Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old September 18th 06, 08:34 PM posted to sci.electronics.repair
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Default 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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Old September 19th 06, 05:31 AM posted to sci.electronics.repair
isw isw is offline
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Default Zener diode color coding

In article ,
"Leonard Caillouet" wrote:

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
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Old September 19th 06, 12:27 PM posted to sci.electronics.repair
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Default Zener diode color coding


"isw" wrote in message
...
In article ,
"Leonard Caillouet" wrote:

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


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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Old September 19th 06, 02:50 PM posted to sci.electronics.repair
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Default Zener diode color coding


Leonard Caillouet wrote:
"isw" wrote in message
...
In article ,
"Leonard Caillouet" wrote:

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, 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.

www.techdata-kicksass.net

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


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