Zener diode color coding

[Leonard Caillouet]

What are the conventions? Got one with a black stripe in the middle, red
stripe next on the end, then a red stripe on the leg. It is on the input
(pin 4) to gnd of a STRG6624 in a Panasonic PS. No schematics on this one.
This is the PT50LC14 that I was looking for the regulator type for. The
rated max on the input is 35v.
I'd guess 12 volts with a tolerance band but the input voltage seems to need
to be between 14 & 22 vdc according to the spec sheet for the regulator.
Maybe I'm reading it backwards and it should be 22.1v?

Anyone know how to read these?

Leonard

 

[isw]

What are the conventions? Got one with a black stripe in the middle, red
stripe next on the end, then a red stripe on the leg. It is on the input
(pin 4) to gnd of a STRG6624 in a Panasonic PS. No schematics on this one.
This is the PT50LC14 that I was looking for the regulator type for. The
rated max on the input is 35v.
I'd guess 12 volts with a tolerance band but the input voltage seems to need
to be between 14 & 22 vdc according to the spec sheet for the regulator.
Maybe I'm reading it backwards and it should be 22.1v?

Anyone know how to read these?

The color code on a Zener doesn't tell you the voltage; it'll be the
three or four digits after the "1N" in the part number. And a precision
of 0.1 volts would be quite unusual at 22 volts. Maybe around 6.5 volts,
as there's a "sweet spot" there that gives near zero temperature
coefficient of voltage.

Why don't you stick a limited current through it, and measure it?

Isaac

 

[Leonard Caillouet]

The color code on a Zener doesn't tell you the voltage; it'll be the
three or four digits after the "1N" in the part number. And a precision
of 0.1 volts would be quite unusual at 22 volts. Maybe around 6.5 volts,
as there's a "sweet spot" there that gives near zero temperature
coefficient of voltage.

Why don't you stick a limited current through it, and measure it?

Isaac

There is no number, only the color codes. The diode is shorted and I need
to know the value to replace it. Tried 22v since that is the upper limit of
the chip and it runs fine, but there are problems in the signal processing.

Thanks for the reply.

Leonard

 

[Tech Data]

Leonard, didn't see this post before. I would think that it's a 'gate
protect' zener for the regulator and they are usually no higher than
18volts.

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