Packard Bell TM85 no power

[tomodachi]

Hi,

My motherboard has 17V at power button (there must be 3.3V I assume)
and doesn't power on.
there is no short on motherboard, already tried to remove cmos battery and plugged back with no result. I found schematic and checked power button's 3.3V line and ended up at KBC chip (KB926QF D3) I guess this chip is bad but I need another opinion so please feel free to tell if you have an idea.

Update : I may flash KBC rom but need to be sure if KBC chip is broken or not when there is 17 volt in power button
and below the schematic

[Th3_uN1Qu3]

Re: Packard Bell TM85 no power

Hi,

My motherboard has 17V at power button (there must be 3.3V I assume)
and doesn't power on.

Seen this a bunch of times. It's a measurement error, it leads you to believe it's 17v but it's something else (or nothing at all). It charges from somewhere else (likely thru your probes or fingers) as it is a high impedance circuit. KBC should be fine, this is a power supply problem.

This is the same exact board i have in my Acer 5742G, and i can give you some pointers. My 5472G had been dropped when i got it and there were A LOT of things wrong with it... Previous owner replaced the LCD since it got busted, and then he ran into other issues so he sold the laptop. In the end it required a GPU reflow and resoldering of all power supply ICs. Been around 8 months since and it's still working great.

Resolder all power supply components on the right side of the board. Especially RT8206 (power supply) and ISL6251 (charger). Then check if 3VALW and 5VALW are present. If those check out ok, try powering it on again and see what you get.

[Francisco.s]

Re: Packard Bell TM85 no power

It is normal 17V at power button while in S5 state, and probably kbc chip can´t read correct data from ec-bios, due to data corruption.
Check pin 8 voltage from ec-bios, and reprogram it, if voltage is correct.

17 volts, comes from pr308/307 and pq42 (internal diode) connected to VS.

[tomodachi]

Re: Packard Bell TM85 no power

Seen this a bunch of times. It's a measurement error, it leads you to believe it's 17v but it's something else (or nothing at all). It charges from somewhere else (likely thru your probes or fingers) as it is a high impedance circuit. KBC should be fine, this is a power supply problem.

This is the same exact board i have in my Acer 5742G, and i can give you some pointers. My 5472G had been dropped when i got it and there were A LOT of things wrong with it... Previous owner replaced the LCD since it got busted, and then he ran into other issues so he sold the laptop. In the end it required a GPU reflow and resoldering of all power supply ICs. Been around 8 months since and it's still working great.

Resolder all power supply components on the right side of the board. Especially RT8206 (power supply) and ISL6251 (charger). Then check if 3VALW and 5VALW are present. If those check out ok, try powering it on again and see what you get.

This trick didn't work for my motherboard, I guess its time to flash EC-BIOS.
Since I don't have a programmer I will see my friend to use his programmer and I will update here.

It is normal 17V at power button while in S5 state, and probably kbc chip can´t read correct data from ec-bios, due to data corruption.
Check pin 8 voltage from ec-bios, and reprogram it, if voltage is correct.

17 volts, comes from pr308/307 and pq42 (internal diode) connected to VS.

[tomodachi]

Re: Packard Bell TM85 no power

Thanks all !KBC rom reflashed and mobo worked greatly !

[alihomee]

Re: Packard Bell TM85 no power

great work but a bit confusion hear........what u mean by kbc rom..........what i know is keyboard controller?or u mean bios chip or eprom

[tomodachi]

Re: Packard Bell TM85 no power

great work but a bit confusion hear........what u mean by kbc rom..........what i know is keyboard controller?or u mean bios chip or eprom

sorry, I mean eprom chip

[Th3_uN1Qu3]

Re: Packard Bell TM85 no power

Thanks all !KBC rom reflashed and mobo worked greatly !

Good job. Had the same issue on a Lenovo V560 at the beginning of this year and this was the solution. Actually it's that Lenovo that i've traded for the Acer 5742G i still have and posting from it right now.

However i've seen quite a few laptops that have been dropped or abused lately, and this seemed to me more likely than a bad EC ROM.

[dj_ricoh]

Re: Packard Bell TM85 no power

Thanks all !KBC rom reflashed and mobo worked greatly !

Good job!
Don't forget to attach the dump files you flash.

[Francisco.s]

Re: Packard Bell TM85 no power

Thanks all !KBC rom reflashed and mobo worked greatly !

Which dump did you program?

[tomodachi]

Re: Packard Bell TM85 no power

Good job!
Don't forget to attach the dump files you flash.

Which dump did you program?

Sorry, I forget a lot these days Here is the dump file. Works on Packard Bell TM85 TM86 TM87 TM89.
Wish you good luck with that !

[tomodachi]

Re: Packard Bell TM85 no power

Additional information folks !

Remember to update BIOS after reflash, otherwise comes back again with same problem.
Proven by experience