CRT Viewfinder Hacking trouble??

[Sosijdog]

Hi guys,

I am trying to hack into an old viewfinder crt for a project. I have figured out the wiring for power in and earth and also video signal in. However the picture I get looks like a photographic negative! Whites are Black and vice versa!?

What have I done wrong? I have tried all the input pins for the video feed but only the one gives me any picture at all. Any suggestions as I am stumped?

Cheers guys.

Stevo.

 

[MAGNETRON]

Sounds like the video signal needs inverting,try a simple transistor inverter,then into the input.Trouble there is you may get correct video,but your line and frame sync may suffer?

 

[Sosijdog]

Thanks for the reply Magnetron.

I had a play around with it last night and found by adjusting the trimmer pots inside I got it to work right. The white was washing out on the screen so badly it looked like it was a negative!

However! I had it connected up to a 9 volt battery (like others have used online) and it worked fine for about 5 minutes... There was a barely audible high pitched whine shortly before it stopped working.
I must have burnt it out!

There doesn't seem to be any burnt components, but obviously something has gone. Any way to fix this? And what voltage should I be using? (I would like to run the viewfinder off batteries). It would be good to know so I dont burn out the next one I get!!

I am very keen to get this to work and I am sorry to bother all you Electronic Wizards with my newbie questions, but your help is greatly appreciated.

Thanks again,
Stevo.

 

[mneary]

You didn't mention if you tried another battery? My first suspect is that the 9V battery (250 mAH?) just didn't last very long.

Try to find out what the original camcorder used. Any make/model info?