12v/5v power supply -no power out

[playit]

hello , i use this adapter only for a case fan ,it ran for like 10 days , until today, i opened it , looks like a blown fuse , other than that i am not sure what else to check out , but i have tried to see what are shorts with a multimeter

at back -both 514 doesnt give me any reading or beeps(continuity) ,but if i keep at end of one 514 to other opposite end of other 514 - it gives me beep- continuity . other resistors are giving me readings , but please do tell me what should i check , i might have missed a lot .

at front - at the plug in - at side of c2 blue capacitor - the d2 is shorted , other side d4 is shorted the fuse doesnt give continuity , the ceramic broken like resistor gives a reading, its not shorted the 3 points of mosfet which is attached to heat sink aluminum at back gives continuity beeps . the capacitors all give readings except that green small capacitor , other diodes are ok
other than this please guide me what else should i do before replacing fuse and other stuffs, thank you .

[playit]

Re: 12v/5v power supply -no power out

the pics are attached now

[stj]

Re: 12v/5v power supply -no power out

i see no pics.
desolder the mosfet and rectifier diodes and check them all for shorts

[CapLeaker]

Re: 12v/5v power supply -no power out

I don’t see any pics either. Good high resolution and straight shot pictures are the key.

[playit]

Re: 12v/5v power supply -no power out

sorry i was uploading the pics and i lost the power , will be uploading it now

[playit]

Re: 12v/5v power supply -no power out

pics here now

[stj]

Re: 12v/5v power supply -no power out

mosfet has shorted and blown the safety resistor and probably damaged the mains rectifier diodes.
also burned a resistor on the track-side

[petehall347]

Re: 12v/5v power supply -no power out

looks like c3 fell off

[CapLeaker]

Re: 12v/5v power supply -no power out

If the mosfet is shorted on all three legs, you also got to inspect the gate drive circuit.

[playit]

Re: 12v/5v power supply -no power out

looks like c3 fell off

c3 is at back, looks like its moved , but it gives reading 175

[playit]

Re: 12v/5v power supply -no power out

If the mosfet is shorted on all three legs, you also got to inspect the gate drive circuit.

please guide me where to check what , thank you

[playit]

Re: 12v/5v power supply -no power out

mosfet has shorted and blown the safety resistor and probably damaged the mains rectifier diodes.
also burned a resistor on the track-side

is this due to long time running of this adapter , or due to more power surged through it ? thank you for responses

[stj]

Re: 12v/5v power supply -no power out

it failed because it's junk.
i throw stuff like that in my parts box usually.

[playit]

Re: 12v/5v power supply -no power out

it failed because it's junk.
i throw stuff like that in my parts box usually.

can i give some extra protection , make the junk little better, i just plan to use it for case fan

[stj]

Re: 12v/5v power supply -no power out

the problem is the build quality,
tiny fuse, poor construction.

if you want to fix it then start by removing the fet and rectifier diodes and test them off-board.
then test the main smoothing cap because it could have failed first and caused this.

your biggest challenge is going to be finding out the values of the 2 burned resistors.
and you need to check all the stuff on the trackside too.

[playit]

Re: 12v/5v power supply -no power out

smoothing cap means the c5 green 50v 4.5uf ? and about the resistor which gives continuity beep is 514 smd at back side 510 kΩ . please point out the names with colurs in the pcb in pic if i have missed anything , thank you

[stj]

Re: 12v/5v power supply -no power out

no, the mains smoothing cap - probably 47uf 400v

[playit]

Re: 12v/5v power supply -no power out

oh the bigger ones , mm it reads well ,some readings come and disappear like other capacitors . i will remove those resistors and rectifier diodes ,mosfet 2n70 and be back to update, thank you

[playit]

Re: 12v/5v power supply -no power out

at back of pcb there is q2 and q3 , how to check it , q2 gives continuity beeps on both pins , i am not sure whats it, how to check it , please guide me , thank you.

[stj]

Re: 12v/5v power supply -no power out

if any part looks suspicious on your meter, remove it and test again.
because it could be caused by something else on the board connected with it.
that is why i said to remove the mosfet and diodes