Asus G74SX (HannStar 1129) - two motherboards to choose from!

[dohmniq]

Hello,

I bought an Asus G74SX off eBay thinking it was an obvious repair but noooooo....

Motherboard was broken so I ordered one from AliExpress. The motherboard powered up but there was corruption all over the video output, regardless of which output I used (HDMI, VGA, etc. - it was all the same). Looked pretty much like either the GPU or GPU memory needed reflowing or replacing. Sent it off to a laptop repair company, they swapped the GPU and now I get no output at all! (Tried to get some money back from AliExpress seller but no luck there).

Ordered 2nd motherboard from AliExpress (different seller!). This one powered up and gave nice output but then quickly died and doesn't power up. (I have replacement MOSFETs ready to install but am struggling to find out where the issue is).


SO: if you were going to repair one of these motherboards, would you go for the "no video" board or "no power" board? (Don't know if the "no power" board has now fried the GPU, etc. though)

Tried to scour the internet for a schematic with no joy. I'd feel much confident if I could see the circuit diagram but I don't think I stand a chance trying to work it out given the motherboard has tiny vias and such.

The "repair" to the no-power motherboard by the chinese seller was some horribly resoldered MOSFET just by the power socket. (See attached picture!)

On the no-video motherboard this is an FDS 6672 but on the no-power motherboard it's something else.


----

Anyone have a schematic? HannStar 1129 aka N56MB2800 or N56MN2900

[dohmniq]

Re: Asus G74SX (HannStar 1129) - two motherboards to choose from!

Some more details:

"no power" motherboard causes PSU light to flicker so I imagine the motherboard is repeatedly shorting, causing the PSU to reset, etc.

"no graphics" motherboard powers up. If I connect my TV via HDMI then when I boot up the TV recognises that HDMI is connected but doesn't show anything. I'm going to test memory and CPU by booting up a unix USB memory stick and watching network traffic.

[dj_ricoh]

Re: Asus G74SX (HannStar 1129) - two motherboards to choose from!

I will go with the no power.

You need the psu lab and inject voltage until it blows up or heat uo whats shorted.

I guess a fet with ground diacharge or a diode or a cap.

[dohmniq]

Re: Asus G74SX (HannStar 1129) - two motherboards to choose from!

I will go with the no power.

You need the psu lab and inject voltage until it blows up or heat uo whats shorted.

I guess a fet with ground diacharge or a diode or a cap.

Interesting because I had a bet with a friend about how people would choose and we both thought everyone would prefer to repair the "no video" motherboard.

One benefit of having two motherboards is that I can take voltage readings from the "no video" motherboard to check against the "no power" board.

This would all be so much easier with a schematic though. I can't even find where I could buy one, let alone download one for free.

[diif]

Re: Asus G74SX (HannStar 1129) - two motherboards to choose from!

Any reason why you haven't contacted the laptop repair company and asked them to finish the job your paid them for ? It was partly working, I'd want the job doing properly.

[dj_ricoh]

Re: Asus G74SX (HannStar 1129) - two motherboards to choose from!

Any reason why you haven't contacted the laptop repair company and asked them to finish the job your paid them for ? It was partly working, I'd want the job doing properly.

ohh YES!

i will storm the shop with everything i can.

[dohmniq]

Re: Asus G74SX (HannStar 1129) - two motherboards to choose from!

Ah well, the repair place offers "no fix, no fee" so although they tried replacing the GPU their next option (to me) was "replace motherboard" so I just asked for the motherboard back instead. They had a go and all it cost me was courier one way.

TBH I'd rather they had repaired it. I could bought yet another replacement motherboard from AliExpress for less than they wanted for a replacement motherboard.