Casper MT55INP1.V.01 Laptop immediately shuts down after power button is pressed

[sorrowfulfloyd]

Hey all,

Just got a no name motherboard for a repair belonging to a Turkish laptop manufacturer called Casper.

Well as you might guess no schematics available at all.
Motherboard is: MT55INP1.V.01

So the 19v comes in ok, 3v and 5v standby is ok, power button has 5v. I draws 0.004 amps from the bench psu, when I press the power button it jumps to 0.040, led comes on then in a blink of an eye it just shuts down 0 amps, no fan spin, nothing. I try again nothing seems to come on ONLY after I remove the DC cable and put it back again, then it's the same story. I checked all the mosfets btw and they seem to work fine.

IT8528E i/o has 3.3v in pins 64, 65, 66 but nothing on 67 which is supposedly for system all pwr good.

I suspect it might be the chipset or the cpu. Computer just died on its own as the costumer tells us.

[reformatt]

Re: Casper MT55INP1.V.01 Laptop immediately shuts down after power button is pressed

A lot of pins on an embedded controller are general purpose and what they do is determined by its programming. Need a schematic as a rule to troubleshoot logic issues around them.

With the these kinds of faults and no schematic, you have to rely on what you can see. Look closely for corrosion and/or physical damage to the board under a microscope. Check for shorts etc or heatspots with a thermal camera. Then identify what each power IC does, and see if you can find datasheets. I've had some faults like this where enables come in from the EC, however there is no voltage or power good signals going back. The power sequence at that point stops and the laptop will switch off. So check each enable and voltage output etc.

Don't waste too much time on it. If the laptop manufacturer had intended these boards to be repaired, they would publish schematics. They don't, so this is what I tell the customer. Practically everything that we know or get given is either pirated or reverse engineered. OEM's are no help.

[mcplslg123]

Re: Casper MT55INP1.V.01 Laptop immediately shuts down after power button is pressed

If you can locate the dc-dc transfer mosfet/IC for 3V/5V, check resistance on the output side ie,VS voltage side.