Sony Ericsson CST-60 Charger

Look for a blown fuse or diode.

 

Is this a cell phone A/C desk charger or a car charger?

Diodes should first be checked with a DMM to determine if they are bad or not before trying to replace them.

 

It's an AC wall-wart charger.

Unless it's an easy obvious fix, I wouldn't risk fixing it. If it's repaired improperly, it might be a fire hazard or damage the phone.

You can get a new one at Buy.com or amazon for about $6 shipped to your door.

I don't think you can beat $6 for a brand new one, but RadioShack (AT&T dealer) or an AT&T store might have some used ones laying around, that used to be paired with now un-repairable phones.

 

Possibly ... do you know how to remove it from the circuit and check it?

If it's right near the DC output, it's probably there to keep the cell phone's battery from discharging into the adapter itself (keep the power going in one direction ... INTO the battery).

The trick to cross referencing a zener diode is you have to know the voltage spec. on it and the wattage it needs to handle. As you probably know, there are also plain diodes and even other special kinds.

Also, after you attempt to fix it, I would check the power output with a DMM first (not the phone). I think it should be 5v DC.

And in general (unless you have an electronics supply house local to you) ... although the parts aren't expensive, with shipping and handling, it's hard to get them to your door-step for less than $5.

 

It might be a 3.9v zener diode. Not sure about the wattage (might have to guess-timate from the physical size).

http://www.google.com/search?hl=en&source=hp&q=c3v9+diode&aq=f&aqi=&aql=&oq=&gs_rfai=

Does it check bad removed from the circuit?

 

Yes, you check zeners the same way.

I think 5t is just a manufacture or lot code (you can ignore it).

 

Agreed, but he says it reads "open".

Can he not check for DC voltage just on the other side (input side) of the possibly bad diode? If the diode is open, and everything else is good, wouldn't he get some voltage?

I still say there should have been a pico-fuse in there. Remember, it might look like a diode or even a tiny box-like capacitor.

 

Ya, pretty amazing how sophisticated some of these wall-warts are these days. Back in the old days it was just a transformer .

The photocoupler is likely used in the feedback circuit (shuts the whole thing down when voltages don't look right).

EDIT: Another advantage is this one is eco-friendly. It only starts using a lot of power when there is a load on it.

 

I could send some links if you want but basically it's a small part that will likely have a mA notation on it like a fuse does.

http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=507-1171-ND

Other look like a tiny round capacitor or even a diode.