Star Wars Amp help!!

masco73

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I got this Star Wars machine a while ago and it played blind. It has very low plays and had an untouched amp monitor. Our local repair man Ian (retrohacker) brought it back from the dead. It still had the dead red in it, which was replaced with a new one. Also he replaced lots of little things that the High voltage took out when it went. He could tell you what else he replaced because I have no clue.
Anyway, the problem is after it warms up about half hour or so it start to flash blue spider vector lines on and off. The longer it is on, the more it does it and longer intervals. Ian is positive it is a short in the tube. He tested the tube and it comes up fine. He tried to clear it, but it still is happening. I think he is stumped at this point, so I thought I would try asking the pros to get some new ideas. I made a short you tube video of it. Here is the link:

http://www.youtube.com/watch?v=YptxT4irheM


Thanks
 
It looks more like the brightness/screen control go way out of wack... I'd try cleaning the pots, or maybe try replacing the flyback again (maybe the replacement was bad). Finding another screen/focus adjustment may be tough, but that could be the problem as well. Does anyone near you have another Amp that you could try swapping individual boards?

DogP
 
Never seen that before with my amp star wars. It looks possessed. Does it say "I am the bishop of battle, I have 13 levels to master....etc"? jk.
 
A 6100 wouldn't really help any... are you sure it's only blue that does that, or is blue just turned up the most, so it looks mostly blue (I can't tell from the video, the brightness looks mostly white).

After it starts doing that, try going into the test mode and go to a screen that only has one color. If it stops doing that on all colors except blue, then I'd inspect the blue circuit. If it does it on the other colors and doesn't necessarily look blue anymore, then I'd inspect the brightness/screen circuit, and maybe the tube. If it does it on all color screens and still looks blue, then look at the blue circuit again, and maybe suspect the tube.

If it is for sure blue, you can pull Q25, and that should completely disable any control of the blue gun from any part of the circuitry, and if you still get the blue problem, then it's most likely the tube. If the tube ends up being the problem, it could be an intermittent H-K short on the blue gun, which a rejuvenator won't be able to fix, but you may be able to clear it either by taking the tube out, setting it face down on something soft (towel, carpet, etc) and lightly but firmly tap the the neck with a rubber handled screwdriver. This could knock the short out of the blue gun area and fix the problem. You could also isolate the heater voltage, which should just involve cutting the trace on the HV board that connects pin 9 of the flyback to ground (HTR2 on the schematics).

DogP
 
That bright line leach out is the exact same behavior you'll experience if you turn up the brightness too high on the flyback. I realize you said the flyback was replaced but none the less trace the two wires coming out of the flyback (Heater and focus). You'll see where they attach to the focus and brightness adjusters. Pull the rubber boots back on the heater (and for that matter focus) wires and resolder if necessary. Both are infamous for breaking loose. Also get into the service mode and set your colors. I strongly doubt you're having any gun issues - you're colors probably need to be fine tuned. Every Amplifone or WG monitor I've had have had incorrect voltages set as well as the colors needed fine tuned. Did Ian set this new flyback with a HV probe? These aren't a drop in and go replacement.

If they look ok then I would personally focus on the HV board. You need to measure the voltage output when the issue starts and narrow it down from there.
 
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I am no expert by any means but looking at your video you can clearly see the problem is only with the blue. The red and green text remain on the screen the correct size and color but the blue increases in size and has trace lines which you normally see when the brightness is turned up to high but the blue is only increasing in size or blooming. Not sure what that means but I have seen trace lines when their was a short in the tube and they can be rejuvenated with a tube tester. It could also be as simple as a loose connection, cold solder joint or bad pot, isn't their 2 pots for each color to adjust the gain. You might try the old tap and wiggle method wile the game is on wile watching the screen to see if it causes the condition to come and go. Just don't touch anything to get a shock. Just take something plastic or wood and tap each component on the deflection board. You never know you might find something simple to fix.
 
Yup, I've already done the old "tap and wiggle" on all the pots and transistors in the blue circuit, and I've checked and reflowed the solder joints. When the problem appears, it's very clearly only the blue going bright , none of the other colors are affected. I've also tried tapping on the neck of the tube.

I did use a picture tube tester, and left it on the tube for a good 45 minutes to an hour. This problem generally appears after half an hour, and it'll flicker on and off, then go solid. The tube tester showed no leakage anywhere. After reattaching the tube to the monitor and running the game, the problem reappeared after half an hour or so, which would lead me to believe that it's not the tube (it was already "warm" from the tube tester)

Reading over the schematic, I see two potential gotchas, both of which are "those damn brown jumpers". I replaced the jumpers on the HV board, but not the deflection board. There's one in the spot killer circuit, and there's one that feeds the video B+ to the drive transistors. Worth a shot, anyway.

-Ian
 
Starting to appear like it's a component over heating. Have you used any freeze spray on the board? If not I would try giving a shot to each component one at a time.If it is a heat problem then it might pop back on when cooled down sense it works when it's first fired up cold.
 
Reading over the schematic, I see two potential gotchas, both of which are "those damn brown jumpers". I replaced the jumpers on the HV board, but not the deflection board. There's one in the spot killer circuit, and there's one that feeds the video B+ to the drive transistors. Worth a shot, anyway.

I don't think the B+ or spot killer would have anything to do with a specific color though. Like I said in my other post, check Q25... maybe either swap it with one of the others (and see if the other color starts doing it), or just pull it all together. And check if the problem happens if you're on a screen with no blue (does the problem only happen when it's trying to draw blue?). You could also try a hair dryer to heat it up faster and see if the problem comes back faster than 30 mins. And if you turn it off and back on, I assume it keeps doing it (you don't have to wait 30 mins again, right)?

Swapping all those jumpers is definitely worthwhile though.

DogP
 
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