I have here notebook mainboard. It had a problem and won`t power on but when removed the charger and battery and press the power button for a time and then put back them everything was good. But after few days that is not a decision.

I will try test the bigger capacitors first or to search for a scheme and look for some logic.

thanks

Other discussion about the case here -> https://forum.allaboutcircuits.com/...ue-have-only-marking-now.151908/#post-1303122

 

Rather than just start changing things, you really should do a few tests first - #1 is always the power rails. Even without a circuit, you can generally
figure out what voltage should be where. Start with the DC_in section. Clip -ve probe to a fixed 0V and probe ICs, caps etc
You're looking for 3V3 / 5V0 / 1V8 or standard voltages around those. Ideally, if you can get hold of an oscilloscope, it will be much easier.
Look up IC specs to find their power pin. For "bad" caps, you're looking for bulges (can be tiny), or leakages.
Start with that and people wild guide you further.

 

Try removing all the ram from the slots and see if it shows any signs of power up, then replace one at a time if more than one fitted. In the last year I have had 3 laptops with one faulty ram board causing the same symptoms you describe. In all cases, the owners had been using them on surfaces that didn't allow sufficient air flow.

 

I have an not cheap osciloscope but still dont have a lot of skills to use it and am a little afraid to use it.

I will use it today again with this motherboard. the board is da0zb3mb6e0 rev:e

Will update the thread with results.

 

recklessrog the notebooks comes "in me" with 2 RAMs, i remove them and install only one mine(which i use for tests) into Slot1. Have cleaned the sockets with contact cleaner and then put the left cleaner out with spray.

 

what happens when you switch on with both rams removed?

 

replace battery

 

The replacement of battery cannot be done.

I will put back 2 capacitors on board will try to power without 2 RAMs

edit without Rams is like with one tested - blink maybe 8 times and that`s that

 

https://ibb.co/hmkoAK
https://ibb.co/mbSPje

Uploading has problems in AAC...

Regulator 0 0 0
13.20V pd13
pq2 1.53v gate
1.58 zenner
14.27 capacitor
000 capacitor
000 capacitor
pc1 000
pc22 000
c near CPU 000 000
max 1999 17 pin Vcc 5.10V
pc120 122 000
g965-18 2pin 000
4119n x2 gate 000
4812 g1 g2 000
4422 g1 g2 000
4812 g1 g2 000

edit1
i see short D-S in 6690as without desoldering the ic. The element should by faulty, right?

 

Here are detailed pictures from today

https://ibb.co/bVjdvU
https://ibb.co/kPXbh9
https://ibb.co/j0xWFU

 

That is some serious tiny / complex motherboard. To be honest, it is not an easy diagnosis even for an "expert" tech. Even worse, trying to guide
someone through. As far as replacing parts with weird / strange markings, you'd need to have done a lot of this type of work, to be confident in
figuring out what the part is, and if it is faulty. There's just too many questions, and too many possibilities.
Do you have a local PC nerd repair guy? or a local PC user group. That may be your best bet.

 

I am the man which do all the things. I do with monitors, computer power supply units and others and others.
As i said i have an osciloscope and if someone tells me conrecete where what to look for i will tell everything.
A man should begin "from somewhere" The education is education but practice begins with such things.

Do you think that

i see short D-S in 6690as without desoldering the ic. The element should by faulty, right?

 

That is one of the problems of having multiple threads. What is "6690". Do you have a picture or a datasheet for it?

 

6690as.

https://www.mouser.com/ds/2/149/FDS6690AS-1008290.pdf

 

OK, whether a short (diode test or ohm setting?) means it is likely defective will depend on whether your positive probe was on the source or drain, whether there was any gate charge (static or a momentary touch with the positive probe can turn on a mosfet), the circuit (e.g., is there a gate discharge resistor), and other faults on the board, e.g., a short between the positive rail or drain of the mosfet and ground (assuming the source is grounded).

 

I suggest resoldering the power connector connections, and the power switch connections. It is an example of very poor quality to only have the power connector surface mounted to the mother board.

 

we have a N mosfet.

i am watching

https://i2.wp.com/electronicsbeliever.com/wp-content/uploads/2015/03/Figure-42.png

should the item be desoldered for this measure to be true?

I am using Diode test mode.

drain negative probe source positive and i hear short

Oposite probes - short again.

 

That's a terrible repair strategy for a motherboard.......in so many ways. You're gonna need a lot of patience and persistence. And a lot of time. Is the board worth it? How many hours do you need to work to pay for used board or have it repaired? It might cost you more for repair.......after you have tried to repair. Some motherboard manufactures will replace older boards for a set fee.

 

let say it`s for the learning purposes...Forget about the money...

and...there is no such board in advertise sites in Bulgaria

 

Then why not replace battery?