New Vector Monitor Project

Hi everyone!
I am looking forward to getting back to the new vector monitor design!

To refresh everyone's memory, here is a summary of what has been planned up to now:
Comments are requested.

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SUMMARY OF OVERALL DESIGN:
Design a new vector monitor using and adding to the electronics of an existing, NEW 19" WG raster display. The existing yoke will be removed from the tube, as well as the analog RGB drive wiring. These will be changed or reconnected to parts/boards of the new vector design. This design should be scalable, within reason, to vector monitor sizes other than 19"- for example 27" etc... Technically, a TV set could be used as well as a WG, but the physical chassis is a lot weaker, and more fragile, and the yoke would have to be another custom design.

The deflection board should be able to upgrade an existing vector deflection board, and I will try to include appropriate connections so it is versatile.

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HIGH VOLTAGE:
This will be a benefit of using an existing raster chassis - it already has this done.

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YOKE:
Yoke will have to be wound new. I found a place that is willing to do the job for about $50 a piece. Inductance on the X axis is about .9mH and Y should be about .6mH. Getting the geometry right will be challenging, but not impossible.

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DEFLECTION:
Deflection should be handled well by the LM3886 Power amplifier which is a sip package capable of high power analog audio drive! (This is a good find if I say so myself)

Protection circuitry is on board the LM3886
Total transistor failure (or shorting) would be handled by an in-line 3 amp fuse.

An approximate circuit diagram resides at
http://www.angelfire.com/nh/northamericantelecom/images/deflectionamp02.gif

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SPOT KILLER:
I was planning to using a charge pump on each axis to activate
a comparator. Upon activation of either output, each z axis
input would be pulled down to ground by it's own mosfet. (Of
course there will be a ~1K resistor between the mosfet and the
game board.)

Outputs active will light an led or two as desired. Spot killer
activation characteristics could be modified with resistor changes
or it could be made to be adjustable, if desired.

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POWER SUPPLY:
The power supply will consist of the following:

48V center tapped transformer
Bridge Rectifier package
2 Electrolytic capactiors rated at 6800 uF.
Some 0.47 uF caps for higher freq noise.

Dead simple, and should be good & reliable.

As far as regulation goes, there will be none. It should be unnecessary due
to the superior low frequency noise rejection characteristics of the LM3886.

I did find a good source for the 48V center tapped transformers.

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MICROPROCESSOR:

Daughtercard 0.1" header (dual row) on the motherboard connector consisting of at the minimum:

x-in --o o-- x-out
y-in --o o-- y-out
r-in --o o-- r-out
g-in --o o-- g-out
b-in --o o-- b-out
+v --o o-- +v
gnd --o o-- gnd
-v --o o-- -v

Now I want to think of a way to design the circuit so all we have to do is plug in the micro board. No soldering involved. Unplug it, and wow, it still works. Worst case, I have to have a simple upgradable analog daughterboard. This may be the most technically correct answer.

Clay will be doing the design of the microprocessor daughterboard! Here are some excerpts from his ideas:

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Ok. I can think of a variety of functions that would be nice and are handy to implement on a microcontroller. (The AVR's have onboard EEPROM which is kinda slick...)

1) smart and/or adjustable spot killer with variable stages of shutdown (guns off, defl. amp off, power off)
2) smart diagnostics (display quadrant of failure-- probably most pertinent to discrete designs)
3) Time in use/time since service (hour meter saved in EEPROM)
4) Temperature monitoring (use LM75 or something)
5) Fan control/additional cooling (either PWM or just a 2N7000 to click on a fan)
6) soft size/center control & front-panel controls (digital potentiometers on input op-amps)
7) presets for size/center (once again by EEPROM settings)
8) "Vertical in Horizontal" mode (digital pots automatically adjust display to a vertical aspect ratio on a horizontal monitor-- good for Tempest on Major Havoc or Tac/Scan in a StarTrek).
9) test display? (draw an "X" or something on the screen with a couple caps or PWM D/A?)

I agree that it might not be smart to burden the base design with the smart-functions. On the other hand, I think it would be fun to make the add-on available as an upgrade for extra functions... I could do a couple different versions too-- one that's "supervisor only" (spotkiller, temp monitor, time-meter) and one that has a remote-control board for screen adjustments from the front panel, BIST, etc.)

Any buttons, fan connectors, temperature sensors, etc. could be on another
connector on the daughtercard that goes to a remote control panel that you
could mount behind the coin-door or someplace easily accessable. (Since
I've got digital pots on the daughtercard the "remote control" board is only
digital so we don't have to worry about picking up noise or attenuating the
analog signals with a bunch of wiring...)

The shunts across the +v, -v, and gnd wouldn't be needed, but probably
should be included just for the sake of consistency.

I'd even pay for the connectors and shunts-- in order to be able to do a
daughtercard for it later. ;-) -Clay

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I hope this inspires everyone.

Comments are requested,

James

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Received on Wed Jan 12 16:17:19 2000