Circuit board for laptop cooler pad, fans dont turn on

Thread Starter

AllAboutMyFailure

Joined Apr 28, 2019
6
Greetings,

Ive got a problem with a circuit boatd of a seemingly cheap laptoo cooling pad, the circuit board which was responsible for the power delivery to the fans have stopped working. i am not sure if it is the fault of the ubs socket goung bad, but that doesnt appear to be so since theres two connectors and none of them work.

It appears to br a simple circuit on a pcb with a 100 microfarad capacitor and a a NEC D882p transistor, none of ehich appear damaged or blown.. Theres also something of a potentiometer, or not evrn, a simple scroll wheel which had a notch that would make it go to either an off position, or regulated power of the fans. in 3 stages. i assumed it failed and soldered it out, but being a complete noob that i am o couldnt tell what, and if anytjing is wrong with it. I have very very minimal onowldge of electronics, but i want to het it working. Can i bypass the thingy and make it work again so that the fans are always in the 100% amperage mode?

Thanks
 

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dl324

Joined Mar 30, 2015
10,758
Can i bypass the thingy and make it work again so that the fans are always in the 100% amperage mode?
Since we don't have the device so we can trace how the "thingy" is connected, we can't say.

BTW, you also seem to be a "complete noob" when it comes to spelling and grammar.
 

Thread Starter

AllAboutMyFailure

Joined Apr 28, 2019
6
SO what can i do in that case, what sort of pictures am i supposed to take? they are as close and as detailed as i could have gotten them. Should i tyr to find a schematic for some off brand polish piece of junk which barely works? i doubt htey are online. I am not a native english spoaker, and you should do your research on dyslexia and what it makes typing like. thanks for help. not

I will try to contact the manufacturer of the cooling pad and get back with a schematic
 
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Thread Starter

AllAboutMyFailure

Joined Apr 28, 2019
6
I'm using an i instead of an I since i am humble, and in my language I with a big letter is used only in scripture when God speaks of himself, so i will kindly refrain.

I will try to trace the circuit, i am not sure how to do it, but ill do reasearch it oniline

EDIT:
after a quick google i found out i will need a multimeter to trace the circuit, i dont own one , and i do not want to spend 20 eur for one for a repair of soemthing that cost as much. what else can i do? trying to get the schematic from the manufacturer is my only optino?
 

narkeleptk

Joined Mar 11, 2019
461
You can clearly see the board and circuits in your photo's. Drawing out a schematic is kind of a waste of time imo.
This is pretty simple to check and there is barely any components here. Plug a usb in to power it. use a digital multimeter dmm set to DC and see if your getting 5v at the pins on usb plugs. Then check the outputs of VR1 which I'm guessing controls speed of fans.. The transistor is pretty simple to remove and test with dmm as well.
 

narkeleptk

Joined Mar 11, 2019
461
EDIT:
after a quick google i found out i will need a multimeter to trace the circuit, i dont own one , and i do not want to spend 20 eur for one for a repair of soemthing that cost as much. what else can i do? trying to get the schematic from the manufacturer is my only optino?
You can not fix electronics with out testing equipment. Just throw it in the trash and buy another one.
 

Thread Starter

AllAboutMyFailure

Joined Apr 28, 2019
6
Ill buy a dmm. its not as expensive, and i can treat it as a project, ill fiddle around with and see if theres signal/ what sort of resistances/voltages shou ldi be geting, and what should i probe along iwth the usb connector and where?
 

BR-549

Joined Sep 22, 2013
4,938
Only one cut trace and a jumper will do. But it's risky. Without measuring equipment further damage to USB supply could happen.
 

Thread Starter

AllAboutMyFailure

Joined Apr 28, 2019
6
Hello guys,
im chiming in after quite a long break, but now i've finally the time to do this and i did get a hold of a digital multimeter . Can i get some further assistance on this ?
 

LesJones

Joined Jan 8, 2017
2,641
It looks to me like half of the switch part of the potentiometer has been ripped off. You can see that part of the track has been ripped off the board near where the missing fifth connection to the potentiometer should be. The positive feed from the USB socket feeds the left hand (Looking at the etch side.) connector on the potentiometer. This is one contact of the switch. The next three connections are the actual potentiometer part. The missing right hand connection is the other side of the switch. I think the transistor is an emitter follower with it's base connected to the slider of the potentiometer. You will probably find it difficult to find the correct potentiometer with a switch so fitting a small toggle switch to replace the switch function of the potentiometer is probably the easiest fix.

Les.
 
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