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Fuses on modern laptop PCB

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tom911

New Member
Evenning Gents,

I suspect that the fuse on my ASUS ROG laptop might have blown up.

Netflix, chill and wine wasn't the best idea and some wine have landed on the keyboard.

Laptop worked fine untill I switched it off and couldn't power it on back again.

Power on is made thorough keyboard press which is connected to main cct though ribbon cable.

Below is the image of the rig and I would be very thankful if you could advise me where I could find the fuse on it.

Images:

1. Main DC power input (top right corner, just below the screen supporting bracket)

2. Main battery, connected through small 8 pin connector, red and black wires.

Keyboard ribbon cable, in the middle, the green ribbon connected to white 32 pin connector.

3. Big picture of the board

5Xwd9yz.jpg

Thanks in advance.

<Mod edit: Removed link and added photo instead>
 
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mjmeodmt

New Member
Hi tom911

Signed up just to answer here...

Laptops these days hardly use fuses anymore.... If you are lucky they use a 0 resistor in some cases. (SMD type). You generally only get fuses on the LCD/LED connection and the VGA/HDMI connection ports, sometimes the LAN ports as-well. I only find fuses on high end laptops they seem to actually care about the components. Anyways since you mentioned a spill.

I would suggest taking out the motherboard from the case. be patient and avoid build up static, discharge yourself to some tool hooked to earth and use a anti-static mat or a wood board over all avoid touching circuit components but also don't over think it. With the board out make sure there are no build up / corrosion spots on the top side (under the keyboard side). Also you said it was working fine which could mean that the spill weren't that much and only damaged the keyboard since the power button is on the Keyboard. (I hate these...)

So thing is if you can give me your model/detail number on the mother board, its usually printed in white and usually inside a printed block. See image here as sample:


Once I know the motherboard details, I'll look through my bin of schematics and see what the setup is on this one, but i'm pretty sure its the same way Acer did theirs on keyboard power button circuit/signal. With that you can at-least test and see if the laptop comes on without the keyboard plugged in. Other wise depending on the findings on the top side of the motherboard (the side under the keyboard) you will need to check the switches(mosfets) on the input rail 19v(usually depends on make), check for 3.3V & 5V ALW. There are a bunch of things and I'll help you kindly.

### EDIT ###
So I forgot to add that sometimes there are a "debug / test" power switch on the motherboard for instances like these where you want to figure out if its the keyboard or motherboard.... Should be a simple micro switch.

Also working from the Acers that do the same thing, having a power switch as a key on the keyboard. You can follow these schematic cutouts and see what you get on those pins. Be careful not to short two pins with the probe.... Anyways since this is Acer based schematics there is obviously a chance that they won't be the same but in most cases I found them to be exactly the same. I'm adding both the KB Connector pinout and the EC part that receive the Signal from the on/off button.
KB Pinout:



You can check the EC pin for as-well for any voltages. Usually in most cases its 3.3V-3.4V And usually its pulled low to initiate a "pressed" signal.
EC Pinout: Pin 114




So yeah good luck. :)
 
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KeepItSimpleStupid

Well-Known Member
Most Helpful Member
One of my Toshiba laptops has two. I haven;t taken it apart yet, but I did order them. Look around the battery area and the power input. Look also for a designation that begins with F. e.g. F1, F2
 

mjmeodmt

New Member
One of my Toshiba laptops has two. I haven;t taken it apart yet, but I did order them. Look around the battery area and the power input. Look also for a designation that begins with F. e.g. F1, F2
Yeah the older laptops no matter which type used to have fuses for almost everything. Input Circuit at the DC Socket, I/O at battery connector... But these days they seem to have made the boards to rather just break so people would lean to replace than repair... Only thing they do these days is have a ferrite bead/filter on the input and sometimes (mostly) they have a reverse protection circuit.
 
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