Datasheet for the 1N4933 fast recovery rectifier, saved as a 44.2 KB PDF whose name points to revision 3 of the document. The dx part of the name is unexplained and may be a vendor or document code. The 1N4933 is the lowest voltage member of the 1N493x series, used in fast switching rectification. The sheet helps a technician confirm forward current, surge and recovery time ratings before replacing a diode in a power stage. Any PDF reader opens it, and the marking on the original part should be compared first.
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.
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