Asteroids Deluxe vectors breaking up

scottz29

Member

Donor 2024
Joined
Sep 1, 2006
Messages
732
Reaction score
21
Location
Macomb, Michigan
I have a very strange problem with my Asteroids Deluxe (upright). Towards the left edge of the screen, occasionally the vectors of certain objects will start to break apart/distort. Other times, objects can pass through that same area without a problem. Problem occurs only at the left edge of the screen.

V2000 monitor. Recapped. Reflowed headers. New big blue. Adjusted X & Y gain using test pattern. Test pattern perfectly adjusted with no distortion.

Problem goes away when X gain is reduced to the point where the screen is about half normal width.



Any suggestions are appreciated.
 
Interesting....

This is a great video. I always wondered what the 'distorted asteroids' looked like as it was hard to understand from other posts what was actually being seen. This captures it perfectly and is something I have never seen on any of the vectors I have worked on. Definitely not linearity as I was thinking before I actually saw it. Almost like the X/Y signal is just not strong enough. Maybe this is a PCB issue....or bad/flaky power transistor mounts?

Will be interesting to see what the Asteroids experts have to say....
 
Last edited:
Update...

Capped board. Result was as I expected -- bad caps were requiring the gain to be cranked up so high that distortion became apparent. After caps, I was pleased to see the test grid was super wide on both X and Y axis. Adjusted gain pots back down, and the problem has decreased, but is still apparent in certain sections of the upper left quadrant of the screen - it is the worst right in the corner.

Strange thing is the ship does not distort at all no matter where you fly in that area. Asteroids are the worst. Sometimes in that area (upper left region), an asteroid will just break apart into the jagged lines seen in the video, while other asteroids around it are fine.

Really would just like to know what is happening on the board that causes that distortion...
 
Update...
Realized I hadn't capped the HV board, which I did. Problem is now worse. It appears the entire left 1/4 of the screen is being crushed inwards.

This is most noticeable in the test grid and high-score entry screen where the left 1/4 of the screen is being smashed in and vibrating wildly. As the game is left on, the problem gradually goes away, but not completely.

There's also a slight slow pulsing wave that goes through the top left of the screen, noticeable by the player 1 score.

I'm thinking HV diode at this point? Ideas?
 
I had a very similar issue with my 15V2000 in my AD cabaret. Do you have an o'scope? If so, try it there. Might be the monitor power supply is drooping. Do you have the two big ceramic resistors (3.9 Ohm) on the chassis? Have they been bypassed with wires?
 
Unfortunately I don't have an o-scope. One ceramic resistor was wire-modded, one was not. Can't remember which, I can check when I get home. Could that be the culprit? What does that wire mod do?
 
Those resistors are there limit the inrush current when you turn on the power and try to charge those big fat caps. Could be 100's of amps for a very brief time. With the resistors, the current is limited to maybe 10-20 amps peak. But in steady state, the current drawn by the monitor causes a voltage drop across the resistors. IIRC, it was somewhere around 5-8 volts. With the wire shorting out the resistor, you don't have that problem.

Take another look and see which resistor is shorted. The one that isn't could be your problem. You can check it by shorting the resistor with a piece of bus wire to see if the problem goes away.

If this is your problem, I would replace the resistors and/or wire with a nice NTC thermistor. In fact, I did that in my 15V2000. It the "proper" solution. I think there was a service mod from the mfr to short those resistors. But a thermistor is a better solution. It's nicer to your caps in the long run.
 
Finally got a chance to do the wire mod last night.... no change!! :001_ssad: Game starts up with the left 1/4 of the screen smashed in -- anything going into this area, the vectors break apart into "squiggly" lines.

The problem goes away about 90% after about a half hour of warming up, but never completely disappears.

Suggestions?
 
I know it's basic but have you tried changing the pots? I've pulled my hair out chasing monitor problems before that were fixed by simply changing the pots, even things I swore were logic related.

Another shot- how about the DAC's? Socket those and then swap them to see if your problem changes axis (normally I'd suggest going with a scope, but you mentioned you didn't have one).

Going a little deeper, I wonder if something could be amiss with the 244's maybe? That might explain why the ship isn't corrupted but the rocks are.

Be sure to post a follow-up so we can all see what it was.
 
My AD does the exact same thing in the upper left corner just like yours. Supposedly the monitor was capped within the last few years, but I haven't started trouble shooting it yet. If I get to it soon and figure it out I'll certainly bump this thread. Of course if you resolve the issue before I do I would greatly appreciate it if you would bump this thread with what worked for you ;).
 
I am having the same problem with my Armor Attack. I worked on it last night for about an hour but didn't get anywhere. I'll update if i get mine fixed and will be watching your thread here. Good luck
 
I had the same problem as the OP. I shorted both large ceramic resistors (R100 and R101) with wire (not sure of the gauge) to test if they were the problem and it cleared up everything. I would really like to fix them "properly", so does anyone know the specs, or the part number for the NTC Thermistor that a previous poster mentioned?
 
I had the same problem as the OP. I shorted both large ceramic resistors (R100 and R101) with wire (not sure of the gauge) to test if they were the problem and it cleared up everything. I would really like to fix them "properly", so does anyone know the specs, or the part number for the NTC Thermistor that a previous poster mentioned?
I just grabbed the closest fit to what I wanted from the local brick-n-mortar. The ones I used are not marked in any way and it's been a long time. They measure between 4.5 and 5.0 Ohms "cold" and are 1/2" in diameter. You should be ok starting with 4 Ohms cold and rated at 2-3 Amps continuous. The monitor will warm up slower than one modded with wires, but mine only takes 15-30 seconds, IIRC.
 
Back
Top Bottom