Battlezone display not adjust correctly

morphis72

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I have an Electrahome B&W vector in my Battlezone. About a year ago I finished repairing the montor and everything was groovy until a couple of weeks ago when the image seemed to shift and became disjointed.

When I put it on the test screen I tried to adjust the XSize, Ysize, Xbip, and Ybip controls on the game board but I just can't seem to get it to adjust and line up correctly. The image is stable but the words are at an angle and the lines are just not lining up.

I also noticed that if I use the size controls to shrink the image down so it only fills about half the screen there is no noise coming from the display but if I open up the image to fill the screen the display starts to make a buzzing noise or maybe that's chatter?

Anyone have any idea what I need to check?

I was trying to remember how to check the B+ on this thing but cant seem to find the info in the vector repair FAQ I downloaded. I know I had this set previously....
 
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Sounds like a game PCB problem - maybe one of the LF13201s at B11 or E11.

Dang, wish I had a known good board to swap it with. Anything I can do to verify this theory? I bought my battlezone PCB from MrBill08 and it he gave it a pretty solid going over before shipping it to me. Even a 'bullet proofed' board isn't fail proof. But, I would hate to start digging into it if nothing was wrong with it.
 
LOL - beat me to it. :burnout:

(Best way to confirm logic board or monitor issue is to use a scope and validate the XOUT and YOUT signals)

I do have a scope but haven't learned how to use it yet beyond just playing around with it a bit to look at wave forms. I will pull the PDF for the display and see if I can get anywhere with that.
 
Ok, super. Each of the four inner red knobs are for fine tuning, and should normally be in their locked position which seems to be fully clockwise. The outer, black knobs are what you'll set.

Both of the ones on the left should be set to 5v for Atari vectors. A higher volts per division will result in a smaller picture, and vice-versa.

The black knob in the upper right should be set all the way clockwise to X-Y, and the line leading down to the final knob implies it should be set for Y2 triggering - I'd leave it where it is for Y2 positive.

Hook the Y1 probe to the X output test point on the Battlezone board, and the Y2 to he Y output. Turn on the scope and adjust the two position knobs so the dot is in the middle of the scope. Then turn on Battlezone.
 
Ok, super. Each of the four inner red knobs are for fine tuning, and should normally be in their locked position which seems to be fully clockwise. The outer, black knobs are what you'll set.

Both of the ones on the left should be set to 5v for Atari vectors. A higher volts per division will result in a smaller picture, and vice-versa.

The black knob in the upper right should be set all the way clockwise to X-Y, and the line leading down to the final knob implies it should be set for Y2 triggering - I'd leave it where it is for Y2 positive.

Hook the Y1 probe to the X output test point on the Battlezone board, and the Y2 to he Y output. Turn on the scope and adjust the two position knobs so the dot is in the middle of the scope. Then turn on Battlezone.

I only have the one probe so maybe that is my issue? But, everything else is set as you described. not getting a form but am getting a picture so I know I have something set wrong. *edit* I just noticed the top left knob was not set to 5v. I fixed that but nothing really changed. *edit-2* I have tried both X and Y hookups on the board with no change as well as Y2 on the scope. Only change there is the direction the line is pointing on the scope. Still no form.
 

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I only have the one probe so maybe that is my issue? But, everything else is set as you described. not getting a form but am getting a picture so I know I have something set wrong. *edit* I just noticed the top left knob was not set to 5v. I fixed that but nothing really changed. *edit-2* I have tried both X and Y hookups on the board with no change as well as Y2 on the scope. Only change there is the direction the line is pointing on the scope. Still no form.

None of your knobs are set to use the scope in XY mode, but even if they were if won't help until you have two probes.
 
With only one probe, it would be useful to keep the scope in X-T mode and look on both Xout and Yout for trapezoid waveforms.

It is also best to do this in TEST MODE when the board is trying to draw the crosshatch pattern.

When using 10x probes, notice the voltage settings and time-base settings in the picture below.

Though these examples are from different vector games, the concepts/results are similar.

DSCN2653.jpg




The scope is not as useful if the OP doesn't have TWO probes. I suggest ponying up the $$ for a couple of cheap / new ones as andrewb suggested. Good investment too.
 
None of your knobs are set to use the scope in XY mode, but even if they were if won't help until you have two probes.

When I took the pic the top left knob was set wrong but I corrected that. The top right and one under that are set to xy and y2 + ... I think the flash on my phone makes it hard to see because it added a reflection that looks like white position marks on the left side of the position knob.

I will see what I can do about coming up with a second probe and try again.
 
None of your knobs are set to use the scope in XY mode, but even if they were if won't help until you have two probes.

Okay try two with the two knobs on the left set to 5v and the top right set to XY while the one under that is on Y+

I get a small square for my image. The lights in my basement are still casting a reflection on the black knobs but the white hash painted on the knobs is where I indicated above.
 

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Okay try two with the two knobs on the left set to 5v and the top right set to XY while the one under that is on Y+

I get a small square for my image. The lights in my basement are still casting a reflection on the black knobs but the white hash painted on the knobs is where I indicated above.

Awesome! Try switching from 5v to 2v on the left pair of knobs.
 
I moved the knobs around quite a bit and got this. I had to take the top right knob off of XY to get it though so it might be wrong?

https://www.youtube.com/watch?v=iaLn2eQOT-E&feature=youtu.be

Those are the raw waveforms for X and Y, and when not in XY mode you are plotting their amplitude versus time. Go back to the settings that gave you the small square, and change only the two knobs on the left to a smaller volts per division (a few stops clockwise) and that should make your small square into a bigger square.

Viewing the raw waveforms can tell you if the board is putting out appropriate signals (and yours are in the ballpark), but for the issue you describe it would be difficult to use them to verify the board is generating a perfect image. The goal here is to use the scope as a known-good vector monitor, and see if the issue persists (e.g., is a game board issue) or if the image is fine (e.g., is an issue with your monitor).
 
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