The 1T404 code is all the name reveals about this 52.4 KB PDF, which is listed as a schematic. No device, maker or board number is stated. It most likely documents a single discrete component, with pinout, package outline and electrical data, rather than a complete circuit. Read it in any PDF program. It is useful for verifying orientation, comparing measured behaviour with specified values, and identifying a replacement. Note that a separate 1T404A variant exists, so check the suffix on the part.
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.