19 inch tv vector conversion

[AutogolazzoJr]

Alright, I recently acquired a samsung CXD1942 - it's a 19 inch crt tv. I think it would be a cool project to convert it into a vector display and play old atari vector games on it. Unfortunately I have previous HV experience, but that's about it. I don't have experience in arcade games or vector displays. I don't have the money and resources to buy a real arcade board. That leaves it to using emulation and specialized vector generators. I know the yoke needs to be rewound, but what will be driving it? What about color control? Can someone point me in the right direction? Thanks.

[james_s]

I would suggest starting by studying the schematics for the Amplifone and Wells-Gardner 19K6100 monitors, the manuals for these are readily available online.

In a nutshell since the yoke is inductive and the beam position is proportional to the current through the yoke, you need a voltage to current amplifier. If you look at the circuit you'll see that it resembles an op-amp, very high open loop gain which is tamed by negative feedback. Unlike a typical amplifier, the negative feedback comes not from the output voltage, but from the output *current* picked off the top of a sense resistor between the other end of the yoke and ground.

There is a guy I know named Fred Kono who designed a modern deflection board and pioneered the concept of rewinding raster yokes to make them suitable for vector displays. At one point he was selling kits for his boards so you could google his name and ask if he still has any. I have built a small vector deflection board for my 5" B&W vector monitor but I have not tried scaling it up.

Oh and don't neglect the spot killer, it's not absolutely needed for a little 5" tube but with a larger tube the beam needs to be hot enough that if you lose deflection it will instantly burn a hole in the phosphor. Anything from around 9" and up a spot killer circuit is mandatory.

[AutogolazzoJr]

I touched a screwdriver to the tube pins PCB after it was turned off and saw a little flash of light. Now the tv turns off quickly after it turns on and repeats. Perhaps a shorted capacitor?

[james_s]

I'd be more inclined to suspect a shorted semiconductor but it's hard to say. Generally shorting pins shortly after it has been on is not a good idea, as you've now found out why. Discharging the anode under the suction cup looking terminal is a good idea though before poking around inside.