Atari 7800 not loading 2600 carts

[shear_xear]

Hi everyone.  I have an Atari 7800 board that was in my pile that needs repair, and it won’t load 2600 carts.  I swapped out the TIA, and it was loading Frogger only (which I know is a little different from most 2600 carts, and will load when others won’t), and it loaded several games, but I noticed that the a few legs were bent and not in the socket, and after fixing that it again wouldn’t load the carts.  Does anyone have a guess as to what to look at? I tried several working TIA and still nothing.  Is there anything else that I could look at?  All 7800 games load normally.  Thanks!

[DanBoris]

On 4/1/2022 at 8:51 PM, shear_xear said:

Hi everyone.  I have an Atari 7800 board that was in my pile that needs repair, and it won’t load 2600 carts.  I swapped out the TIA, and it was loading Frogger only (which I know is a little different from most 2600 carts, and will load when others won’t), and it loaded several games, but I noticed that the a few legs were bent and not in the socket, and after fixing that it again wouldn’t load the carts.  Does anyone have a guess as to what to look at? I tried several working TIA and still nothing.  Is there anything else that I could look at?  All 7800 games load normally.  Thanks!

Do you remember which pins were out of the socket? That might provide a clue to what is wrong.

[shear_xear]

Hi.  I’m not sure exactly, but three in a row somewhere between four and nine. I’m thinking it was pins four, five, and six, but not positive. 

[+Stephen Moss]

If you have not already done so you might want to use the search facility for other threads on the issue, I am sure I have seen a couple recently, one is here.

I think I mentioned this in the other recent thread (not the one linked to above) so it may be worth finding as there might be more information there, but if you do not already have it get the schematic from here.

The check that the TIACS signal is going Low (0V) both when leaving MARI and arriving at TIA as the 7800 detects the cartridge type so if 2600 carts are no working it could be a problem with the cartridge detection or MARIA not enabling the TIA.

 

Could you be a little more descriptive with regards to "not loading 2600 carts", are you getting a black screen and no audio, audio but no video (on carts with an attract mode/start up music), static screen as though there is no power as it may help narrow to eliminate some things.