Help identifying glass diode?

[Sam Goldwasser]

I'm no electronics professional, but mW rating is maximum power dissipation.
I think I could use a 10W device here and I'd still get 18v out of it, no? I
leave the "pushing enough current" to the circuit designers.

How much current is needed depends to some extent on wattage. So,
a low wattage diode will need less current. I doubt it matter much though
since it should never see anywhere near the rated voltage in this
application.

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[John Fields]

I'm no electronics professional, but mW rating is maximum power dissipation.
I think I could use a 10W device here and I'd still get 18v out of it, no?

---
Probably Not.

The Zener voltage is specified to be within the error limits defined
in the specifications when the test current, Izt, is flowing through
it, and the IZT for a 10 watt device will undoubtedly much greater
than the Izt for a 1 watt device.
---

 

[legg]

I'm no electronics professional, but mW rating is maximum power dissipation.
I think I could use a 10W device here and I'd still get 18v out of it, no? I
leave the "pushing enough current" to the circuit designers.

Replace using as similar a device as is possible.

A 400mW device will fail reliably and predictably, under single fault
abnormal conditions, as determined by the designer and relevant safety
agencies.

Other higher powered devices may not.

RL

 

[legg]

Fairchild semi's data sheet now in hand.


Diode is shorted in both polarities. Vacant position is relatively high
impedance (10K ohms).

You should now check the power device to ensure continuity on it's
terminals, through the device, and svice function, if possible.

The terminal connecting to the shorted zener location has likely gone
open circuit internally, unless another series element has done so
first.

RL

 

[Franc Zabkar]

Based on the lettering alone, could it be a 1N918, which happens to be
somewhat similar to a 1N4148?

Are you thinking of a 1N914?


- Franc Zabkar