G'day all.

Hoping someone can help with the power supply in a NatPanasonic M12H (I think)

It's got a STR456a SMPS IC (I assume) in it that I've never seen before. I'm guessing the different IC model numbers denote a different HT output?

I can't find a circuit for this set or any specific info on the STR456, although I've found out a little about similar STR & STK versions.

It's a TO-3 style package but with three pins. It's shorted in all sorts of directions (which probably means I'm dealing with a bigger problem) but, before buying one, I'd like to know how it works. They are available but they're priced higher than the "lets put in a new one and see if smoke comes out" repair technique.

I'd love to be gifted a circuit for this set!

Yes, it's old. Yes, it's obsolete. Yes, it needs a digital converter and modulator to show a picture. I still want it to work because ..... well, just BLOODY because!!!!! (-:

P.S I'm not a technician but I know enough to avoid electrocution!

Did you try WES for the part?

If it's on a big heatsink it might be a linear reg. A suitable power mosfet and a few other parts could replace it in this case.

What is the model number of the set?
I might have the service manual/circuit description for it.

Wayne.

STR456 turned up in google. There was no datasheet, but a schematic showed it to be a power regulator for a switchmode power supply.

Pin1 - input (in this schematic, 220 volts)
Pin 2 - control
Pin 3 - ground
Pin 4 - output (in this schematic, 113 volts)

220 volts from the mains get rectified in a bridge, then through a winding of a transformer, and the other end of this winding goes to pin1 above.

Seems it's available for about $20 from a number of suppliers.

A bit off topic, but seems the schematic used by a supplier came from a site with what appears to be massive amounts of info on CRT colour TVs.

http://obsoletetellyemuseum.blogspot.com/