FX505DT IT8987E

[trepachka]

Re: FX505DT IT8987E

After many attempts, I was able to properly solder the battery charging chip. ACDRV pin is showing 26v and it's stable. REGN is showing 6v and it is also stable. I do get 5v, 3.3v and 1.8v power rails. However, when I plug in the charger, the keyboard lights up yellow and it is slowing flashing. The battery charging pin is showing 2.5v, no battery charging light.
So, there is still a problem since the pin is supposed to show at least 10v in order to charge the battery.

If anyone has any pointers as to what to test next, that would be great.

Also, I was told SIO gets programmed automatically by ASUS motherboard unlike other brands where the SIO chip has to be programmed. Is that true?

[mon2]

Re: FX505DT IT8987E

Best to carefully measure the voltage to ground of each pin on the charger IC.

Does the laptop power on with only the adapter?

If not, measure only with the power adapter.

Post the list of measurements and their pin number.

[trepachka]

Re: FX505DT IT8987E

Both the battery and the charger plugged in:

1 (ACN) 20.3v
2 (ACP) 20.3v
3 (CMSRC) 20.16v
4 (ACDRV) 25.6v
5 ACOK) 3.16v
6 (ACDET) 2.7v
7 (IADP) 2.57v
24 (REGN) 6v
25 (BTST) 6v
27 (PHASE) 2.66v


Any other pin's voltages? Currently the voltage on the red wire at battery is showing 2.54v. According to the schematics, it should be at least 10v.

As I mentioned before, 5v, 3,3v and 1.8v power rails are showing.

[mcplslg123]

Re: FX505DT IT8987E

What about SDA/SCL pins on charging IC? Do you have a Scope?

[trepachka]

Re: FX505DT IT8987E

No scope.

[mcplslg123]

Re: FX505DT IT8987E

No scope.

Then atleast measure voltage on SDA/SCL pins of charger IC.

[trepachka]

Re: FX505DT IT8987E

Both SDA and SCL pins are showing 3.3v with or w/o battery attached

[mon2]

Re: FX505DT IT8987E

Review the high and low side charger mosfets that are driven by this charge ic.

Remove all power. Meter in resistance mode.

Measure the resistance across the mosfet pins.

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.

The high and low side mosfets work together to drill down the adapter voltage to the charge voltage for the battery pack.

[trepachka]

Re: FX505DT IT8987E

Both mosfets are showing similar results:

Source (1-2-3) & drain (5-6-7-8) 192Kohm
Source (1-2-3) & gate (4) 0L
Gate (4) & drain (5-6-7-8) 0L

[trepachka]

Re: FX505DT IT8987E

I noticed as the keyboard cycles thru on/off/on/off repeating cycle, available voltage rails follow the same. They appear, then disappear. Is it possible that the BIOS on this machine is bricked and needs to be rebuilt?

[swammyw]

Re: FX505DT IT8987E

I noticed as the keyboard cycles thru on/off/on/off repeating cycle, available voltage rails follow the same. They appear, then disappear. Is it possible that the BIOS on this machine is bricked and needs to be rebuilt?

i have this same issue with same laptop, no picture and restart loop, have you made any progress?

[swammyw]

Re: FX505DT IT8987E

i have this same issue with same laptop, no picture and restart loop, have you made any progress?

ok, i had actually bad bios and i fixed it with ch341a programmer & good bios dump dl from bios request, btw ch341a can flash 1,8v bios chips if 3,3v mod is done & if u disable/ insulate pin 8 from chip

[trepachka]

Re: FX505DT IT8987E

Actually, I was thinking about reflashing the BIOS since laptop's behavior indicated issue with the motherboard software. Can you, please provide clean BIOS file for me to try? The one you mentioned that worked for you? Also, can you tell me BIOS chip location on the motherboard?

[swammyw]

Re: FX505DT IT8987E

bios chip is between ram cpu & gpu, on top of upper ramslot, there is same kind of chip leftside of upper ramslot but i dont know what that is, my message got deleted when i uploaded biosfile to previous post but it was, FX505DU.zip, badcaps.net*forum*showthread.php?p=969483, actually tbh my case was corrupted ec firmware but it will auto flash it with this bios when making first boot

[Vesko356]

Re: FX505DT IT8987E

bios chip is between ram cpu & gpu, on top of upper ramslot, there is same kind of chip leftside of upper ramslot but i dont know what that is, my message got deleted when i uploaded biosfile to previous post but it was, FX505DU.zip, badcaps.net*forum*showthread.php?p=969483, actually tbh my case was corrupted ec firmware but it will auto flash it with this bios when making first boot

Reminder: rules and organization of this section
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RULES UPDATE for BIOS requests/offers *AVOID BANNING, READ BEFORE POSTING*
https://www.badcaps.net/forum/showthread.php?t=103570

BIOS Requests ONLY!
https://www.badcaps.net/forum/forumdisplay.php?f=40

Reminder about the rules and the organization of the "Troubleshooting Laptops, Tablets, and Mobile Devices" section.

This section and its subsections are about the following classes of devices:

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In the "BIOS Requests ONLY!" subsection go:

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[trepachka]

Re: FX505DT IT8987E

Swammyw, take a look at the snapshot. Is that the BIOS chip you were referring to? This is the only chip I found that has a matching size. Others are kind of smaller in size.

[swammyw]

Re: FX505DT IT8987E

yes, that is bios chip, i think it is worth to try flash it, if the fault is in ec or bios fw