Space Duel Resets When Monitor Connected

Michael Roma

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I finally got around to working on a SD I picked up many moons ago. It had a 6100 with blown f100 and f101 fuses. I rebuilt the monitor with Bob's deluxe kit. I put the monitor back in the game but did not connect the power to it. I power the game on (w/o the monitor connected) and get good voltages at the game pcb and it coins up and plays. I power down, connect the monitor, and power back on. The game acts like it is trying to start and I see the led on the game pcb flash dimly every second or so and the spot killer is not lit.

Any ideas? Am I looking at an issue with the vector generating section of the game board or a monitor issue?

Thanks...

- Mike
 
Does the PCB look like it's been hot at the connector? I would consider repinning the ground and power split pins in the edge connector.
 
The voltages are spot on at the game pcb w/o the monitor plugged in.

The voltages fluctuate too rapid when I plug the monitor and try to get a reading as the game is in a constant reset.

I have a couple of spare non-working boards that I swapped in. Without the monitor connected I get a solid red led on the game board. Once I connect the monitor it does the same reset routine.

So I guess I am looking at a monitor or transformer issue, right? Any thoughts?

- Mike
 
Have you re-checked your voltages after plugging in the monitor?

For what ever reason, something is pulling your power down when the monitor is plugged in. I would check your monitor board and make certain all electrolytic caps are in the right way. Use meter to check for shorts.

It is a power problem and you have narrowed it down to the monitor board so that is where I would look.

Could be transformer but I really don't think so, usually after transformer.
 
The monitor inputs could be dragging the 5v supply down(Id suspect through the Z inputs) or causing some kind of ripple on the 5v. You could try unhooking various parts of the monitor and see if one particular part is hosing it. It could be a failing big blue also, that the additional load is pushing it over the edge.

Andrew
 
Update...

So I plugged the monitor up but unplugged J100, J600, and J700. Powered on and it did the reset loop. What does this rule out and what sections/components are left that could be the cause?

- Mike
 
Plug everying into the deflection. Leave the power and video input off of the HV cage. Power it up. you should have no spot kill led on and the tube is dead. If all it OK then test with power and video to HV cage. if the problem presents itself you have a problem in the HV cage.
 
I swapped out the big blue and get the same reset issue. So now it's looking more and more like a probable monitor issue.

So I have J100, J600, J700 on the deflection board disconnected and P900 and the power disconnected to the HV cage and the game goes into it's reset loop.

What could it be?

- Mike

***mods, please move to the monitor repair section. Thanks***
 
I had some time this afternoon to look at this further...

I unplugged the three wire molex connector in between the transformer and 15 pin connector that plugs into the monitor. I put the probes in the brown wire's connectors, powered it on, and received 50VAC (which is what the game manual calls for). Then just for SnG I powered the game down and tested for continuity between all three wires (two browns and a grey)... they're all shorted. I figured that was strange as I would have thought the grey wire would be ground. I then check the schematic for the WG6100 and see that pins 13 thru 15 are the power connections that are fed from the transformer thru this intermediate molex connector. I also notice that it says 25V RMS and the wire that is fed from the grey wire is in fact ground.

So, did I just confirm that the transformer is shorted??? What is the deal with the 50VAC coming out of the transformer and then 25V in thru the connector??? There is nothing in between except for the quick disconnect molex to draw the voltage down.

Here are the excerpts from the manuals...

- Mike

SD_WG6100Questions.jpg
 
Well... since a transformer is just wire, the multimeter will read a short. That's normal (actually, if you check the actual resistance, it should be a little higher than dead short... a few ohms or so). The reason for the difference between the 50V and 25V is that you have 50VAC, with a center tapped transformer (that's what CT means). This gives 25V on each side relative to the center tap. That's similar to house wiring, with two hots and neutral.

What happens if you turn the game on without the 3 pin connector plugged in? Also, when it does reset, what's the +5V read? If this is low, check farther back... input voltage to the A/RII, etc. Also, check all your fuses to verify that none have increased in resistance (all should be under 1 ohm).

DogP
 
At this point, I'd pull the RGB and XY input pins out of the connector and see if the problem persists.

The idea is to power the board AND the monitor at the same time and see if it keeps resetting.

If it still resets, then nothing is pulling down the signals and causing any glitch through the PCB output pins. It would have to be on the power supply side then.

And yes, your transformer is NOT shorted. If you're getting 50V center tapped output, then it's good.
 
Did you check your deflection transistors... the ones plugged into P700? Might as well check them all while you're at it.

DogP
 
I ended up sending the boards out to KLOVer mcandrewsoun for repair. Here is his repair log.

4700mf 50v cap was bad, and that was causing the 2 diodes & fuse to blow. The regulator on the -34v supply was also dead. The screen voltage wire (red wire on neckboard) needed to be re-soldered. I hooked it up to my frame and everything worked.

I also had several bad transistors again on the monitor frame that I replaced before reconnecting everything and powering on. Game has been running like a champ since. I would PM mcandrewsoun and see if he is still accepting work. It was priced well, the work was excellent, and the turnaround was fast.

Good luck.

- Mike
 
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