SMPS help

[Jackdaniel]

heya all

i wonder how can i fix the smps of my CD player, it just failed when i watch a movie and when i opened it up i could not find any problems on the circuit board, there is a bunch of diodes,zener diodes,transistors,a little transformer,inductor,an optocoupler and a power transistor named "MJE13005A" On the circuit board, also i measured the output of it using some LEDs with proper resistors (i dont have a multimeter) the output volts are printed on the board (5V,Gnd,12V+,12V-) but i dont get any volts out and i dont know how to test the Mje13005a transistor and transformer! All i got is a continuity tester to test components, any help?

 

[carbonzit]

Unfortunately, you're not going to be able to diagnose your power supply problems without any proper tools. (Well, maybe if you were some kind of electronics genius, which you clearly aren't, no disrespect intended.)

 

[Reloadron]

To add to what CZ mentions. You don't know for a fact that the PSU is at fault. That is unless you were able to isolate the PSU. What if something beyond the PSU has failed placing excessive loading on the PSU? Without the proper test equipment to troubleshoot the entire picture there is no easy was to determine the problem or more specific the root cause of the symptoms you see.

Ron

 

[Jackdaniel]

is there anyway to test the SMPS transformer? I am almost sure that the transformer is fried! Any help?

 

[Jackdaniel]

any idea guys?

 

[carbonzit]

is there anyway to test the SMPS transformer? I am almost sure that the transformer is fried!

What makes you think that? Scorch marks?

 

[Jackdaniel]

What makes you think that? Scorch marks?

when i tested the primary side of the transformer using a continuity testor there is continuity, but there is no continuity in secondary side of it! Any idea?

 

[Jackdaniel]

any help?

 

[Nigel Goodwin]

I would be VERY unusual for the transformer to have failed, and if it had lot's of other parts usually die as well.

You really need a circuit and at least a multimeter - but unless you're experienced at repairing SMPSU's they aren't easy things to repair.

 

[carbonzit]

when i tested the primary side of the transformer using a continuity testor there is continuity, but there is no continuity in secondary side of it!

Sorry if I sound doubtful, but are you sure that's a transformer? There are often things in SMPSs that look like transformers but are actually just single coils (inductors). Sometimes they'll have 4 or more pins like a transformer, but two of them are not connected and only hold the component to the PCB.

It's always possible, of course, that a transformer secondary could melt or go open, but it's very unlikely.