Asteroids Deluxe 19v2000

KidVidiot

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Is there a quick test to be able to tell if my problem is with the pcb or monitor?



The game always starts out fine, then after a few minutes almost all of the graphics fade away, leaving only a random ufo or shot flying across the screen near the bottom. The spot killer comes on and usually all screen activity goes away.



None of the fuses are blown. Monitor will come back to life after being powered down for a while.
 
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Is there a quick test to be able to tell if my problem is with the pcb or monitor?

The game always starts out fine, then after a few minutes almost all of the graphics fade away, leaving only a random ufo or shot flying across the screen near the bottom. The spot killer comes on and usually all screen activity goes away.

None of the fuses are blown. Monitor will come back down life after being powered down for a while.

Turn the brightness up and see what you see. Smells like monitor caps to me.
 
Turn the brightness up and see what you see. Smells like monitor caps to me.

Turned it on today, came up as normal, waited 20 minutes, graphics disappeared and spot killer came on. I turned up the brightness and the game graphics appeared with all the extra lines and the spot in the middle of the screen.
 
I'd start by working on the chassis, new caps and reflow everything. Also check / repin your molex and edge connector if anything looks rough

Still a chance it's the PCB, but much less likely than the monitor, I think.
 
As best I can remember, the G05-802 in my Asteroids was doing something similar- screen came up and could somewhat make out the vectors. Messing with the brightness and contrast helped a bit but only in a limited portion of pot travel ad was never quite perfect. I re-capped and it was fine afterwards. You might get away with just changing out the 1uF pp caps to the electrolytic ones the kits come with.
 
Your z voltage is falling for some reason. I'd suspect the pot or any caps in the vicinity. My bet is on the board if you see the objects when you crank up the screen. Measure the z output voltage (i think DC) before and after the fade.
 
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Your z voltage is falling for some reason. I'd suspect the pot or any caps in the vicinity. My bet is on the board if you see the objects when you crank up the screen. Measure the z output voltage (i think DC) before and after the fade.

So when it's first turned on and normal I measured the Z out on the pcb and for dc it stays mostly at .965 but drops to .78, .86 and back up. For ac it stays mostly at .65 and will drop down to .55

I waited for the screen to go out and after an hour or so I saw it all starting to go dim, then another 5-10 minutes later it was too dim to see at all. The spot killer was on. Tested the Z out voltages again (both when it was starting to go dim and when it was all gone) and they were basically the same as when there was no problem. The dc voltage started going up to 1.0, 1.1, but mainly stayed at .965.
 
recapped the monitor, reflowed p600 & 700, changed one of the four transistors...put it back in and now the top half of the screen is collapsed. wonderful. I was 99% certain recapping would make things worse.
 
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recapped the monitor, changed one of the four transistors...put it back in and now the top half of the screen is collapsed. wonderful. I was 99% certain recapping would make things worse.

Likely something went wrong when you changed the bottlecap. Why'd you swap it out? It didn't sound like you had any deflection issues.

Double-check your work there, check your header pins for cold solder joints, and make sure none of the wires to the deflection amps are broken. The ends that solder to the transistor mounts can get brittle over the years and break loose.
 
Likely something went wrong when you changed the bottlecap. Why'd you swap it out? It didn't sound like you had any deflection issues.

Double-check your work there, check your header pins for cold solder joints, and make sure none of the wires to the deflection amps are broken. The ends that solder to the transistor mounts can get brittle over the years and break loose.

they came in the cap kit so I figured why not. Then I started on the first one and it wouldn't line up at all like the original so I said fuck it. Accidentally unsoldered one of the wires to the transistor but soldered it back on afterwords. I guess something went wrong there? I had already reflowed the headers.
 
If the transistor didn't line up with the seat/screw holes you may have put it in upside down. They generally only go on one way, but can be forced in incorrectly, similar to what Bob writes about the G07 here (3rd pic from the top): http://therealbobroberts.net/g07repair.html

Yep, I'm guessing the pins are touching the chassis. The old transistors were all text facing down, but the new one would only line up the screw holes with text facing up. I ended up just throwing the old one back in, but I probably reinstalled it with the pins touching the chassis.
 
The text direction may not matter, especially if they are from different manufacturers. If you put it in upside, you could have shorted it to the frame, but you also switched the position of the base and emitter and may have taken something out on the deflection board as well. If you have a DMM, I would compare the old one (or whichever one you're going to put in) to either a new part or a working old part using the diode check function to make sure it's still good. Otherwise you'll introduce more issues when trying to troubleshoot.
 
Yep, I'm guessing the pins are touching the chassis. The old transistors were all text facing down, but the new one would only line up the screw holes with text facing up. I ended up just throwing the old one back in, but I probably reinstalled it with the pins touching the chassis.


Text direction doesn't matter. Did you power the monitor up with the new transistor in backwards?
 
Text direction doesn't matter. Did you power the monitor up with the new transistor in backwards?


Since I apparently don't know which way backwards is, I don't know. I powered it up with the new transistor the only way I could get it to fit naturally (text flipped from the old ones) and got the top half collapse, then I put the old one back in and still the same thing.
 
Really don't know what I'm doing wrong here. I turn to diode test and on two of the transistors I get a reading (from case to frame) that climbs from .100 to .980 and on the other two transistors I get no reading. Continuity (or lack thereof) seems to check out for all of them.
 
Yep, the collapse isn't a cap thing. Check for broken solder joints where the wires join the sockets. Make sure the contacts are springy against the bottlecap transistor legs when you change em. Make sure you reflow/replace the .156 headers that the harness connects to on the PCB.
 
You can install them backwards, but it should be obvious which way 'looks' correct if you compare the alignment of the legs vs the socket.
 
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