Idenitfy this diode

[71cudalover]

I'm trying to do some repairs on a circuitboard with a number of IRF450 mosfets which have become shorted to gate and taken out some neighboring components.  I have some diodes on the board that I am trying to identify.  They have number 59 on them and a logo with a solid triangle and an open ellipse passing through them.  It shares some similarity with Vishay in the proportion of the triangle.  The cathode is marked with a double band with one of the bands being slightly thicker than the other. Someone else has done some repairs to this board previously, successfully, and used some that are marked with a number 76 and 3K400 it almost appears that these have the letters ISC printed in the cathode band.  The body is about 5 mm in diameter.  This is of Japanese manufacture circa 1989.

Does anyone recognize these.

[T3sl4co1l]

Old Vishay logo I think??

"3K400" *might* be something like a 3kW peak, 400V TVS diode.  But it could also be a UF5404 sort of thing (3A 400V, high speed -- just guessing from the general nature of the circuit?).

"59" could be anything.  BYVxx comes to mind, but I have almost no familiarity with those.  "Insert prefix here", anyone's guess...

Can you trace the circuit and see how it connects?  It's usually more obvious what the components are for when you see them connected.

Tim