Help with 7800 problem...

[opcode]

Hi,

 

I just got my first 7800 today in the local flea market. Very nice looking unit.

Anyway, arrived home, hooked up everything, the game appeared on screen. However it has a very annoying video problem. It seems like the video looses sync during frames and the image is displayed shifted every other frame. Usually that lasts for a few seconds then the image stabilizes. It keeps alternating between stable image and out of sync image for as long as you leave the system turned on, no matter which 7800 game I tried.

 

Then I tried some 2600 games. Everything normal, no video problems.

 

Went back to the 7800 games and played for a while. Then the games started hanging after a while. Power off, on, tried again, same thing, freezes after a while.

 

Then I decided to try the 2600 games again, and for my surprise none of them would work, just back screen.

 

7800 games are still working but with the weird video effect. I took a picture so you guys can see what I mean. Not use if it would be my TV, it is a Sony LCD, no problems like that with any other old system.

 

Would it be my Maria chip has gone bad?

 

Thanks,

 

Eduardo

[opcode]

Another observation, pause isn't working with any of the games (by any game I mean Pole Position II and Xevious, the only two I have).

[+Mitch]

Check the 7805 voltage regulator and see if it is outputting a nice clean +5 volts.

 

Mitch

[Kr0tki]

This might be the case of a newfangled TV not quite tolerant of non-standard NTSC signal (non-interlaced) produced by 7800. The problem is prevalent for many old systems. For example there's a topic that discusses known LCD TV's that work with Atari 8-bit computers.

 

So the first thing should be to try another TV, possibly a CRT. Or else - in the above topic, they mention that getting a scan doubler/flicker fixer device might help.

Edited April 19, 2010 by Kr0tki

[opcode]

Thanks for all the suggestions.

I just got a second 7800 and it seems like I actually have two different problems. The sync/interlace problem seems to be related to my TV, because the 2nd 7800 is presenting the same problem. Funny that none of the 2600 games exhibit that.

Now, the first 7800 still cannot play 2600 games, the pause key isn't working and is locking up all the time. It is funny that during its first hour or so it worked flawless. Anyway, next I am going to check the power supply and also the pause switch.

 

Eduardo