Help diagnose router problem

M

Masejoer

Gawd
Joined
Mar 11, 2001
Messages
698
I have a Linksys WRT350N that I've been using for years but yesterday it just turned off. The power LED On the power brick was off so I swapped in a 12v/6A power supply and it would also turn off when connected to the router. I found that when plugging the original power supply back into the router, it would flicker on once a second but go back out. I've opened the router up but the power seems to get as far as I can follow and probe - I lose the traces after some point. I've removed the Wireless N PC card that is installed in these things but the power continues to die out and attempt to flicker back on every second. Before doing everything, I already tried doing a reset but the problem later appeared to be more severe with the powering on and off. The router has been tucked away its entire life without being moved. I can't find an internal short BUT I only get ~1k ohms resistance between positive and negative.

How can I find what may be shorting out the router? Any good way to find a short internally?

Edit:
I'm a retard - I didn't check one of the caps - the filtering cap. I'm getting 0.5 ohms on it so I'll solder a new one in tomorrow.
 
Last edited:
Yeah...pulled out of the circuit, that cap is fine. Something else is shorted. Ideas?
 
I used to do component level work years ago, most cases it's not worth the time these days.

I've seen a lot of dead power bricks, that's an easy fix. But unless there is an easy fix posted online
someplace, I don't generally take the time to troubleshoot to the component level on the box itself.

Buy a new one.
 
impossible to do electrical troubleshooting over the internet unless its a common issue. if i had it in my hands i could tell you, but ......
 
ghost6303 said:
impossible to do electrical troubleshooting over the internet unless its a common issue. if i had it in my hands i could tell you, but ......
Click to expand...

Yeah, there's that.... but also the problem that if you don't have a bench setup with a scope and surface mount equipment, spare custom parts, etc. it becomes a pretty difficult task to fix something that could be cheaply replaced.

Buy a used one on Ebay.
 
This was a used one...for $60. I'm just looking to recover it but it doesn't appear possible to pinpoint without using something like http://www.eds-inc.com/leak.html .

I'm going to just replace these crappy things with some Asus RT-N16's since they are MUCH faster than the Linksys crap (there used to be a TON of refurb 300N's...), are supported with 3rd party firmware as of last fall, have good reviews and reliability from users, and they have detachable antennas without having to modify the unit. Currently I have two 350N's (one dead), and three 300N's lying around - they're always disappointed me about as much as the WRT54G's did in their later years but 15MB/sec through the 350N's was worth putting up with them.
 
bet ya the power adapter is fine. Have you tried measuring the voltage with and with out a load ?
 
Ummm...the power being supplied isn't the problem. A separate, new 12v/6A psu can't be bad too, especially when it and the stock one work perfectly fine on other devices that draw similar or more currents (the 12v/6A is for a T-amp).

The 1k ohm between the negative and positive terminals, and maybe 0.5ohms at the filter cap (may be designed this way though), shows signs of an internal short somewhere. I don't feel like tearing, and possibly ruining, my other 350N down to compare values of each component, although it would be slightly more informative.
 
Your pretty much screwed without a schematic.......like you said, you lose track of the circuit traces. Plus, reading a resistor is easy enough, but how are you going to check other things without knowing the inputs/outputs of the circuit?

Chuck it, replace it.

I will repair physical damage such as caps/ toroids, etc. , but I don't spend time on blown components you can't find without a schematic that you can't get a hold of.
 
Monkey34 said:
Your pretty much screwed without a schematic.......like you said, you lose track of the circuit traces. Plus, reading a resistor is easy enough, but how are you going to check other things without knowing the inputs/outputs of the circuit?

Chuck it, replace it.

I will repair physical damage such as caps/ toroids, etc. , but I don't spend time on blown components you can't find without a schematic that you can't get a hold of.
Click to expand...

I already thought about telling him to chuck it, but thought me might be using this to learn on. Anyhow, its true with out a schematic or a variable psu or a scope, its pretty hard to get this thing fixed. Its worth no time to spend fixing when you can buy a used one or brand new one for cheaper than labour to get it fixed etc etc.

Schematic would help also identifying parts and certain voltage points.
 
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