NeXT
Veteran Member
The tiny CRT in a consumer camcorder is a fantastic piece of work. I also feel they are the most unexploited video displays you can get your hands on.
I always wanted to make use of the things but assumed that there was a bit more going on that you would expect. I was wrong. Give it power, give it video and it's okay. As seen above a cheap 9V cell is enough to drive the electronics and even more suprisingly the video signal in no way needs to be special. Just feed it composite.
The process of going from a camera to working on the bench is also really simple. If you have a DMM, a soldering iron, some wire and a battery you're all set.
Get yourself a camcorder, preferrably one that has seen better days. The key part you need is the viewfinder. Pull it apart and you should find the CRT and the analog board are a tethered two-piece assembly.
If you salvaged from one of the older VHS cameras where the viewfinder is a mirrored 90 degree assembly the analog board might share the space with the microphone corcuitry. For everyone else it will probably look like above. Lets comb out the essential connections. There might be one or two wire harnesses that connect the viewfinder to the camera which are also doing stuff like audio form the microphone or the REC led. Either unplug or desolder and remove them and we'll start here. In my case it was the connector marked "PG822".
We are looking for the ground, power in, and composite in. Start with finding the negative lead on a cap somewhere on the board, at best close to the former connector and with the Digital Multimeter in ohms poke at the pins on the connector until you find which one has a connecton to the negative lead. This will probably be your ground.
I recommend you mark where it is by soldering in a wire to that pin. I used a green wire as to easily identify it. Now we can determine what pin powers it.
If you have a bench supply I recommend you set it down to 3v and limit current to 200ma. If you are using the 9v battery you will be fine. What you are going to do is poke at the rest of the pins on your header to see which one powers the analog board. You don't need a lot of power so the chances of blowing something up are pretty slim here unless you do something reckless. You will know when you have the right pin when you hear the whine of the high voltage. For those using the bench supply it will be really faint but once you find it you can crank up to 5v which seems to be the minimum voltage these analog boards will work with. The ones I try with seem to behave right up until 12v but the current draw is incredibly minimal so you can probably keep it happy off a USB port.
Okay, so you now have power being fed and it appears happy. Now for the video.
I have done this to five other units so far and they all have been happy with composite video however I won't say that they all work like that. I'm pretty sure there are viewfinders out there that need an additional sync signal or something stupid off the camcorder. For composite the obvious key is that you connect the ground/shield of the device that is supplying the video to the ground on the analog board or you run into vertical sync issues or no image at all. Anyways, the process to find which pin is video is the same above. Poke at the remaining pins until you find which one gives you a picture.
As seen I used a red wire to indicate the positive lead for power and used a yellow wire for video. Once you have that soldered in you're pretty much done and you now have yourself a fantastic low power and portable 1/2" CRT display for your next project.
One thing to note is that if you pulled from a shoulder mounted camera the CRT image will be reversed because it's expecting a mirror. Reversing the horizontal yoke winding will correct this. (or something along those lines which immediately eludes me but it was a "swap wire A with wire B" solution)
I always wanted to make use of the things but assumed that there was a bit more going on that you would expect. I was wrong. Give it power, give it video and it's okay. As seen above a cheap 9V cell is enough to drive the electronics and even more suprisingly the video signal in no way needs to be special. Just feed it composite.
The process of going from a camera to working on the bench is also really simple. If you have a DMM, a soldering iron, some wire and a battery you're all set.
Get yourself a camcorder, preferrably one that has seen better days. The key part you need is the viewfinder. Pull it apart and you should find the CRT and the analog board are a tethered two-piece assembly.
If you salvaged from one of the older VHS cameras where the viewfinder is a mirrored 90 degree assembly the analog board might share the space with the microphone corcuitry. For everyone else it will probably look like above. Lets comb out the essential connections. There might be one or two wire harnesses that connect the viewfinder to the camera which are also doing stuff like audio form the microphone or the REC led. Either unplug or desolder and remove them and we'll start here. In my case it was the connector marked "PG822".
We are looking for the ground, power in, and composite in. Start with finding the negative lead on a cap somewhere on the board, at best close to the former connector and with the Digital Multimeter in ohms poke at the pins on the connector until you find which one has a connecton to the negative lead. This will probably be your ground.
I recommend you mark where it is by soldering in a wire to that pin. I used a green wire as to easily identify it. Now we can determine what pin powers it.
If you have a bench supply I recommend you set it down to 3v and limit current to 200ma. If you are using the 9v battery you will be fine. What you are going to do is poke at the rest of the pins on your header to see which one powers the analog board. You don't need a lot of power so the chances of blowing something up are pretty slim here unless you do something reckless. You will know when you have the right pin when you hear the whine of the high voltage. For those using the bench supply it will be really faint but once you find it you can crank up to 5v which seems to be the minimum voltage these analog boards will work with. The ones I try with seem to behave right up until 12v but the current draw is incredibly minimal so you can probably keep it happy off a USB port.
Okay, so you now have power being fed and it appears happy. Now for the video.
I have done this to five other units so far and they all have been happy with composite video however I won't say that they all work like that. I'm pretty sure there are viewfinders out there that need an additional sync signal or something stupid off the camcorder. For composite the obvious key is that you connect the ground/shield of the device that is supplying the video to the ground on the analog board or you run into vertical sync issues or no image at all. Anyways, the process to find which pin is video is the same above. Poke at the remaining pins until you find which one gives you a picture.
As seen I used a red wire to indicate the positive lead for power and used a yellow wire for video. Once you have that soldered in you're pretty much done and you now have yourself a fantastic low power and portable 1/2" CRT display for your next project.
One thing to note is that if you pulled from a shoulder mounted camera the CRT image will be reversed because it's expecting a mirror. Reversing the horizontal yoke winding will correct this. (or something along those lines which immediately eludes me but it was a "swap wire A with wire B" solution)