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Zener diode color coding

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

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Reply to
Leonard Caillouet
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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

Reply to
isw

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

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Reply to
Leonard Caillouet

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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