WG6100 - Spot Killer on

[DarrenF]

I have replaced all the tl082's with new ones because I read that sometimes they cause issues.

I have a scope and see a square wave going to the the CPU 37,39. Could you explain how to check if the reset line is staying high and how to verify if there is activity on the data and address lines?

Also I don't get a line, I only get a slightly moving spot.

Sorry, I didn't read the whole thread, thus didn't realize you have a scope...

OK, the square wave on on the 6502 pins 37 & 39 is your clock (and shifted clock). Good.

The reset line is pin 40 on the 6502. If it is periodically going low (0V) then the CPU is being reset by the watchdog circuit. It should briefly low at power-up, then stay high (5V) all the time.

By "verify activity" I mean check that it's not simply staying high or low, but is in fact going up and down (0V and 5V) as the CPU puts values on the data and address bus. Fiddle with your sweep speed to find a setting where you can see the clock pulses, this same setting should be good to see the other lines on the CPU. 6502 pinout is here: http://www.xmission.com/~trevin/atari/6502_pinout.html so you can find the data and address lines. I'd expect all of the data lines to have activity. Not all address lines may be used (depending on the game memory map), but I might expect all of the lower ones to be active (A0-A10 or 12).

If you're reset line isn't going low, and there's activity on the data/address lines, then we can be reasonably certain that the CPU is operating and executing code. Not just that: executing _correct_ code, because if the code is jacked, it won't be resetting the watchdog timer, and that'll in turn reset the CPU.

OK, if it's not moving on the Y-axis, then it may have issues too. Personally, if I didn't have a known-working monitor, I'd be using a scope in X-Y mode to check for output. Otherwise you can't be sure if you're getting no signal due to the PCB, the wiring, or the monitor. Hook a scope up to the X-OUT and Y-OUT test points (and a GND reference) and you've isolated the PCB.

 

[delayed]

I went ahead and swapped out the CPU for another one and it brought up the test screens. They are bad. I think the 8th ROM might be bad, but I am not sure. The beep test seems to change. Below are the test screens and a link to the beep sounds.

Feels like I am getting somewhere now. Image and sound.

http://www.youtube.com/watch?v=0MpokxFLkBE

 

[DarrenF]

Check out the manual here: http://arcarc.xmission.com/PDF_Arcade_Atari_Kee/Star_Wars/Star_Wars_TM-225_2nd_Printing.pdf

p24 has the beep code info.

That doesn't sound like any of them to me...

 

[delayed]

I thought it was strange also because it seems to be changing. I am going to redo the voltage readings tonight and see what changed. Perhaps that will point me into the correct direction.

Do you happen to know where I can buy the CPU and other chips for this? I would like to replace the one I took out of the other board.

 

[delayed]

I was able to fix much of the visual issue with messing around with the other 2 pots on the board. I could not fix any of the text issues.

I plugged in the working board and listened to the beep test and it sounds the same as the broken one. I also took out 6 different ROMs and restarted each time. I could tell no change in the beep test with a ROM out of socket.

I noticed within the test screen, when compared to the working board, that the broken board does not have the cross bars within the beep test screen.

When I take the game out of test mode into game mode I get a straight line. Does this mean that the X or Y output is stuck?

Below are the updated visuals.

 

[DarrenF]

I was able to fix much of the visual issue with messing around with the other 2 pots on the board. I could not fix any of the text issues.

I plugged in the working board and listened to the beep test and it sounds the same as the broken one. I also took out 6 different ROMs and restarted each time. I could tell no change in the beep test with a ROM out of socket.

I noticed within the test screen, when compared to the working board, that the broken board does not have the cross bars within the beep test screen.

When I take the game out of test mode into game mode I get a straight line. Does this mean that the X or Y output is stuck?

Below are the updated visuals.

Wow. Good work there. Much nicer looking. Were those the "BIP" pots on the PCB you adjusted??

I think you can guess that your monitor is at least "OK"... and it looks like your X & Y amps and outputs are "OK" as well, since it is able to draw a nice box and crosshatch etc. The problem with the text... I'm not really sure. Did I mention that I don't have a SW? or even a color vector? Closest I've got is a Battlezone, which also has the AVG, but is B&W. Anyhow, if I had to take a wild-ass guess, I'd look at the integrator or zeroing switch in the AVG.

Since you're getting output in test mode, but nothing in game mode, I might suspect the ROMs (or their sockets). Maybe scope the reset pin in game mode to see if it's resetting...

 

[delayed]

Yes, the BIP pots did the trick. This is a tempest not a Star Wars if that matters?
I guess I might need to start a new thread since the spot killer is no longer the issue.


Which is the reset pin? and the AVG?




"I'll look at the integrator or zeroing switch in the AVG.

Since you're getting output in test mode, but nothing in game mode, I might suspect the ROMs (or their sockets). Maybe scope the reset pin in game mode to see if it's resetting..."

 

[DarrenF]

This is a tempest not a Star Wars if that matters?
Which is the reset pin? and the AVG?

Oops. Not sure why I was thinking SW. Luckily, almost everything I wrote applys the same.

I was referring to the reset pin of the CPU, which is a 6502 in Tempest. It's in the upper-right corner of this pic: http://www.xmission.com/~trevin/atari/6502_pinout.html It's labeled "RST" with a line over it. The line overbar means "active low", or that it's "normally" high (5V) but gets pulled "low" (0V) to active it (reset the CPU). I'm kind of expecting that yours in getting reset (getting pulled low) periodically in game mode.

AVG = analog vector generator. It's not a single chip, but rather a whole sub-system. Atari used it on all but their earliest vector games (which used the DVG, digital vector generaor).