Film-Tech Forum ARCHIVE: ORC 1000 Console zener diode

This is topic ORC 1000 Console zener diode in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Phil Housh (Member # 1721) on 05-07-2007, 08:35 PM:

Does anyone know the value of the zener diode that is in the auto ignition circuit on an old ORC console? I have the circuit diagram, but can't find the value. I also looked here on Film-Tech, but can't read that one either.

Thanks!

Posted by Mark Gulbrandsen (Member # 72) on 05-07-2007, 08:40 PM:

Try looking on the diode itself.... Probably a 1N#### or MZ#### somethong or other number...

Posted by Phil Housh (Member # 1721) on 05-07-2007, 08:47 PM:

Hi Mark,

Can you believe it, I have three consoles, but the number is not clear enough to read on any of them even with a lens!

Posted by Mark Gulbrandsen (Member # 72) on 05-08-2007, 09:44 AM:

Send me one and I can test it on my Tektronix curve tracer for you and tell you what voltage it is....

Mark

Posted by Dave Macaulay (Member # 813) on 05-08-2007, 10:48 AM:

If you know the autostrike relay coil voltage and the open circuit rectifier voltage then you can pick a zener voltage that will work. If it's a 24V relay coil and your rectifier has 100V open circuit then a 75V zener should work fine, or a bit lower.
If you have a working zener (out of 3 I hope so) it's easy to measure. Just get a 5K or so resistor and attach it in series with the (disconnected) zener across the rectifier output, use clipleads or something - NOT your hands, 100+ volts DC can kill you easily.

+_____________|<____________~~~_____________-
rect pos diode resistor rect neg
^ ^
measure voltage here

The voltage across the diode will either be around 1 volt or 50-80 volts. If it's 1 volt, reverse the diode connection and measure again.
Then just get a correct power rating zener - probably 5 watt -with a zener voltage specification close to the measured one.