Acer motherboard DA0ZR7MB8D0 showing MAINON signal short

[Nilam]

Dear Sirs

symptoms is when power button pressed power LED turns on then off immediately. when i am repairing acer laptop motherboard all power are ok until i reached MAINON signal which shows short to GND which enables almost all PWM ICes .i checked it on SIO but here it also shorted to GND.

Board details M/B part no :- DA0ZR7MB8D0
SIO NUVOTON NPCE 781LA0DX
laptop acer
Kindly help me .

Thanks
Nilam

[mon2]

Re: Acer motherboard DA0ZR7MB8D0 showing MAINON signal short

Remove all power. Meter in lowest resistance scale.

What is the resistance to ground of MAINON ?

Link or post the schematic of this logic board if on this forum.

[Nilam]

Re: Acer motherboard DA0ZR7MB8D0 showing MAINON signal short

SIO pin 12 is MAINON which has impedence of 0.000 ohm.
Does it mean sio is short ?

[Nilam]

Re: Acer motherboard DA0ZR7MB8D0 showing MAINON signal short

Schematic ..

[mon2]

Re: Acer motherboard DA0ZR7MB8D0 showing MAINON signal short

Let us confirm if the reading is correct.

Can you post a picture of your meter on the scale used for this measurement ?

Is your meter with different resistance scales or is AUTO style ?

When you short the meter leads together, what is the resistance reading ? Is it the same as when you performed this measurement ?

Some meter models will show '1' or 'OL' for over limit status. Then you must switch the meter scale to a higher value to check the proper measurement.

Also, very important - you must remove ALL power when performing resistance checks. After all this, if you really have 0 ohms to ground resistance then yes, that is a pure short.

[Nilam]

Re: Acer motherboard DA0ZR7MB8D0 showing MAINON signal short

Thanks for the reply.