new70 5891p motherboard acer 5742 not charging

[torla]

Only work on battery, not charging not detect AC.
Solution.

this shematic

https://www.badcaps.net/forum/attach...4&d=1392089443

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

Hi,
How exactly die it hell? Having same issue

[keeney123]

Re: new70 5891p motherboard acer 5742 not charging

So this may be a dumb question, but have you check out the power button on page 39 to make sure it is working?

[dycc]

Re: new70 5891p motherboard acer 5742 not charging

give pu18 pins 1,2,3,8 voltages when adapter is connected

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

Hi, sorry guys i didnt see you already answered here.

I was about to check that IC. Problem is that im new to using the multimeter and i need to know how to connect the cables of the multimeter to check the voltages of the pins. I assume one cable needs to touch the pins, but what does the other cable need to touch?

If you can answer here you can ignore my post from the other thread.

Edit: how do i know which numbers you mention correspond to which pins of the IC?

[dycc]

Re: new70 5891p motherboard acer 5742 not charging

Black cable of the multimeter must be connected to ground and red cable to one of the pin i mentioned above

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

Sorry for being so illiterate, but where is ground on the mainboard?
And how do i know which numbers you mentioned correspond to which pins of the IC?

[dycc]

Re: new70 5891p motherboard acer 5742 not charging

Pin

sorry for being so illiterate, but where is ground on the mainboard?
And how do i know which numbers you mentioned correspond to which pins of the ic?

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

HI,

so i found out i can use any place where a screw driver goes in as ground.

Here are the results from the faulty mainboard:
1. 0
2. 3.22
3. 0
4. 0
5. 7.4
6. 3.15
7. 4.8
8. 18.9

I got a healthy mainboard here so i checked there too:
1. 3.2
2. 3.2
3. 3.6
4. 0
5. 7.6
6. 3.16
7. 4.8
8. 18.9

What does this mean? I already tried to clean up a bit where i think there was some kind of liquid since i read on other boards that some people that helped. But it didnt in my case.

What can i do next?

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

@dycc
What can i do next? It would be nice if I could locate the damaged part (maybe this IC, PU18), then i could try to replace it.

Thanks.

[farooquepm]

Re: new70 5891p motherboard acer 5742 not charging

hello mr:samirabi.....ac mode not chariging solution..is 1st you shoud check protection circuit is vin >to PQ 61 MOSFET >THEN CHECK PQ62 HERE VOLTAGE WILL PRESET AFTER CHECK PR351 THIS IS POWER SRC CHECK HERE 19 VOLT AFTER YOU CHECK SRC TO BATTERY PATHE

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

Hello farooq,

i only had time today to check this..

PQ61:
On the side where there is only 1 pin, it has 7,12v. On the other side 2 pins have 0v.

PQ62:
All pins have 19v.

PR351:
On both sides its 19v.

I did not understand what you meant with "after you check src to battery".

Is the info above enough to say if any part is damaged?

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

Sorry for pushing this one up, can anyone can tell me what else i need to do to identify the faulty part(s)? I could desolder parts from the other mainboard and resolder to this one if needed.

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

Hi everyone,

i can desolder and resolder components from my old (working) maindboard to the new one (which doesnt charge).

But since i cant read the schematics i dont know which components to check next to identify the faulty component.

So im trying to get some attention one last time

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

I have reflashed the BIOS (in some other threads this was suggested) but that didnt help.

I needed to change the acer script for that so it wont check for AC.

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

Hi all,

i desoldered the PU18 IC and soldered a new one and i get the same voltages, so it seems its not this particular IC which doesnt work properly.

Can anyone help me identify possible other ICs which could be damaged? I tried to learn it but i cant read schematics yet.

[yousoufos]

Re: new70 5891p motherboard acer 5742 not charging

Hi, have you fixed your problem?

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

Unfortunately not.

I kind of want to repair this mainboard because back then i bought some stuff just for this project... so I am still open for suggestions.

As i wrote earlyer, i've got a working board from which i could desolder something if i could identify this as the faulty component.

[samirabi]

Re: new70 5891p motherboard acer 5742 not charging

So I am giving it a try again and just comparing the voltages between the working mainboard and the faulty one.

I am currently stuck searching for PR298 (or any PRXXX for that matter) on the mainboard.

I figured those must be resistors and there seem to be resistors without labels.

So the question is: how can i even find out which resistor is connected with PU18 if there are plenty of them and they are not labeled?