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The Vectrex is a vector based video game console that was developed by Western Technologies/Smith Engineering in 1982.

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Vector display has collapsed into a single vertical line.

I found a Vectrex for 10 bucks at a local swap meet! Score! But wait, it can't be that easy right?

When I fire up the unit the Vector display has collapsed into one single vertical line in the center of the Screen. This would seem to indicate that the beam emitter is not drawing vector lines on the X-axis.

I've done some research and found this service manual online and trouble shooting guide online:

I've cracked the system open and reseated all of the ICs as the trouble shooting guide indicated that the sort of trouble I was having might be related to "IC Creep". I'm not that technically inclined, so maybe somone here can take a look and come up with some additional suggestions.

Any ideas?

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Finally got around to cracking this baby open again and adjusting / cleaning the potentiometer. No luck. It's really too bad because I found a copy of scramble over the weekend and was really hoping to get it up and running on the old girl.


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Soluzione Prescelta

First off, A little SAFETY message since this console has high voltage present in it.


Working on equipment with CRT high voltages can be FATAL. YES, FATAL. Be sure to know where the danger area is located on your equipment and take precautions to avoid electrocution and/or shorting out the high voltage supply. Avoid wearing anything conductive (watches, rings, bracelets) and be sure to use insulated tools to protect against unintentional electrical shock. I take no responsibility for injury resulting from trying to troubleshoot your equipment based on my recommendations in the response. YOU HAVE BEEN WARNED.


Tools needed for this repair:


  • A copy of the schematics (already provided by the requester )
  • An oscilloscope (strongly recommended)
  • A non-conductive screwdriver for the X Size deflection potentiometer
  • A voltmeter

Troubleshooting your Vectrex issue:


The quickest thing to check is to see if you are getting horizontal deflection signal from the game board before it reaches the monitor. This is on PIN 1 of IC302. If you don't have signal, there is DAC problem (not covered by this response). If you do have signal, the steps are to use a oscilloscope probe while tracing the signal to its eventual output at the deflection yoke.

Take a look at the posted schematics. (specifically pages 33 and 35). Based on you information, the following components are in the signal chain until the output at the X Deflection Coil.

IC305 (pins 11 input, 10 output) -> IC303 (pin 11 input, pin 14 output) -> x-size potentiometer -> Q402 JFET (pin S in, Pin D out) -> IC401 (Pins 8,9,10)

Possible bad news


If you have signal all the way to the output, the worst possible scenario would be if the deflection yoke was burned open. If this is what happened, you are going to need to part out another dead Vectrex to source a new monitor yoke - or just do a monitor swap from a donor machine with a dead logic board. Getting small X-Y black and white monitor yokes is going to be impossible unless you find someone to wind them up for you. (EXPENSIVE)

There is hope


On the bright side of things, it could be something as stupid as cleaning the X-Size potentiometer. These can die just from dirt/dust. Cleaning them with potentiometer spray (WITH THE UNIT OFF) and a small bristle brush could instantly fix the issue. Do NOT use WD40 - use something that is engineered specifically for potentiometers. A way to quickly investigate if this is a problem area is to tap on the potentiometer with something non-conductive and see if the deflection jumps around. If it does, then it's an EASY fix solved with a simple cleaning job.

1) UNPLUG you game and let the power supply fully drain for 30 minutes - 1 hour.

2) Mark the set position of the potentiometer with a sharpie so you can return to the factory setting after you clean it.

3) Spray and brush as much junk off the potentiometer as possible. 4) Take a small screwdriver and rotate the knob through its full rotation in both directions 5 - 10 times.

5) Return the potentiometer back to its setting you marked with the sharpie marker,

6) wipe off any excess cleaner spray with a paper towel, and let any excess liquid thoroughly dry out.

7) power on the game, and see if the problem is fixed.



If the potentiometer was the issue, and you have decent desoldering/soldering skills, i would strongly suggest replacing it with a modern equivalent. They are cheap and will be a significant improvement over the original part.

Good luck to you and hopefully it's not a dead deflection yoke.


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love the response - in fact, detail and humour (it was humour, yes?)


Wow! Thanks for this amazing response! I was a little worried that Vectrex might be too old a system.

Looks like I'll need a voltometer and an oscilloscope. I've seen lots of warnings on other forums about the shock hazard so I've been especially careful, especially given that I'm a total n00b in terms of electrical engineering. I've had the thing unplugged for about three weeks so hopefully it's not still carrying a charge, but I'll still exercise caution.

Thanks again.


I'm a big fan of vector games, and have repaired full size arcade vector machines for about 10 years (Atari, Cinematronics, Sega). The Vectrex is the same concept. 90% of the time the failure is power supply caps, a blown deflection transistor, toasted DACs, or in rare cases a fried yoke. Some vector game circuits are defective by design.

Do some googling and you can find a group that has a multi-cart with all of the Vectrex games burned to one cartridge. Serious collectors want all the overlays and carts, but for the "player" the multi-cart is a must have.

Good luck to you - hopefully it's just the x-adjustment potentiometer.


I realize this is 5 years old, but I had to reply. Tekonhed, You said you had the unit unplugged for 3 weeks. Those caps can hold the charge forever. You have to discharge them (I don't know how). Just thought you'd like to know.


@Rob Ricci, you discharge the capacitors just like any other cap. Put a high value resistor (100-200K ohms) across such capacitors to bleed them down


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check the power capispater sounds like a bad cap

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Using a 10Mohm resistor,discharge each lead of a HV cap individually to ground, then between the leads,.

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I think it's an issue of the crt-tube. There should be a PCB at the end of the tube, try to resolder its pins.

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Something wrong with a coil?

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teknohed sarà eternamente grato.
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