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Router is buzzing

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I bought a used router of eBay (sold as broken, just wanted something to play around with) and when plugged in it buzzes. The sound is coming from near the power jack. Ive tried upping the voltage to 9v but this causes the CPU to heat up quickly and I dont think this is good for it. What should be the first components that I should check? I can post hi-res front and back pics if needed
 
Wow, you caught me here... I thought you meant a wood working router!!! Then when you mentioned 9V, I was totally lost! lol...

Do you have a make and model of said router?
 
Its a Bosch 2-1/4 hp Combination Plunge & Fixed-Base Router.










Just kidding. Its a v1.0 Linksys WRT54G with the little MiniPCI wifi card thing.
 
I would replace the bit in it. It is out of balance.. That will make it buzz.. Or maybe a bad bearing...

Buzz from the router. First off, they are like $39(US) retail today.. Second. There is no speaker in a router that I can think of. Maybe put an ear near it and see what area the buzz is in..
 
Whats the fun in buying something new when you can spend zero dollars and (hopefully) fix something broken? I tried the ear thing and for whatever reason it sounds like its coming from the Wall Wart. But it does the same with another 5v supply aswell (I tried the original and another one). This leads me to believe something is wrong with the router's motherboard. Maybe a short of some kind?
 
Sounds like it is dragging too much current from the wall wart, so look around for very hot power items diodes transistors rectifiers, 7805 that sort of thing.
 
It doesn't sound good to me! - applying 9V (instead of 5V) and the CPU getting hot, either it was fried before, or it's fried now (after too much voltage).
 
In my experience, first thing to check with any device that uses a wall-wart ( AC Adapter ) is the wall-wart itself. Especially something that is generally plugged in 24/7. The filter capacitors fail, you get heavy ripple instead of DC, and whatever they power stops working.

If the wall-wart is bad, then also check any filter caps at the DC input of the device. Heavy ripple current from a failed DC supply can trash these caps as well.
 
Sounds like major problems. Check the power supply section and see if you have the right voltage based on that regulator. If not go back in the power supply and fix it. And pray it did not fry other parts.

Quite a load to make the transformer buzz. :)
 
Power supply is fine. I tried it with another one, and it did the same thing. If it was that simple, I wouldnt have to ask here :p How would I go about testing capacitors? I dont think I have any spares lying around.
 
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I think it has something to do with the input voltage filtering on the board. The most I can probe with a multimeter is around 0.3v after the filtering stage, but a full 5v before that. Also, if I remove the two large filter caps, it buzzes very loudly from the motherboard. I think its toast. Anyone need a router mainboard (maybe for the rj-45 jacks or the leds)?
 
I bet there is a switching supply on the board, generating al the various voltages needed. One of the power devices has probably shorted, overloading the external supply. This maybe happening in cycles as the supply comes up, shuts down due to oveload, comes up, shuts...... creating the buzzing you hear.

Most wall-warts, being Class 2 devices, will open circuit the transformer secondary when shorted. Maybe you have a heavy overload, but either too brief in duration or not high enough in current to pop the wall-wart.
 
Well there are two SO-8 chips on the board, right by the filtering caps and the input. Ill look for datasheets on them, but they look propriatery (no mfg logo)
 
ParkingLotLust said:
Whats the fun in buying something new when you can spend zero dollars and (hopefully) fix something broken? I tried the ear thing and for whatever reason it sounds like its coming from the Wall Wart.
Probably, thouse cheap and nasty transformers often buzz.
 
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