dell 1558 fm9b mainboard

[pwll computer services]

hi
have a studio 1558 (FM9B MAINBOARD )
no power but does charge battery ,anyone have any suggestions or better still a schematic (must be fm9b not fm9)
andrew

[Uranium-235]

Re: dell 1558 fm9b mainboard

power adapter or power jack. Dells like yours use two power rails, one to charge, one to run

[pwll computer services]

Re: dell 1558 fm9b mainboard

dont think it is power socket as the always 5v and 3.3v are working

[bucephalus]

Re: dell 1558 fm9b mainboard

hi
have a studio 1558 (FM9B MAINBOARD )
no power but does charge battery ,anyone have any suggestions or better still a schematic (must be fm9b not fm9)
andrew

My laptop have similar problem but on battery there is no 3.3v and 5v alw could you please share your experience if you have fixed this problem.

[diif]

Re: dell 1558 fm9b mainboard

Check continuity of power button cable.

[bucephalus]

Re: dell 1558 fm9b mainboard

Check continuity of power button cable.

Hi
Thanks for the quick reply
I have tested miniature tact switch and the cable. they are good and shows continuity. When I press the power button led on the button blinks for 1/2 second then nothing happens. The Charger is working properly and charging the battery. On battery connector 12 volts are present and the charging jack led turns on. I request you to kindly read the complete problem as I have posted it here https://www.badcaps.net/forum/showpo...3&postcount=13

[bucephalus]

Re: dell 1558 fm9b mainboard

Check continuity of power button cable.

The power switch have 2.7v instead of 3.3v.

[bucephalus]

Re: dell 1558 fm9b mainboard

Motherboard have +3v_alw and +5v_alw when connected to AC Adapter but +15w_alw is absent i am unable to understand why? I have checked several components but i am unable to locate the faulty one. please help.

[Oj computer]

Re: dell 1558 fm9b mainboard

Pls I also have issue with the same board.
It doesn't power.
I have 19v at the gate of the second MOSFET instead of 3.3
And the LDO is not present at the pin 21 of the charging ic (pu4) and I've changed the ic still no changes.
Kindly help me sir

[mon2]

Re: dell 1558 fm9b mainboard

Measure and post the voltage readings for:

DCIN

LDO

pins on the MAX8731A (PU4). The LDO does not have an enable pin so it should be always ON.

[Oj computer]

Re: dell 1558 fm9b mainboard

Dcin 19v
ldo 0v

[mon2]

Re: dell 1558 fm9b mainboard

Remove all power.

Meter in resistance mode. Check the resistance to ground of the LDO pin.

What is the measurement and meter scale?

[Oj computer]

Re: dell 1558 fm9b mainboard

Thanks for glur great response sir.
Resistance to grand of LDO pin is 641

[mon2]

Re: dell 1558 fm9b mainboard

What is the meter scale?

The measurement is 641 ohms ?

That is a low reading for the LDO rail. Confirm it.

Consider the remove the capacitor on this rail and check if the resistance changes to a higher value.

[Oj computer]

Re: dell 1558 fm9b mainboard

After removing the two capacitors connected to the LDO rails.
The reading changed to 632 ohms