This part is a kind of semiconductor called MR1721.

Function of this product has Partial Resonance PS IC.

Manufacturers : Shindengen Electric

Image and pinout :

Some of the text within the PDF file :

Vol.02-05-e / June2002 MR1000 Series Standby-compatible Partial Resonance Power Supply IC Modules Masaaki Hayashi - Electronic Device Div.Group Advanced Power Products Div. Device Design Dept. Assistant Manager (Joined the company in 1989) 1 Introduction Energy conservation guidelines from the Ministry of Economy, Trade and Industry’s Agency of Natural Resources and Energy place considerable emphasis on reducing standby power consumption of domestic electrical appliances. These guidelines designate domestic electrical appliances as 'special devices', and set target years and criteria for achieving these reductions based on the 'top runner' system. They are characterized by a considerable degree of severity in that, if targets cannot be achieved, manufacturers are l [ ... ]

MR1721 PDF Datasheet Download