5200 behaves as if fire button "stuck"

[Big_Mo]

Wonder if anyone has an idea what could be causing this...

 

I just got a 5200 and noticed that something weird was happening. Some games played fine, but on others the control was screwy. When I put in Qix I discovered that the system was acting like the upper fire button was being held down. I switched four different controllers and this still happened. I then plugged in Dreadnought Factor and the game was continuously launching bombs, again as if the upper fire button was being held down.

 

Again, it's not the controllers. I've verified that.

 

I'd appreciate any thoughts on what could be causing this.

[atariksi]

Wonder if anyone has an idea what could be causing this...

 

I just got a 5200 and noticed that something weird was happening. Some games played fine, but on others the control was screwy. When I put in Qix I discovered that the system was acting like the upper fire button was being held down. I switched four different controllers and this still happened. I then plugged in Dreadnought Factor and the game was continuously launching bombs, again as if the upper fire button was being held down.

 

Again, it's not the controllers. I've verified that.

 

I'd appreciate any thoughts on what could be causing this.

 

Sounds like trigger line got latched on the GTIA chip (which supports that feature). Did you try to cold start the machine and see if it reset? I have had that happen because some cartridge switching caused it on warm cartridge exchange.

[Big_Mo]

Wonder if anyone has an idea what could be causing this...

 

I just got a 5200 and noticed that something weird was happening. Some games played fine, but on others the control was screwy. When I put in Qix I discovered that the system was acting like the upper fire button was being held down. I switched four different controllers and this still happened. I then plugged in Dreadnought Factor and the game was continuously launching bombs, again as if the upper fire button was being held down.

 

Again, it's not the controllers. I've verified that.

 

I'd appreciate any thoughts on what could be causing this.

 

Sounds like trigger line got latched on the GTIA chip (which supports that feature). Did you try to cold start the machine and see if it reset? I have had that happen because some cartridge switching caused it on warm cartridge exchange.

I checked this and the state of "coldness" of the system isn't at fault. However, I noticed that the behavior isn't entirely consistent. I notice it mostly on games on an old Multicart, and I only have a dozen or so 5200 carts at hand. But it's not consistent on all games on the multicart. For instance, Countermeasure behaves fine on both the Atari cart and the multicart, but then Kangaroo is unplayable because when the game starts the mama Kanga just punches repeatedly, and ergo can't be moved.

[bohoki]

have you started a game then pull the plug and see if it is still shooting?

 

are any of your pins bent?

[Big_Mo]

have you started a game then pull the plug and see if it is still shooting?

 

are any of your pins bent?

I have. That's not the issue. It happens on both controller ports as well.

[atariksi]

have you started a game then pull the plug and see if it is still shooting?

 

are any of your pins bent?

I have. That's not the issue. It happens on both controller ports as well.

 

Try swapping GTIA chips with a known working one.

[Big_Mo]

have you started a game then pull the plug and see if it is still shooting?

 

are any of your pins bent?

I have. That's not the issue. It happens on both controller ports as well.

 

Try swapping GTIA chips with a known working one.

That's what I was going to try next. Thanks!

[Big_Mo]

Ok. I pulled open the 5200 and discovered two things:

 

1. The Antic chip that's in there has pin 11 (A2) bent so it doesn't go into the socket.

 

2. If I put a different Antic chip in (with no bent pin) the graphics mode gets messed up, but the stick fire button problem persists.

 

Could the 5200 diagnostic cart help diagnose the problem?

Edited October 10, 2010 by Big_Mo

[atariksi]

Ok. I pulled open the 5200 and discovered two things:

 

1. The Antic chip that's in there has pin 11 (A2) bent so it doesn't go into the socket.

 

2. If I put a different Antic chip in (with no bent pin) the graphics mode gets messed up, but the stick fire button problem persists.

 

Could the 5200 diagnostic cart help diagnose the problem?

 

You sure you got the right pinouts. A2 would be needed by ANTIC. I would say pin 4 (light pen) may have effect on trigger on GTIA. Try pulling that up to see if it's ANTIC related.

 

I see some ANTIC pinouts here:

 

http://www.xmission.com/~trevin/atari/antic_pinout.html

[Big_Mo]

Ok. I pulled open the 5200 and discovered two things:

 

1. The Antic chip that's in there has pin 11 (A2) bent so it doesn't go into the socket.

 

2. If I put a different Antic chip in (with no bent pin) the graphics mode gets messed up, but the stick fire button problem persists.

 

Could the 5200 diagnostic cart help diagnose the problem?

 

You sure you got the right pinouts. A2 would be needed by ANTIC. I would say pin 4 (light pen) may have effect on trigger on GTIA. Try pulling that up to see if it's ANTIC related.

 

I see some ANTIC pinouts here:

 

http://www.xmission.com/~trevin/atari/antic_pinout.html

 

Whoops! I got my eye on the wrong chip! Disregard that.

 

I swapped ANTIC and no difference. I also bent pin4 up to see if that would do anything, but still, nada.

Edited October 12, 2010 by Big_Mo

[atariksi]

Ok. I pulled open the 5200 and discovered two things:

 

1. The Antic chip that's in there has pin 11 (A2) bent so it doesn't go into the socket.

 

2. If I put a different Antic chip in (with no bent pin) the graphics mode gets messed up, but the stick fire button problem persists.

 

Could the 5200 diagnostic cart help diagnose the problem?

 

You sure you got the right pinouts. A2 would be needed by ANTIC. I would say pin 4 (light pen) may have effect on trigger on GTIA. Try pulling that up to see if it's ANTIC related.

 

I see some ANTIC pinouts here:

 

http://www.xmission.com/~trevin/atari/antic_pinout.html

 

Whoops! I got my eye on the wrong chip! Disregard that.

 

I swapped ANTIC and no difference. I also bent pin4 up to see if that would do anything, but still, nada.

 

Of the two chips, ANTIC would be much less likely to cause trigger problems than GTIA.

[Big_Mo]

Ok. I pulled open the 5200 and discovered two things:

 

1. The Antic chip that's in there has pin 11 (A2) bent so it doesn't go into the socket.

 

2. If I put a different Antic chip in (with no bent pin) the graphics mode gets messed up, but the stick fire button problem persists.

 

Could the 5200 diagnostic cart help diagnose the problem?

 

You sure you got the right pinouts. A2 would be needed by ANTIC. I would say pin 4 (light pen) may have effect on trigger on GTIA. Try pulling that up to see if it's ANTIC related.

 

I see some ANTIC pinouts here:

 

http://www.xmission.com/~trevin/atari/antic_pinout.html

 

Whoops! I got my eye on the wrong chip! Disregard that.

 

I swapped ANTIC and no difference. I also bent pin4 up to see if that would do anything, but still, nada.

 

Of the two chips, ANTIC would be much less likely to cause trigger problems than GTIA.

I was clearly not thinking clearly wen I said it was Pin 11 of ANTIC that was bent up...it was pin 11 of GTIA. It's when I swapped that part with one with the 11 pin bent down that the screen got corrupted.

 

Any idea why they'd bend Pin 11 up?

[Big_Mo]

I did a cart by cart check and realized that the "stuck" button only occurred with my old 5200 multicart, and not with any individual game carts, so it appears the multicart is at fault, not the 5200 hardware (I was thrown initially because some other carts were malfunctioning, but that turned out to be some dirty contacts).

 

I took the multicart apart to check it and while it's possible there's been some bit-rot on one or more of the EPROMs, I did notice that one of the contacts on the cart's edge connector appears to be worn away. If "top" is where I think it is, it's Pin1/D0 (it's the leftmost pin on the side of the cart towards the back of the machine). Could that have anything to do with this?

[atariksi]

Ok. I pulled open the 5200 and discovered two things:

 

1. The Antic chip that's in there has pin 11 (A2) bent so it doesn't go into the socket.

 

2. If I put a different Antic chip in (with no bent pin) the graphics mode gets messed up, but the stick fire button problem persists.

 

Could the 5200 diagnostic cart help diagnose the problem?

 

You sure you got the right pinouts. A2 would be needed by ANTIC. I would say pin 4 (light pen) may have effect on trigger on GTIA. Try pulling that up to see if it's ANTIC related.

 

I see some ANTIC pinouts here:

 

http://www.xmission.com/~trevin/atari/antic_pinout.html

 

Whoops! I got my eye on the wrong chip! Disregard that.

 

I swapped ANTIC and no difference. I also bent pin4 up to see if that would do anything, but still, nada.

 

Of the two chips, ANTIC would be much less likely to cause trigger problems than GTIA.

I was clearly not thinking clearly wen I said it was Pin 11 of ANTIC that was bent up...it was pin 11 of GTIA. It's when I swapped that part with one with the 11 pin bent down that the screen got corrupted.

 

Any idea why they'd bend Pin 11 up?

 

Delayed response but just checked the GTIA pinouts:

Trigger lines are Pins 8..11 on the GTIA chip with Pin 8 labeled as T0 and Pin 11 as T3. T3 (pin 11) would only be the 4th joystick port.