I have a 12 volt, 1.25 amp supply for my wireless router. Every two weeks or so, the zener diode inside shorts out. I'm tired of replacing it. Is this because I plug it directly into the outlet with no protection or is it a design flaw. Will buying a proper UPS solve my issue ? Thank you for reading this.

 

Where is the zener diode placed? What value has it? Did youcheck on the net if others experiencend the same problem?

 

the diode is placed at the very end of the circuit. (just before the output) and it's a 1n4004 (if I see it correctly). Of course the easy solution is to buy it online, but for the sake of tinkering, I'd like to know what's going on.

 

the diode is placed at the very end of the circuit. (just before the output) and it's a 1n4004 (if I see it correctly). Of course the easy solution is to buy it online, but for the sake of tinkering, I'd like to know what's going on.

That's not a zener diode. Looks like the rectifier diode of the transformer. Is that correct? What else is connected to the diodes cathode? Capacitors etc. What is the routers power consumption?

 

you are right, it's not a zener. I can barely make out what's going on because the components are filled with that white goo, to keep em' in place i guess. 2 caps are connected to it.

 

 

Ok this IS probably a zener. See also the component name (ZD1). Do you still have the original one?

It then cannot be the 1N4004.

If you want to know why it gets damaged and what it is for you will need to draw that part of the schematic diagram.

Somewhere there should be a resistor in series with it...

 

Once again you are right, there is a resistor but it's surface mount. I'll just buy a new supply because I need some reliability instead of messing around with this one.
This one seems good but the price is a bit high.
http://www.controlanything.com/Relay/Device/PWR12
The second one is this
http://www.12vadapters.com/adapter/power-supply/12v/1-25-amp-125a-2.html
but it's 1.5 amps. Can I still use it ?

 

The second one is this
http://www.12vadapters.com/adapter/power-supply/12v/1-25-amp-125a-2.html
but it's 1.5 amps. Can I still use it ?

It advertises "for any device that requires stable DC power. ", so I guess it is also a switched mode power supply (as yours probably is, it has a ferrite core transformer).

Just compare the polarity of the connector you have and the one you want to buy. The one on the website has the + pole inside. Also it's dimensions.

 

I'm not that worried about the connector. I could just chop off the one attached to this supply. The center is the positive.

 

I'm not that worried about the connector. I could just chop off the one attached to this supply. The center is the positive.

Then go and spend some money.

Or try to repair your power supply and learn something.

 

I'll just do both. After I'm done fixing it, I can always plug it back it or have it as a backup.