The 2SK1375 N-channel field-effect transistor is covered by this 150 KB PDF, filed under schematics in the catalogue. Being a 2SK part, it belongs to the JIS-registered Japanese family of N-channel devices often found in power supplies, inverters and amplifier stages. The sheet should give ratings, thresholds and the pin layout of the package. Use it to test the device correctly out of circuit, to check for gate-drain shorts, and to confirm any substitute meets or exceeds the original limits.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @cyberlanelectonik. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.