Space Duel troubleshoot

Kalamath

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Since I got Asteroids up and running today, I figured it was time to start on my Space Duel. I bought the game DOA. Inside it is very clean. The monitor is a WG 19K6101, again, insides are very clean.

Turning on power lights all cab lighting, and provides good voltages all over: PCB, ARII, Monitor. In fact, it's closer to "proper" voltages than any Atari game I have. Game is totally dead though.
-Spot killer on
-Solid lights on CP (game is set to free play)
-Self Test switch & all buttons have no effects
-Game does NOT play blind. No output from XY on my scope.
-Swapped in a working 6502 CPU, same conditions as above.

Pin40 on the AVG is pulsing like mad. Jumpering WDDIS to GND has no effect. Pin40 on the CPU is LOW.

I'm really not sure how to proceed on this one. I've got my multi meter, logic probe, and oscilloscope ready, Journey playing, and Robotron nearby in case I need a break. Any suggestions?
 
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Ok, on most games you just have to let it watch dog for a few seconds and then put the reset pin high. I usually use a 1k ohm resistor and the +5. Then you use the scope to look at the address lines and data lines and that should give you a clue as to what is mucked up.

Check the buffers at B1, C1, and F2 and see what is there on the scope. Don't forget to check the clock on the cpu pin 37
 
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Let it sit in test mode for about 30 seconds..see if you get low tones. There are a couple of Roms and Rams that will keep it from booting into test mode. See if its still watchdogging in test mode also. Pull the Pokeys, I had a space duel board that was stuck in watchdog, and it was one of the pokeys. I always suspect the buffers. and I dont think its ever been one. The AVG will also cause watchdogs if its not working. Do you have another color vector board you can swap AVGs with?
 
Thanks guys, gives me someplace to start. I'm just getting started with the scope, so I'm not sure how much I'll accomplish with that, but I'll do my best. It was awesome to be able to use it to verify my asteroids PCB was putting out vector information.

Only color vector I have aside from this is Tempest. Terrified to even look at that thing crosseyed, lol.

I'll get to it this afternoon and see what I can dig up...
 
In your initial post you said ...

first thing I did was check pin40 (watchdog) of the AVG with my logic probe. It's pulsing like mad.

That really threw me of the track for a little while since pin 40 of the AVG chip is an output, bit 2 of the output address, so it just didn't make any sense.

Then I realized that you meant pin 40 of the 6502 CPU which is the /reset input.

Since the AVG chip is a known high rate of failure item, I suggest replacing it or borrowing a known-good one to use to test your board. If it happens to be the AVG causing your trouble, it could save you a lot of trouble and time.

The majority of Atari game owners who have any of the six AVG-chip supported games usually keep a spare AVG chip or logic replacement around for exactly the situation in which you are finding yourself.

Bill Boucher
http://www.biltronix.com/BXAVG.html
 
Pulsing implies your crystal and at least some clocks are good. If self-test won't run I'd start by cleaning and verifying the ROMs an making sure they are in the right sockets! If still no go, swap the 6502A CPU for a known working one (1.5 MHz). BTW, pin 40 of the CPU is the RESET line. Pin 40 of the AVG is the output AVG2 so mad pulsing on that pin is good!

Edit: cross posts. Also, Bill was too modest to overtly state that he sells an AVG replacement, but as a satisfied customer I will!
 
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Thanks guys! Yesterday turned out crazy for us, and I didn't get any arcade time in. Bill, you are absolutely right on the chip, of course...I simply misstated what I was checking. I was reading through the schematics and that was something they suggested to check right away....reset on the CPU is pulsing.

I'd already poked around and found Bills AVG solution, and am putting in an order right after I hit "click" here...
 
Still waiting to hear back from Bill for the BXAVG. In the meantime I pulled the monitor and plugged it up to my Tempest. She works! So that's a plus!

So, my "typo" the other day wasn't a typo after all. I rechecked, and the reset line (pin40) on the CPU chip is NOT pulsing...it's steady low. I also swapped in the chip from my Tempest...same deal, and same conditions: spot killer on, no blind game, no test mode, etc.

I recall another thread about pulling a pin somewhere to bypass XY to see if the game will play blind...going in search of that now.
 
...reset line (pin40) on the CPU chip is NOT pulsing...it's steady low. I also swapped in the chip from my Tempest...same deal, and same conditions: spot killer on, no blind game, no test mode, etc.

If you mean the AVG chip, if it's still out you could put the SD AVG into the Tempest and make sure the Tempest still runs. If so you'll know both AVG chips are good.

I recall another thread about pulling a pin somewhere to bypass XY to see if the game will play blind...going in search of that now.

I know you can do that with Asteroids and probably with SD too. Might be pin 6 of the AVG, honestly I've never tried.

Is it possible you are getting test mode but the volume is turned down or speaker disconnected?
 
No, I meant the CPU, the 6502. If pin40 was pulsing, I'd know it was watchdogging, but it's not. It's steady low.

I didn't try swapping the AVGs because I wasn't sure they were interchangable between SD and Tempest. Are they? In any case, Bill has one on the way for me. I figured it would be prudent to have one on hand regardless.

Definitely no test mode...volume pot works fine, going off the level of hum.
 
So...if I'm not watchdogging, and voltages are ok (checked yet again), but I'm not getting test mode....something very elemental to the system isn't functioning.

CPU works, just double checked again in Tempest.
Electrolytic caps are ruled out, tested all on the ESR.

I must have bad ICs, or other components (diodes, resistors, etc). Is my logic sound here? I'm studying the schematics but I don't know enough to narrow this down to the chips that are needed for the self tests to run.
 
If its not watchdogging in test mode, then Id assume its running. Pull the Pokeys out and try again. I had a similar problem, watchdog in run mode, no screen in test mode (although it made a low tone in test mode after a while), and it ended up one of the pokeys was causing the watchdog.
 
Pulled the pokeys out, same results. NO watchdogging in either run or test mode.

So spotkiller remains on, buttons lit but no response. I KNOW these conditions point to something, I just don't know what...man it's frustrating.
 
Next I'd either:
-increment the location of the RAM chips a la marching ants (ie, take out L7 and move J7 to L7, M7 to J7, K7 to M7, E1 to K7, H1 to E1 and put L7 in at E1)
-remove them all and try self-test
-replace them with known good RAM

and/or

-remove all the ROMs aside from R7 and N/P7 which I think are the ones where self-test code is contained

if you get self-test to run then one of the missing chips may be shorting a data line.

Did you include the +10.3v unreg at edge connector E in your voltage checks? It's used for the power on reset.
 
Ok tried all that. No change in startup status. Still no test mode. My 10.3v is a little low, 9.4v but guessing thats ok since it's unreg. (to clarify, I did all of that except swap ram...it's not socketed and I'll have to first order sockets etc...)

Something (or nothing, not sure)...I was rechecking voltages for the Nth time, and decided to check all the molex pins on the ARII.
P7
pin1 (+5v rtn) is nill
pin2 (-sense) is nill
pin3 (+sense) is +5v
pins 5 & 6 (+5v reg) are spot on +5v

Question: Is that a problem on pins 1 & 3? I don't exactly understand what the sense lines do yet (I'm reading up on that now) or if this could be the issue why it's not booting up.
 
Ok tried all that. No change in startup status. Still no test mode. My 10.3v is a little low, 9.4v but guessing thats ok since it's unreg. (to clarify, I did all of that except swap ram...it's not socketed and I'll have to first order sockets etc...)

Something (or nothing, not sure)...I was rechecking voltages for the Nth time, and decided to check all the molex pins on the ARII.
P7
pin1 (+5v rtn) is nill
pin2 (-sense) is nill
pin3 (+sense) is +5v
pins 5 & 6 (+5v reg) are spot on +5v

Question: Is that a problem on pins 1 & 3? I don't exactly understand what the sense lines do yet (I'm reading up on that now) or if this could be the issue why it's not booting up.


(+5V return) and (-sense) both are references to ground in this case so 0V with respect to ground is of course correct and required.

Just to clarify... Tempest does not have the AVG chip (Atari part# 137179-001). Tempest predates the 6 games that have the AVG chip.

Kalamath, just my 25 cents, I think that you should just wait until your new AVG replacement arrives and see if that fixes the game. With any luck, it will. Original AVG chips are notorious for their high failure rate. If your original AVG is bad right now then you are struggling to no avail. No disrespect to your troubleshooting skills intended here but the more stuff that you fiddle with (like removing various ICs), the more likely you are to accidentally create a new problem. Although it sounds like you have done a good job so far, I think you should wait and see what the BXAVG does (or doesn't) do for you before you even think about pulling ram or anything. It will get there soon, probably a week at most.

Bill Boucher
 
No offense taken Bill, in fact I'm pleased because I had come to the same conclusion yesterday when I shut things down for the night. I've done pretty much all I can for now, I think.

I also know a lot more about how this machine works than I did when I started, so it's time well spent. I also greatly appreciate the feedback everyone has lent.
 
BXAVG in the house. No change in situation. Power LED on the BX is lit, no activity (tried a diff. cpu in conjunction with the BX also). Spot killer remains, start/select on steady, test switch & controls make no effect.

So this is going come down to a lower level trouble shoot after all. Uuugh! I still don't know enough, but I'm going to do my best. It has to be something very fundamental if it's not even getting to test mode.
 
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