Problem with joystick port in ATARI 400

[mariusz]

Something is wrong with joystick port in my Atari 400. It seems that in the connected joystick, fire works all the time. In some games, which do not use fire, this do not mind, but in the other, game becomes impossible (you jump all the time etc.). What can be broken? (joystick is definitely good, checked on another computer. Pins of joystick port in Atari are straight).

[mimo]

a bad connection to the motherboard or POKEY chip failure?

[sup8pdct]

Something is wrong with joystick port in my Atari 400. It seems that in the connected joystick, fire works all the time. In some games, which do not use fire, this do not mind, but in the other, game becomes impossible (you jump all the time etc.). What can be broken? (joystick is definitely good, checked on another computer. Pins of joystick port in Atari are straight).

 

Maybe a bad connection to the CPU board, a bit of crud somewhere where it shouldn't be or maybe the Ctia/Gtia needs to be reseated or replaced.

 

James

[mariusz]

Yup, GTIA was the problem.

[ianoid]

In a similar vein, I have a 400 that only gets fire out of ports 1 and 2. I reseated the GTIA and no dice (didn't replace it, would need to buy parts). Any suggestions as to whether there is a high yield part I can replace to get it working? I don't have oscilloscopes or the capacity to replace ports, but I doubt it's the port/s when both ports misbehave the same way.

[atariksi]

In a similar vein, I have a 400 that only gets fire out of ports 1 and 2. I reseated the GTIA and no dice (didn't replace it, would need to buy parts). Any suggestions as to whether there is a high yield part I can replace to get it working? I don't have oscilloscopes or the capacity to replace ports, but I doubt it's the port/s when both ports misbehave the same way.

 

Most likely GTIA chip. Are you testing in BASIC as I don't know many games that use 3rd and 4th trigger lines?

 

Maybe your are using an XL/XE OS in your Atari 400.

[ianoid]

In a similar vein, I have a 400 that only gets fire out of ports 1 and 2. I reseated the GTIA and no dice (didn't replace it, would need to buy parts). Any suggestions as to whether there is a high yield part I can replace to get it working? I don't have oscilloscopes or the capacity to replace ports, but I doubt it's the port/s when both ports misbehave the same way.

 

Most likely GTIA chip. Are you testing in BASIC as I don't know many games that use 3rd and 4th trigger lines?

 

Maybe your are using an XL/XE OS in your Atari 400.

Thanks for the reply.

 

Naw, just testing the joystick ports using Centipede. That's my favorite for Atari 8-bit joystick testing.

 

I don't actually know how to test the 3rd and 4th ports. I just test the 1st and 2nd ports, and both have the same issue- Fire only response from the joysticks (which again are fully tested and work).

 

GTIA again? B&C has them for $5. Should I go for it?

[sup8pdct]

As I understand it, you are not getting any left,right up or down movement. If that is the case, you will need to check the pia chip (6520) it is located towards the front on the mother board of the 400.

If you have asteroids cart, you can test all 4 joystick ports

 

James

 

 

 

In a similar vein, I have a 400 that only gets fire out of ports 1 and 2. I reseated the GTIA and no dice (didn't replace it, would need to buy parts). Any suggestions as to whether there is a high yield part I can replace to get it working? I don't have oscilloscopes or the capacity to replace ports, but I doubt it's the port/s when both ports misbehave the same way.

 

Most likely GTIA chip. Are you testing in BASIC as I don't know many games that use 3rd and 4th trigger lines?

 

Maybe your are using an XL/XE OS in your Atari 400.

Thanks for the reply.

 

Naw, just testing the joystick ports using Centipede. That's my favorite for Atari 8-bit joystick testing.

 

I don't actually know how to test the 3rd and 4th ports. I just test the 1st and 2nd ports, and both have the same issue- Fire only response from the joysticks (which again are fully tested and work).

 

GTIA again? B&C has them for $5. Should I go for it?

[ianoid]

I replaced the PIA chip (it says CO14795-12 R6250 on the chip) and now the joysticks work pefectly!

 

Thanks for the advice sup8pdct!

 

If this hadn't worked, I'd probably have trashed the system because I just don't have time to get this working otherwise. Yay!

 

 

As I understand it, you are not getting any left,right up or down movement. If that is the case, you will need to check the pia chip (6520) it is located towards the front on the mother board of the 400.

If you have asteroids cart, you can test all 4 joystick ports

 

James

 

 

 

In a similar vein, I have a 400 that only gets fire out of ports 1 and 2. I reseated the GTIA and no dice (didn't replace it, would need to buy parts). Any suggestions as to whether there is a high yield part I can replace to get it working? I don't have oscilloscopes or the capacity to replace ports, but I doubt it's the port/s when both ports misbehave the same way.

 

Most likely GTIA chip. Are you testing in BASIC as I don't know many games that use 3rd and 4th trigger lines?

 

Maybe your are using an XL/XE OS in your Atari 400.

Thanks for the reply.

 

Naw, just testing the joystick ports using Centipede. That's my favorite for Atari 8-bit joystick testing.

 

I don't actually know how to test the 3rd and 4th ports. I just test the 1st and 2nd ports, and both have the same issue- Fire only response from the joysticks (which again are fully tested and work).

 

GTIA again? B&C has them for $5. Should I go for it?

[ClausB]

Thanks for the advice sup8pdct!

You can return the favor by posting your 400's serial number in the thread below!