[SANYO DVD MODEL 7120] Doesn't start, psu with burnt ic and fuse but...

[Ragnar22]

Hello guys, this dvd player didn't start so I started checking the PSU as usual.
I checked a burnt IC3 and a blown fuse.
The thing is that I only found a similar schematic but not the exact one.(My PSU is 12PW2700PI-5 and I only found the 12PW2700PI-12).
The thing is that it's seems exactly the same, just needed some kind of info if I can thrust this IC3 to be a TNY267P.

Thanks in advance.

 

[betwixt]

It is almost certainly a TNY267P but before you replace it and the fuse, check for short circuits between each of the output rails and also shorts across the diodes in the transformer secondary. Anything like that will increase the load on the PSU and add extra stress to IC3. It would be worthwhile doing a simple DVM check of all the components given the simplicity of the circuit.

If you power it up - even if it doesn't seem to be working, be VERY careful of touching anything to the left of TR2/IC2 on the schematic as it will all carry high voltages.

Brian.

 

[Relayer]

Hello Ragnar22,
Since the fuse has blown quite violently, you may have many components that have failed.
Please see below modified schematic on the components that need to be checked regardless.
There's is a good possibility that the feedback circuit (around opto-coupler) has triggered a false
feedback voltage, causing an over current situation.
I would recommend you lift one leg on any of the diodes you want to check to ensure they are not leaky
by performing a punch-through test.
Since the supply isn't vastly complex, it wouldn't hurt to check any of the other components, especially those
in the primary side of the PSU.
Please take special note on Brian's comments, especially the main filter capacitors, as they can store a hefty charge.
You can discharge them using a 5 Watt 100 ohm resistor, this will discharge them without the sparks.
Please let us know what you find and how you get on.
Good Luck!!! :wink:
Regards,
Relayer

 

[Ragnar22]

Hi Relayer, thanks for the tips I will check that components and more on the primary side.

Last week before I saw ur tips, I checked the big diodes on the secondary and then replaced the ic and the fuse. When I turned on the PSU the fuse exploded and destroyed some components on the primary side.

I wil do a massive sweep on the primary side before I try again.