"Michael Kennedy" wrote in message
...

Is that black stripe a genuine paint one on the outside of the diode, or
a
Yes I believe it is genuine paint. It is on the other diode which has not
failed.. I guess I could find out what kind of zener diode it is by
testing it as you said, but I have never done this before.. I guess it is
time to learn.

Here is a picture of the working diode (ZD2 not ZD1) up close and in the
sun so you can really see the colors..

http://mikescomputers.homeip.net/LCD/DSC00386.JPG

Close-Up

http://mikescomputers.homeip.net/LCD/ZD2.JPG

Thanks,

- Mike


OK. Looks like a genuine paint band. I'm still up for it being 8V2 though,
if for no other reason than it's a very common value, and corresponds to the
other two stripes. If what ever the unit is, is working at all, then just
check the voltage across the non-blown diode. If the unit is not working,
you can test the other diode for voltage rating easily enough, by removing
it from the board and hooking a resistor - say 4k7 - to its cathode. Then
put 12v across the combination, "+" to the free end of the resistor, "-" to
the diode's anode, then measure the voltage across the diode. Any reading up
to about 11v, will be the zener voltage. If you get a reading of 11v or
more, then the diode hasn't 'zenered' and you need to up the voltage across
the combination a couple of volts at a time, until you do get a steady
voltage, that doesn't increase any more, as you continue to up the voltage.
You've then found the diode's zener voltage.

Arfa