Acer Emachine La-4854P dead

[mcplslg123]

I'm not getting any voltage on PIN 5-8 of PQ11. If i jumper from PIN1 to PIN5 of pq11-system boots fine. So rest things are ok.

So B+ is shorted somewhere but i was unable to find what is wrong.

PR57/62/65 is ok. MOsfet at PQ10/11 and 12 is ok. I have replaced BQ24751a and checked all resistance near Charging ic.

Any ideas friends??

[piernov]

Re: Acer Emachine La-4854P dead

Voltage on pin 2, 3, 4, 5, 7, 8, 10, 13, 21, 28 of PU5 (BQ24751A) when adapter is connected?
Resistance to ground of B+ line?
Resistance across PR57?

[smali]

Re: Acer Emachine La-4854P dead

My suggestion is check PQ10 carefully may be something leakage Drain with Gate...or try to replace this P channel mosfet.

[mcplslg123]

Re: Acer Emachine La-4854P dead

pin2-0.5v
pin3-0.5v
pin4-19.0v
pin5-2.61v
pin7-0.67v
pin8-2.56v
pin10-3.96v
pin13-0.65v
pin21-0.5v
pin28-19.0v
pr57-46.5ohms
resistance to b+ line-infinity in diode mode.

[mcplslg123]

Re: Acer Emachine La-4854P dead

My suggestion is check PQ10 carefully may be something leakage Drain with Gate...or try to replace this P channel mosfet.

Replaced pq10/11/12-still no voltage in pin5-8 of pq11.

[mcplslg123]

Re: Acer Emachine La-4854P dead

measurements of bq24751a is only with ac adapter connected.

[smali]

Re: Acer Emachine La-4854P dead

pin2-0.5v
pin3-0.5v
pin4-19.0v
pin5-2.61v
pin7-0.67v
pin8-2.56v
pin10-3.96v
pin13-0.65v
pin21-0.5v
pin28-19.0v
pr57-46.5ohms
resistance to b+ line-infinity in diode mode.

According your measurement pin#4 voltage must low ACDRV not working..check pc 45 leakage or shortage.

[mcplslg123]

Re: Acer Emachine La-4854P dead

According your measurement pin#4 voltage must low ACDRV not working..check pc 45 leakage or shortage.

Yeh pin 4 voltage is wrong ,should be around 12v instead of 19v but I've already checked PC45 and its ok.

Any further ideads?? This mb is driving me nuts......

[atsio]

Re: Acer Emachine La-4854P dead

Check again your fets.

[mcplslg123]

Re: Acer Emachine La-4854P dead

Check again your fets.

checked again-not faulty. Still changed them-no result.

[piernov]

Re: Acer Emachine La-4854P dead

pin2-0.5v
pin3-0.5v
pin4-19.0v
pin5-2.61v
pin7-0.67v
pin8-2.56v
pin10-3.96v
pin13-0.65v
pin21-0.5v
pin28-19.0v
pr57-46.5ohms
resistance to b+ line-infinity in diode mode.

Resistance across PR57 should be 0.015 ohm, check again. If it's way higher than that it may be bad. Don't forget to take into account the resistance of your multimeter leads and the accuracy of the measurement, the reading may be off by a small amount for such a low resistance.
Voltage on pin 10 should be around 3.3V, if it's not you may have a defective charger IC.

[bachir2004]

Re: Acer Emachine La-4854P dead

I'm not getting any voltage on PIN 5-8 of PQ11. If i jumper from PIN1 to PIN5 of pq11-system boots fine. So rest things are ok.

So B+ is shorted somewhere but i was unable to find what is wrong.

PR57/62/65 is ok. MOsfet at PQ10/11 and 12 is ok. I have replaced BQ24751a and checked all resistance near Charging ic.

Any ideas friends??

let`s keep things simple,first in diode mode measure pq10 , pq11 ,pq12 and reverse black and red probe,

should find something like 490V and OL other side.p channel 4407 is easy to find on scratch boards.and let me know.

[mcplslg123]

Re: Acer Emachine La-4854P dead

let`s keep things simple,first in diode mode measure pq10 , pq11 ,pq12 and reverse black and red probe,

should find something like 490V and OL other side.p channel 4407 is easy to find on scratch boards.and let me know.

Those are very basic things. I have already checked those things before posting for help. Anyway, thanks for your ideas Bachir sir

[mcplslg123]

Re: Acer Emachine La-4854P dead

Resistance across PR57 should be 0.015 ohm, check again. If it's way higher than that it may be bad. Don't forget to take into account the resistance of your multimeter leads and the accuracy of the measurement, the reading may be off by a small amount for such a low resistance.
Voltage on pin 10 should be around 3.3V, if it's not you may have a defective charger IC.

I have replaced charger ic twice-the last one from a workig board just to be sure. So charging ic is not bad-100% sure. It should be 3.3v on pin10 but i'm getting a bit higher 3.9v.

PR57 is ok-i have measured by taking resistance out of the circuit and even replaced it. No result yet.

I have removed lan/cardreader/sound ic.

[smali]

Re: Acer Emachine La-4854P dead

Check the function of PU1( LM358 )

[mcplslg123]

Re: Acer Emachine La-4854P dead

Check the function of PU1( LM358 )

I have checked LM393 as well as LM358A-no problem found, even replaced them. No luck yet.

Client has agreed to take back laptop without charging enabled as his battery is almost dead and he dont wants to buy a new one. So I'm about to deliver it to the client today.

Would have been happier if could have solved the case as its always a learning lesson.

Still thanks for all your time.

[techetronic]

Re: Acer Emachine La-4854P dead

I have checked LM393 as well as LM358A-no problem found, even replaced them. No luck yet.

Client has agreed to take back laptop without charging enabled as his battery is almost dead and he dont wants to buy a new one. So I'm about to deliver it to the client today.

Would have been happier if could have solved the case as its always a learning lesson.

Still thanks for all your time.

hello
did you get the solution

[mcplslg123]

Re: Acer Emachine La-4854P dead

No , I delivered it to customer with charging disabled as customer agreed as mentioned in post#16