Get one from the same type of supply or just rewind it in exact way with the same size wire.

 

Yeah the photos are terrible. You need to set your camera to "macro" setting and use a bright light.

Why did you remove that transformer? With so few turns (and thick wire) it is extremely unlikely to have failed. You can test ohms to see if it is shorted between winding, but I really doubt it will be.

What about the solder joints I mentioned in post #14? After the caps the next most likely cause of a heat fault are the solder joints on the power components, which you need to inspect with a magnifier. After that you start replacing power components.

Do you have any test equipment?

Did you test it with a load attached?

 

suppose it is burned how to replace it???mh??

If it has more than one winding, burned enamel is pretty much guaranteed to allow shorts between windings.

Rather than try to identify the core material for replacement - its probably better to try rewinding it - do a *VERY* detailed sketch to show the sense and position of each winding.

 

Yeah the photos are terrible. You need to set your camera to "macro" setting and use a bright light.

Why did you remove that transformer? With so few turns (and thick wire) it is extremely unlikely to have failed. You can test ohms to see if it is shorted between winding, but I really doubt it will be.

What about the solder joints I mentioned in post #14? After the caps the next most likely cause of a heat fault are the solder joints on the power components, which you need to inspect with a magnifier. After that you start replacing power components.

Do you have any test equipment?

Did you test it with a load attached?

only testing equipment is multimeter....when i checked solder joint i found this coil is dislodged as if solder joint has been melted...i take it out because some turns of coil seems to be dark brown... and to take phot of it...only this clarity is available ...my cam (2mp)do not have flash (will try to take it in sunlight)....

heatsink and respected components soldering checked...no problem but its solderpaste seems to be spread around it...

load is my motherboard when i connected same as above.. worked for less than a second...

 

If it has more than one winding, burned enamel is pretty much guaranteed to allow shorts between windings.

Rather than try to identify the core material for replacement - its probably better to try rewinding it - do a *VERY* detailed sketch to show the sense and position of each winding.

That's just dark brown varnish it is dipped in. We used the same murky dark stuff in a motor rewinding shop I worked in.

Those toroid transformers don't blow, they are used to generate a low power secondary voltage rail, often the -12v rail. The main SMPS transformer is the big yellow ferrite block one in the middle of the PSU.

 

That's just dark brown varnish it is dipped in. We used the same murky dark stuff in a motor rewinding shop I worked in.

Those toroid transformers don't blow, they are used to generate a low power secondary voltage rail, often the -12v rail. The main SMPS transformer is the big yellow ferrite block one in the middle of the PSU.

ok...now i reconnected coil and checked all solder joints....now it works....but o/p voltage at blue wire is -10.86V instead of -12v..

@ 12v i get b.w 11-12v range (<12v)
@ 3.3v ---3.06v
@5v ----5.86v

shall i connect to PC????

 

ok...now i reconnected coil and checked all solder joints....now it works....but o/p voltage at blue wire is -10.86V instead of -12v..

@ 12v i get b.w 11-12v range (<12v)
@ 3.3v ---3.06v
@5v ----5.86v

shall i connect to PC????

Some of those voltages are a bit off - calculate how many % off they are.

Its nothing unusual for 12V rails to be a bit low - especially the negative one.

Usually, the regulator takes the 5v & 3.3V rails into a network of summing resistors, so they can be a bit off if not properly loaded.

You can make a dummy load for testing with various auto bulbs - the 2 filaments of a H4 headlamp bulb for 5V & 3.3V, a 21W indicator bulb for the +12V and 4W dash bulbs for everything else.

If everything properly loaded comes within 10% of what it says on the tin, its probably OK.

 

THANKS

ok...thanks for all guys for replying for my thread...helped me great...

alfacliff
THE_RB
R!f@@
ian field

 

...
@ 12v i get b.w 11-12v range (<12v)
@ 3.3v ---3.06v
@5v ----5.86v

shall i connect to PC????

If that is running with no load, those voltages are fine. The 5v rail is high because it is struggling to regulate with no load attached, and the other rails are low because the duty cycle is cranked right down (because it is trying to regulate the 5v).

Connect to the PC and measure the voltages then.