Crystal diode replacement - Videokarma.org TV - Video

classicradios · #1 12-22-2002, 09:34 AM

Hello,
I need to replace a diode on a Zenith Porthole chassis I'm working on. It's identified on the schematic as A-1(1N64)
Zenith part# 103-1 Description: Crystal diode 1N64
It's chassis 23G24. Does anyone have a source for these diodes or some type of a substitution part?
Thanks
Jim

Tom Bavis · #2 12-22-2002, 11:20 AM

I suppose a general purpose germanium diode would work - like NTE109. I'd probably use a Schottky diode like 1N5711 (18 cents from Mouser) if I didn't find the right one in my junk box. I know I have some 1N34 old style parts if you want one - don't know about 1N64.

Charlie · #3 12-22-2002, 12:37 PM

They have general purpose and rectifier diodes at your local Radio Shack. Just make sure you get at least the amperage requirement that your schematic calls for. Most of RS's diodes are 1 or 2 amps, so you should be able to find one there that will cover your application.

kc8adu · #4 12-23-2002, 05:36 PM

that is the video detecter.
radioshack may have 1n34.
power rectifiers probably wont work well.
if you strike out i have some here and can send you a few.

classicradios · #5 12-23-2002, 06:02 PM

Is that why I'm getting negative voltage readings on the 2 6BN6 tubes? All resistors and replacement caps test OK.
Jim

kc8adu · #6 12-24-2002, 08:05 AM

i dont have the schematic here so its hard to say.
did you do a ohmmeter test?
think of the diode as a one way street for electrons.
should be very high resistance or open one way and low the other.
if it is bad you would likely have no,weak,or maybe smeary video.

classicradios · #7 12-24-2002, 09:28 AM

At the present time, No Video only Raster. Changing channels has no effect either. Audio is also out, Only a constant hissing or buzzing noise from the speaker. The sound volume increases with a clockwise turn of the vertical size control. Guess I'll have to replace the diode before I go any further and see where I'm at.
Jim