Help identifying mosfet

[David60639]

Hey guys, I bought an old oscilloscope on CL that did work and found 2 burnt mosfets. Google was not much help with the part numbers. Any help is much appreciated.                       

[ColeLamothe]

Not having much luck with just the chip. What is the make/model of the scope? it may be easier to track down an old parts list or schematic with that information.

[WattsThat]

They are not mosfets, the are unobtainium bipolar Tektronix parts in a 22xx series scope. 100% custom, no 2N numbers for those puppies. Early production model too, second week of 1987 for the transistors, they added heat sinks later on.

Why makes you say they are fried? Have you looked at the schematic? There are two diodes in the circuit that can make the in-circuit readings look odd. Don’t remember exact what it is but can research it if it matters. What are the symptoms? Any lights at all? Totally dead?

More info required.