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Bus Loads M8320: Replacement for diode D664
- Thread starter 4n6
- Start date
AK6DN
Veteran Member
My DEC replacement parts notes indicate a D664 can be replaced by a 1N3606 (older and hard to get) or a 1N4153 (still available from many sources).
vrs42
Veteran Member
Most uses of D664 do not seem super critical. Most signal diodes are probably close enough.
(Not "in spec" mind you, but good enough.) Your mileage may vary if you are fixing "S" or "B" series modules. (For those, I'd consider a Schottky diode, which will be "off spec" in a direction more favorable to the noise margin.)
Most uses of D662 are dependent on the forward voltage drop. That's often not well specified for modern diodes, and when it is, the curve doesn't match the D662. Also, I've encountered cases where it should match, but the actual diodes I received did not. (Everyone seems to feel that "small signal diodes" are generic.)
As a result, I find I sometimes need to add a a diode in series when building -3V clamps out of generic switching diodes. The generic diodes are probably good enough to replace one of the diodes, but if you replace them all the clamp voltage will be rather off.
Hope this helps!
Vince
(Not "in spec" mind you, but good enough.) Your mileage may vary if you are fixing "S" or "B" series modules. (For those, I'd consider a Schottky diode, which will be "off spec" in a direction more favorable to the noise margin.)
Most uses of D662 are dependent on the forward voltage drop. That's often not well specified for modern diodes, and when it is, the curve doesn't match the D662. Also, I've encountered cases where it should match, but the actual diodes I received did not. (Everyone seems to feel that "small signal diodes" are generic.)
As a result, I find I sometimes need to add a a diode in series when building -3V clamps out of generic switching diodes. The generic diodes are probably good enough to replace one of the diodes, but if you replace them all the clamp voltage will be rather off.
Hope this helps!
Vince
!