"John E." wrote in message
obal.net...
Ah, another ITT diode on the board starts with "ZY" (where "Z" could be
mistaken for a "4" on the charred carcass). So I looked up ZY47 and get a
4.7v power zener diode, 2W.

http://www.allcomponents.ru/diotec/zy47.htm

Also, according to a National data sheet I found, a 1N4147 (a.k.a. 1N914A)
is
glass, and way too lightweight physically compared to my charred sample.
Wrong turn, I think.

So it looks like ZY47?
--
John English

John
You can't just guess at this. As sue suggested, you need to look at the
circuitry and figure out what that diode function is. What is the circuit
for? What components are near the diode? Can you trace the diode connections
to the next devices? What are they? Once that is determined, there are
likely substitute devices that will work just fine, even if you can't
identify the original. I do this all the time as I restore a lot of old test
equipment. It can be a challenge when you don't have the schematic, but
generally you can get there with enough patience and logical thinking.

Ben Miller

--
Benjamin D. Miller, PE
B. MILLER ENGINEERING
www.bmillerengineering.com