Asteroids WG 19V2000 monitor going blank in center of screen

danpiraino1971

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Asteroids WG 19V2000 monitor going blank in center of screen

I have this weird issue that comes and goes during game play. The screen will go blank from the center down to the bottom of screen then comes back again. I would say on the left side of the lower right quadrant. It doesn't just blank out either it looks like it's scrolling from left to right. I put in another working Asteroids board to check if it was the game board, but it does the same thing which points me to the monitor. It's just strange. I never encountered this before.
 
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Start with the easy/simple things. Have you reflowed the solder joints on all of the connector headers on the deflection board? That should be done on all vector monitor boards, if it hasn't been done already.

Also, post a video to youtube if you can, as it will give more info.
 
Preventive Maintenance is #1 for 30year+ boards.
For monitors, this includes resoldering the headers and checking the wires/pins etc.

>> "The screen will go blank from the center down to the bottom of screen then comes back again." >> this implies poor connection somewhere (and not a logic issue)
 
Preventive Maintenance is #1 for 30year+ boards.
For monitors, this includes resoldering the headers and checking the wires/pins etc.

>> "The screen will go blank from the center down to the bottom of screen then comes back again." >> this implies poor connection somewhere (and not a logic issue)

It's already been determined to not be a logic issue. It does it on two different logic boards as I stated above. I have rebuilt G05s before just haven't had this issue yet. Not new to rebuilding xy monitors.
 
Start with the easy/simple things. Have you reflowed the solder joints on all of the connector headers on the deflection board? That should be done on all vector monitor boards, if it hasn't been done already.

Also, post a video to youtube if you can, as it will give more info.

I'm not convinced it just a bad solder joint. Because of the way it scrolls off and on. For example. The "c 1979 Atari Inc" at the bottom of the screen. It will go blank one letter at a time from the c of Inc all the way until the A of Atari. Then when it comes back the letters reappear one at a time going the other direction from the A of Atari to the c of Inc. Seems to me if it was a bad connection it would just all blank in and out all at once and not gradually from left to right like it's doing. I can see if I can get a video of it uploaded.
 
It kinda sounds like maybe the spot killer is momentarily kicking on just long enough to blank a portion of the screen, and then shutting off again allowing the beam to draw the rest of the image. You might try removing the spot killer LED and see if anything changes. If so, it should point to an issue with the spot killer circuit.
 
It kinda sounds like maybe the spot killer is momentarily kicking on just long enough to blank a portion of the screen, and then shutting off again allowing the beam to draw the rest of the image. You might try removing the spot killer LED and see if anything changes. If so, it should point to an issue with the spot killer circuit.

I haven't looked yet but if the spot killer is coming on wouldn't the LED be lite for that moment?
 
I haven't looked yet but if the spot killer is coming on wouldn't the LED be lite for that moment?

You would think so but the LED is a diode and like any other semiconductor could fail outright of fail so it is behaving marginally. Also it may be coming on too fast or too dim to be seen.

If it's not solder joints then it's semis or caps (or resistors - what's left lol) in the spot killer or Z amplifier. Something may be getting saturated which manifests the error and then gets a rest which makes it work again. The text disappearing/reappearing happens because unlike a raster (full frame at a time) the letters are being drawn sequentially (along with the other objects) and the failure happens during that particular time. More or less text may correlate to a tiny bit more or less time drawing other objects.
 
I'm not convinced it just a bad solder joint. Because of the way it scrolls off and on. For example. The "c 1979 Atari Inc" at the bottom of the screen. It will go blank one letter at a time from the c of Inc all the way until the A of Atari. Then when it comes back the letters reappear one at a time going the other direction from the A of Atari to the c of Inc. Seems to me if it was a bad connection it would just all blank in and out all at once and not gradually from left to right like it's doing. I can see if I can get a video of it uploaded.


I'm walking you through a process. And that process starts with the easy stuff. There can be cracks that you can't see, and any crack or partial connection can cause bad voltages that can cause all sorts of issues. It's not a guaranteed fix, but it's the first step in narrowing things down.

Reflow the connector pins with fresh solder, if you have never done it on that board. Then post a video and we will take next steps.
 
I haven't looked yet but if the spot killer is coming on wouldn't the LED be lite for that moment?

If you think about how many times per second the beam draws the screen, and the spot killer (if in fact it's the problem) is only active long enough to blank the very tail end of each pass before it starts again, we're talking about the spot killer being active for only hundredths of a second at a time. So it's entirely possible that the LED wouldn't be receiving power for long enough for it to light up at all or to be visible if it did... and as douglasgb said if the LED itself has failed then it might not come on at all, ever.

I second what andrewb says: bad solder joints is such a common issue that a reflow is a good idea even if you don't think it's going to fix the problem. It takes a lot less time to reflow some headers than it does to start removing and testing transistors and diodes, and then you'll have eliminated that as a possibility before moving on to the more time consuming stuff.
 
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I checked the pcb over, like you all suggested, with a magnifying glass and found one bad solder joint on pin 1 of P700. Residual flux on pins of P600. I'm going to remove the old solder and reflow and I will post my findings after I test it.
 
time for a video ...

21-amazing-video-stats-rbm-5-638.jpg
 
Ok, that's an interesting one.

I'm not certain on the display issue, but you do have an issue in the sound circuit for the saucer bullets on the game board, as the saucer bullets' sound isn't right. (It's distorted and too low). It's either a bad or missing cap, a bad 555 timer chip, or a bad or missing 2N3906 transistor. Check the parts around M8/M9, and see if any are missing or broken.


Can you post another video showing you putting the game into test mode? I want to see the crosshatch.

I'm guessing it's an issue with your Z circuitry. Maybe a marginal transistor. Need more info though.

Also, post another video where you turn the brightness up higher, so you can see the lines being drawn between the objects. Then let play a game or let attract mode run for 15 seconds or so.
 
Ok, that's an interesting one.

I'm not certain on the display issue, but you do have an issue in the sound circuit for the saucer bullets on the game board, as the saucer bullets' sound isn't right. (It's distorted and too low). It's either a bad or missing cap, a bad 555 timer chip, or a bad or missing 2N3906 transistor. Check the parts around M8/M9, and see if any are missing or broken.


Can you post another video showing you putting the game into test mode? I want to see the crosshatch.

I'm guessing it's an issue with your Z circuitry. Maybe a marginal transistor. Need more info though.

Also, post another video where you turn the brightness up higher, so you can see the lines being drawn between the objects. Then let play a game or let attract mode run for 15 seconds or so.

Told you it was weird. Yeah I already know about the sound issue. I will take care of that just want to figure this out first. I will see if I can do some other videos later tonight.
 
So, the phenomenon (fading vectors predominantly in the center area) is only at the beginning of the game play and then stops as the game is played, ie, warmed up, time "on" dependent?
A test screen vid would definitely be useful.
 
So, the phenomenon (fading vectors predominantly in the center area) is only at the beginning of the game play and then stops as the game is played, ie, warmed up, time "on" dependent?
A test screen vid would definitely be useful.

No it's the opposite of what you said. As game is played and sound gets faster toward the end, the fading happens. When a new game starts everything comes back but there has been a few games where it started to fade out at the beginning slightly. When attract mode is on the high score screen fades out all except the very top left corner. Then it goes to push start flashing on screen very clearly. I will put up a video of that too and a test screen.
 
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