Help repairing a P375SM motherboard that won't turn on (100% dead)

Thread Starter

rambomhtri

Joined Nov 9, 2015
481
Hi everyone!

I have this expensive custom CLEVO laptop (+$2000) from 2016 and a month ago, all of a sudden, I woke up after using it last night and try to turn on the laptop, and it's completely dead, no LED, nothing, no sign of life, with and without battery, with and without charger.

The laptop was working fine except one USB in the back that stopped working months ago, after using it to power a USB desktop mini-lamp (I don't know which's to blame, but I don't dare to say it's the lamp). The fact is the USB hub where I connected the lamp after a while stopped working. The rest of the laptop was working fine.

Here are some pictures:

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What I have already done (1 month ago when it happened):

1. Connect the motherboard just with the CPU, LED indicators cable and ON button cable, to check if I can at least turn it on before it beeps because there's no RAM. Plug in the charger, checked there was 19.5V between the inside charger pins. Then checked again in the motherboard the pins and there was 19.5V. So, at least was able to guarantee everything was working fine as far as the charger pins in the mobo.

2. I checked visually and found nothing weird. I checked a few transistors near the charging port and the DMM beep was fine in all of them (beeped for a fraction of a second). I don't remember which ones though.

3. I also checked the BIOS battery (it's fine) and also the SMD button to turn it on, it works fine all the way to the flex cable.

Today I started to work in this project again but I noticed something different:

1. The charger is working fine, the plug measures 19.5V between the pins, but if I connect it to the mobo, now the pins in the mobo are showing 120mV or less, while a month ago they were working just fine.

Also I ask here a parallel question: how is it possible that the charger, which is a power source, is delivering 19.5V between pins, but if I connect it to the mobo, those pins go from 19.5V to almost 0V?
Isn't the power source supposed to maintain its voltage no matter what?
Or may be the charger has a hidden protection in case there's excessive current and turn the pins from 19.5V to 0V?
 
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