Only showing half of the Tempest Screen

morbidboy

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Set it up for a party with credits. After the party, I turned it off to reset and turned it back on. Now it's only showing half of the screen. Since I'm not too familiar with Vector monitors, I need some advice on how to fix it. Hoping that it'll be a quick fix.
 

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Taking a closer look D800 Red LED (on the main Monitor board) lights up for a second when powered on but then goes out. Anyone want to help out?
 
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looks like the capacitor on the neckboard was burned to shit at the bottom. Label reads 250V 33uF . Will I be able to do down to a local radio shack for this part or do I have to special order it. I've done cap kits but never bought a only one cap.
 

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looks like the capacitor on the neckboard was burned to shit at the bottom. Label reads 250V 33uF . Will I be able to do down to a local radio shack for this part or do I have to special order it. I've done cap kits but never bought a only one cap.

Go to your local store. All of them are different went it comes to parts from what I have seen. My town has two Radioshacks. One has a tiny parts bin and then other has 3 parts bin with tons of componets.
 
Re: the capacitor.

If you can find the right rating and type, go for it. The voltage rating needs to be Equal or GREATER. Never less.

The MFd rating needs to be the same. Not greater, not less, unless you understand exactly what circuit it is in, and can work the various equations to figure out where you are at, and where you will end up. (In other words, match the freaking MFd).

Changing the MFd rating in an LRC circuit can throw the entire circuit into disarray, and it won't work. It messes up the impedance.
 
The cap is likely a red herring. You need to check the frame-mounted transistors and the wiring from the deflection board to them.

Common problems with this stuff in no particular order:
- Transistors shorted to the monitor frame. Check continuity between the metal monitor frame and the casing of the bottlecap transistors. There should be no continuity. If there is, make sure the insulator that goes between those parts is okay and the screws aren't touching the edges of the hole through the frame.
- Broken wires on the transistor mounts. This happens all the time and is easy to miss with all the wiring in there. Just resolder any that have broken off.
- Bad solder joints on the deflection PCB headers that these transistors hook up to. Just pull the deflection PCB and reflow these.
 
Another thing that I have seen is when someone replaces a resistor at the beginning of the deflection circuit (for either horizontal or vertical) and puts the wrong value in. If it's too low, it shunts the deflection signal right to ground and you get no deflection in that quadrant...
 
Look at the WG6100 Quadrascan Monitor Manual Figure 15. The case transitors are shown in the drawing. Q706, Q705, Q102, Q103, Q606 and Q605. Using a meter on tone mode touch one lead to trasistor cap or mounting screw and the other lead to frame of the monitor, if the cap is not mounted correctly you will get a tone. Reposition the cap and check your screws, you should not get any tone when they are mounted correctly.

Another option would be to check for cold solderer points at the transitors on the main deflection board, P314, look for Q704, Q703, Q604 and Q603. They are attatched to heat sinks. Slightly touch each heat sink to see if there is any movement of the transitor legs, loose or cold solder joints will cause your screen to collaps either horizontally or vertically. See Figure 16 in the monitor manual for the transitor locations.
 
So it looks like it wasn't that cap. I replaced it but there was no change. I'll end up taking the monitor apart. I just don't have the time to do it.
 
I am betting q706. Pull the red connector off the deflection board and test the transistor using the diode test setting of your multimeter. (You can leave the tranny installed). If it tests good, test the other tranny behind it. These are the 2 transistors that are on the side of the monitor frame. The red connector is the one closest to the side of the monitor frame. If you leave it hooked up it will not test properly. Do this with the power off.

I really need to make some instructional videos.
 
I am betting q706. Pull the red connector off the deflection board and test the transistor using the diode test setting of your multimeter. (You can leave the tranny installed). If it tests good, test the other tranny behind it. These are the 2 transistors that are on the side of the monitor frame. The red connector is the one closest to the side of the monitor frame. If you leave it hooked up it will not test properly. Do this with the power off.

I really need to make some instructional videos.

My Star Wars has a WG6100 and has had the exact same problem, and it was just the connection to one of these transistors. One of the solder joints had gone bad, and would flake out after a few minutes. We were able to figure it out by gently wiggling the wire to the transistor while the machine was working, and it brought back the complete picture (for a moment). Once resoldered it has worked properly since, an easy fix. I don't know if this is what you have wrong, but it could be worth a try. If you try this, just be careful reaching in there, or use something non-conductive to wiggle the wires.

http://forums.arcade-museum.com/showthread.php?t=198446&page=2
 
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