Question Laptop wont turn on after replacing motherboard and cpu, am I doing something wrong ?

mikejrdn

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Sep 28, 2018
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I have a Dell Latitude E6430 laptop that died when it was running at 100% cpu for an extended duration. I suspect the power circuit failed. I ordered a replacement motherboard from ebay to fix it. That board didnt fix it so I assumed it was defective and got another one. The second board also didnt fix it so I assumed the problem must have actually been the cpu. I replaced the cpu and that didnt fix it either. I swapped the ram around on the new motherboard and cpu and that didnt fix it.
Currently I suspect that both the motherboards I got from ebay happened to be faulty but I dont want to buy another board until Im absolutely sure that Im not just doing something wrong.

When the motherboard is plugged in (all of them) it makes a quiet chirping sound from around where the dc jack plugs in every 2 seconds or so. If I hold the power button the power button led blinks when it chirps. This happens whether or not there is ram or a cpu installed.
 

Lutfij

Titan
Moderator
No offence but a laptop that's about a decade old(to this year) was better off being retired and the amount of resources spent towards the board/CPU and the time would've been best spent on a replacement laptop, even second hand.

Out of curiosity, are you working with the same power brick that was hooked to your laptop when the first motherboard died? If so, have you thought about replacing the power adapter with a donor unit(don't buy a new adapter yet)? Was any of the innards upgraded throughout the lifetime of the laptop prior to the motherboard dying?
 

lga1156_ftw

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Feb 25, 2020
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have you tested dc jack with multimeter?????? if dc jack and charger are fine then you Also you need to boot up the motherboard "barebone" removed from the case, remove all peripherals and wifi cards etc, boot it on a non conductive surface like wooden table, you can just plugin dc jack + cpu no ram even is needed. If you remove cmos battery (round coin battery) it boots when you plugin power cable no need to press power button.

If you get error sound/ flashing lights about missing ram means something is shorting out, might be LCD, keyboard, USB addon PCB or even power button, you need to find it out adding parts one by one and always remove power cable when you remove / add any part. Just plug it in to test.
 

mikejrdn

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Sep 28, 2018
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No offence but a laptop that's about a decade old(to this year) was better off being retired and the amount of resources spent towards the board/CPU and the time would've been best spent on a replacement laptop, even second hand.

Out of curiosity, are you working with the same power brick that was hooked to your laptop when the first motherboard died? If so, have you thought about replacing the power adapter with a donor unit(don't buy a new adapter yet)? Was any of the innards upgraded throughout the lifetime of the laptop prior to the motherboard dying?
If I just got unlcky and it was bad motherboards from ebay then it will only cost $30 to get a working motherboard.
The cheapest I can possibly get an equivalent laptop used is $200. I've got a 3740qm and 16gb ram in this thing.
I tried many power bricks. I only upgraded the ram and drives before it died.


have you tested dc jack with multimeter?????? if dc jack and charger are fine then you Also you need to boot up the motherboard "barebone" removed from the case, remove all peripherals and wifi cards etc, boot it on a non conductive surface like wooden table, you can just plugin dc jack + cpu no ram even is needed. If you remove cmos battery (round coin battery) it boots when you plugin power cable no need to press power button.

If you get error sound/ flashing lights about missing ram means something is shorting out, might be LCD, keyboard, USB addon PCB or even power button, you need to find it out adding parts one by one and always remove power cable when you remove / add any part. Just plug it in to test.
I have used 3 working dc jacks that work to power other dell laptops of near identical model I have access to.
The mb battery has been removed and the power button held for 30 seconds multiple times on all the boards I tried. These tests were outside of the laptop case on a nonconductive surface.
The power circuitry chirps but nothing else happens.
 
Last edited:

lga1156_ftw

Estimable
Feb 25, 2020
1,334
155
3,390
195
If I just got unlcky and it was bad motherboards from ebay then it will only cost $30 to get a working motherboard.
The cheapest I can possibly get an equivalent laptop used is $200. I've got a 3740qm and 16gb ram in this thing.
I tried many power bricks. I only upgraded the ram and drives before it died.




I have used 3 working dc jacks that work to power other dell laptops of near identical model I have access to.
The mb battery has been removed and the power button held for 30 seconds multiple times on all the boards I tried. These tests were outside of the laptop case on a nonconductive surface.
The power circuitry chirps but nothing else happens.
Yeah but did you remove ram, wifi card, cmos battery, power button cable, LCD cable etc before testing ? i seen this happen with something as simple as shorted lcd panel
 

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