 - 0,023V
CHG2_HG2 - 0,30V

N-MOSFET PJX138K
CHG2_ACOK_10 -0v
CHG2_ACOK# - 0,05 -UP TO 0,27V


BQ24800RUYR

P_CHG_ACDRV_20 - 0,020V up to 0,65V (the same value as on drain on first mosfet)
P_CH32_ACOK_10 - 0,0022V up to 0,03V
CHG_SDA_5 -
CHG_SCL_5 - 0,60V-0,70V
CHG_CMPIN_10 -0,27V
CHG_CMPOUT_0,60-0,70V
CHG_BATSRC_20- 0,24v
CHG_BATDRV_20 - 0,27V
CHG_SRN - 0,27V
CHG_SRP - 0,27V
CHG_ILM - 0,15v
CHG_VCC - 19V
CHG_BST - 0,60V
CHG_BST - 0,23V
CHG_HG -0,23V
CHG_LG - 0,80V UP TO 1,30V
CHG_REGN - 0,60V
CHG_ACN - 4V
CHG_ACP - 4V
CHG_CMSRC -0,60 UP TO 0,75V
CHG_ACDRV - 4V
CHG_IADP - 0,27V
CHG_ACDET - 2,56V

DIODE BAV99W SOT-323
P_CHG_ACDET_R_10 - 4,16V
AC_BAT_SYS - 2,58V
P_AC_SHORT_PRO_10 - 4,70V

[mon2]

Is the BQ24800RUYR also onboard your logic board? Where is it on the boardview file? PU**** ?

NM - found it @ PU8900.

[mon2]

Start with CHG_REGN - 0,60V. This should be 6v0. Can you confirm this measurement again?

[Gigabyte_PL]

mon2 yes, my mistake
on REGN is 6V

P_CH32_ACOK_10 should be 3.3V but there is 0,02V up to 0,05V

[mon2]

If P_CH32_ACOK_10 is not a logic high since it is @ 0,02v, this means you should review PR8901. This 100k resistor is mated with this same open-drain pin and also the REGN (CHG_REGN) voltage feed which you have confirmed to be @ 6v0. Is PR8901 defective? Check the voltage to ground on each side of this pull-up resistor. Do check by removing all power -> meter in resistance mode (200k or higher scale) -> measure the resistance ascross this PR8901 part. It should be ~100k ohms.

[Gigabyte_PL]

PR8901 - 0,002 up to 0,05V and I checked reststance -> 154K ohm after removing all power.

when I checked this resistor I had 101K ohm after removing all power.

[Gigabyte_PL]

Maybe IC charger BQ24 is damaged ? Can I check more to confirm it ? or maybe you have more idea to check

[mon2]

CHG_SDA_5 -
CHG_SCL_5 - 0,60V-0,70V

Check the voltage to ground of these pins again. Each should be ~3v3.

[Gigabyte_PL]

I confirm that last measurement was correct and the values are within the limits 0,5 -0,8V

[mon2]

Locate the pull-up resistors on these SMBUS / I2C pins. You can do this through the boardview file -> select the IC pin with the SDA / SCL function. The net will light up and reveal the pull-up resistor(s). Confirm these pull-up resistors are present on the board. Check the voltage on the other side of these pull-up resistors. If the voltage is present, these pins should be ~3v3.

Next, remove all power. Meter in DIODE mode. Red meter probe to GROUND; Black meter probe onto these SMBUS pins. Check SDA first and then SCL. Post each DIODE mode measurement. No power in checking resistance or diode mode scale on your meter. Diode mode will confirm if these pins are being shorted or not.

[jasko_jacker]

I have noticed that usually when an IC like the bq780s or similar does not enable the mosfets of the 19V line even if all the signals are in order, there is no attempt to understand if the communication with the host is correct. This problem is more common than people think. I understand that a logic analyzer is needed but even a low-cost one is enough.

[Gigabyte_PL]

mon2
I'm probably having trouble locating the pull-up resistors. I have boardview but in a .pdf file and I cannot select these pins.
I tried to check the SDA and SCL path and I find, for example, PR9066 and here I have 0.6-0.7V. I don't have a stable 3V voltage. Maybe you can help me locate it?

I am very grateful to you for your help and attempt to save this motherboard.

[mon2]

Did not realize that the posted boardview is a PDF version only. Go and grab a fresh download just posted that is a searchable version of the Asus FX516PM file. Will catch up on the other request after a quick trip to the grocery store. Using this inside of a BV viewer, you can click on the SDA pin and the entire network of parts will light up that are mated with the same.

https://www.badcaps.net/filedata/fetch?id=3202546

The SMBUS pull up resistors are @ R3020 (P_SMB0_DAT) and R3013 (P_SMB0_CLK). Check the voltage to ground on both sides of these parts - very carefully.

[Gigabyte_PL]

I checked these resistors yesterday.
Today I tested again and here are the results:

Diode test:
R3013:
+3V - 0,440V
SMB0_CLK - 0,480V
R3020:
+3V - 0,424V
SMB0_DAT - 0,439V

Voltage test:
R3013:
+3V -0,5V up to 0,8V
SMB0_CLK - 0,5V up to 0,8V
R3020:
+3V - 0,5V up to 0,8V
SMB0_DAT - 0,5V up to 0,8V

Thank you for new boardview.

Additionally, I would like to mention that I make measurements on a motherboard removed from laptop case. Service power supply supplies power through cables that I soldered to power socket.
Battery is disconnected as well as other tapes.

__
EDIT
Is there any proven solution to check whether the BQ24 IC is damaged?