WG 15V2000 monitor display issues

Jakewd

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Hi everyone,

I am having a problem with my Wells Gardener 15V2000 monitor.

The monitor is out of an Asteroids Deluxe cocktail machine, I have verified the game board is working and displaying properly on an Asteroid Deluxe standup machine.

I have checked the voltages from the PSU to the monitor and they are correct and within range. I have also recapped both the Deflection and the HV board as well as reflowing the pin headers and most solder connections.

After I did this work, the monitor started outputting HV and I used a HV probe to adjust it to the correct voltage. When I plugged the game board into the machine and turned it on i heard defection chatter, but the monitor was not displaying an image.

After I turned up the contrast and brightness there was a haze in the right side of the screen and one of the power transistor (Q708) got very hot (burning fingers hot) and I shut it down. After buying replacement power transistors, the same one was getting hot so I decided to look over the deflection board for any burnt or broken components I might have missed, but I saw nothing out of the ordinary.

This is where I am stuck, nothing I've seen on FAQs mention this problem. I took a video of what happens to the monitor when turned on (https://drive.google.com/open?id=1FLkKyuqPh7n1PrXFCAjnJtKyEtMsLqEe).

Any help and suggestions are appreciated.

Thanks,
Jake
 
The nice thing about vector monitors is that the circuitry for the two axes is almost identical, so you can take readings on one side and compare them to the other to see where there are discrepancies. I would take the deflection board out of the monitor, then check all the transistors with the diode setting of your multimeter. For example, compare all six readings on Q601 (black lead on C, red lead on B / black on C, red on E / black on B, red on E // red on C, black on B / red on C, black on E / red on B, black on E) with the same measurement on Q701. They should be similar (but not necessarily exactly the same). If you find one that's different, it could mean the transistor is bad or a diode or other component connected to it is bad. If you get continuity (zero ohm short) across any legs, that transistor is bad.
 
Thanks for the advise douglasgb,

I've gone through and checked the transistor values as you've said and they all turned out to be the same values. Could there be any way to check the deflection board for bad components? Or does the problem seem to be coming from another part of the monitor.
 
Check D608 and D708. Also, test all resistors, especially the 1/4 watt ones. They can sometimes burn up but not show it (as they can burn on the underside, or the side facing another adjacent component).

These b/w deflection boards are all about details, as it's often something really small that is hard to see. Also check for cracked traces, especially where the traces meet the connector headers. Use your DMM to check continuity, not your eye.
 
Thanks for the response andrewb, I went through with my DMM testing resistor values and found a nice and crispy resistor (R713) hidden that had no continuity at all :) and Ive already gone and order a replacement resistor. I didn't see it at all since it was tucked away between C702 and Q504 and was blown on on the bottom portion near the PCB. Everything else has checked out okay.

One the replacement resistor comes in I hope to get this monitor back and running. Sometimes it's the smallest stuff that's easy to miss that makes the biggest difference even if it's only 27 ohms.
 
Yes, I know exactly which one you are talking about. It's hidden behind that fat cap, and is one of the ones that burns up when the transistors fry. I've been tricked by that one myself before.

Good find.
 
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