Acer 7741g No power from DC but works from charged battery. Please help

[lcdcaps1]

Hi

I hope everyone is well and good.
I have a Acer 7741g Laptop that has suddenly stopped getting power from the charger.

It works from a charged batter but does not charge battery from charger or work without battery present.
I have tried , turning it off and keeping power button pressed, keeping it off, tried new charger.

The weird thing is that both chargers are getting 19V output but when plugged into the jack the green LED on the charger goes out. When I take it out from the jack the charger LED glows green.

I have replaced the jack and have tested the jack. The jack is stand alone so I have tested it and get 19V output.

I have connected the Jack to the motherboard and tested for output on the pins on connector DCIN1 and get 16V on the multi meter but the value on the multi meter keeps fluctuating, goes from 14 to 16V and keeps changing.

I have managed to get the schematic from google and have been reading it but I am need for some help please. I have attached the motherboard schematic.

I know I can replace the motherboard but I would prefer to fix this as this laptop was working fine and just suddenly stopped getting power from charger one evening.

Please can someone help me. I will appreciate it very much.

I look forward to the responses

Many Thanks
Kind Regards

[lcdcaps1]

Re: Acer 7741g No power from DC but works from charged battery. Please help

Hi
I wanted to add that one charger LED goes dim green when plugged into the JACK and one charger LED just goes off when plugged into the JACK but bother chargers produce 19 V output.

[megaraider]

Re: Acer 7741g No power from DC but works from charged battery. Please help

Check schematics on page 54.
Most likely the reverse protection voltage diodes, D10 & D11, are shorted.

[lcdcaps1]

Re: Acer 7741g No power from DC but works from charged battery. Please help

Hi
Maybe a silly question but how could I check if these diodes are faulty.
If I replace them will the laptop work as it should. If possible I would like to order all the parts I need in one go. Also if some one could let me know the best way to test the diode without taking it out and with a multi meter please

Thanks again

[lcdcaps1]

Re: Acer 7741g No power from DC but works from charged battery. Please help

I checked d10 and d11 in continuity mode and my multi meter beeped.
Does this mean that they are bad ?

I also checked U32 AND U33.
U33 has the same voltage that is present at DC IN 1 on pin 1 but nothing on pin 8
U32 has no voltage on pin 1 and pin 8

Does this mean I need to replace d10, d11, u32 and u33
Please people advise

Many Thanks

[dj_ricoh]

Re: Acer 7741g No power from DC but works from charged battery. Please help

Do you understand the concept of a fuse?
Because I'm trying to tell you how the diode works.

[lcdcaps1]

Re: Acer 7741g No power from DC but works from charged battery. Please help

Yes I do
I have tested them but i cannot find a exact replacement for d10 and d11
can some one advise me if d10 and d11 are unidirectional or bidirectional

please

[dj_ricoh]

Re: Acer 7741g No power from DC but works from charged battery. Please help

What diagram its good?

[lcdcaps1]

Re: Acer 7741g No power from DC but works from charged battery. Please help

I have attached schematic on the original post
what do you mean its good

[dj_ricoh]

Re: Acer 7741g No power from DC but works from charged battery. Please help

There are 2.
They are the same?
Where I'm now it takes 5 min to download that diagram.

And I'm on the phone

[lcdcaps1]

Re: Acer 7741g No power from DC but works from charged battery. Please help

yes two of the same
will these work as a replacement
TVS SMD TVS Diodes SMBJ24A-E3 / 52 600W 24V unidirectional --BZXKJ
for d10 and d11

[dj_ricoh]

Re: Acer 7741g No power from DC but works from charged battery. Please help

Can't find your d10 d11 but those are not relevant.

Find pl2 and pl3 lift them up and see if get 19v on pads or charger goes off.

If it goes off then pc9 or pc11 shorted to ground.

If not then move to next step.

Find pd5 pq3 and pq25.

Same thing check voltage on pads and see if it shorts out the charger.

In this line you a couple more caps and one diode link to ground PD1.

If pd1 leakes then it stops the charger.

My money its on that diode. Just lift the diode up and it will work without.

Done 3 acer like this. Diode shorted to ground.

[lcdcaps1]

Re: Acer 7741g No power from DC but works from charged battery. Please help

I cant find any of the mentioned numbers on my motherboard
please can you refer to the schematic and let me know which points i need to test please
Also is there anyway to test without taking components out please

[dj_ricoh]

Re: Acer 7741g No power from DC but works from charged battery. Please help

From first diagram.
Page 31

[dj_ricoh]

Re: Acer 7741g No power from DC but works from charged battery. Please help

Finger the components and see if something heats up.

[lcdcaps1]

Re: Acer 7741g No power from DC but works from charged battery. Please help

I have fingered the components and the diodes get very hot
will these TVS SMD TVS Diodes SMBJ24A-E3 / 52 600W 24V unidirectional --BZXKJ
work for replacements
please confirm
thanks

[dj_ricoh]

Re: Acer 7741g No power from DC but works from charged battery. Please help

Pd1 or yours d10 and d11

[Khron]

Re: Acer 7741g No power from DC but works from charged battery. Please help

For the record, the OP has been bugging me via private messages for the past couple of hours.

http://www.digchip.com/datasheets/pa...J24APT-pdf.php

That's the datasheet for the D10 and D11 part numbers from the service manual, so you can quit asking if those damn diodes you've found are good as replacements - THEY ARE.

[lcdcaps1]

Re: Acer 7741g No power from DC but works from charged battery. Please help

For the record, I was not bugging and was just asking
No need to get angry

[Khron]

Re: Acer 7741g No power from DC but works from charged battery. Please help

Three (unanswered) messages within 10 minutes, while you were also getting help from others on this thread, is definitely "bugging"

But good luck with the repair, now that you have all the information you need.