Atari 5200 Black Screen on boot

[slacker]

Hi All,

 

So I pulled out my Atari 5200 to test a controller my friend found at a thrift store. The good news is the controller works, the bad news is my system doesn't anymore.

 

I was playing for about an hour before all of a sudden it decided to stop working. When I turn the system on, I get a solid black screen. Before this happened, I was getting some strange video irregularities. The screen for the most part would be okay but it would go into to flashing fits and then level out again. It seems like it got worse the longer a game was played. I thought maybe it was a dirty system/game or the video cable was going bad. Cable checked out okay. I cleaned the games and it made no difference.

 

I found a repair manual online from Atari for the 5200 that had a troubleshooting section for a solid black screen. I took my system apart and pulled out my multimeter. I was unable to check the frequencies of the chips because I believe I need an oscilloscope for that. Checking the voltages where the manual said to, it looks like the voltages were all good except for A26, the 4013 Power ON/OFF latch. Across pin 8 and 16 I was reading around 14v where it should have been 5v. VR1 & VR2 were both showing 5v on their output pin so I'm not sure where this extra voltage could be leaking from.

 

I did notice one larger resistor by the AV box closest to the end of the board was VERY hot. (By Q6, Q7. They're blue with gold, black, red, green brown rings on it)

 

My system is a two port model, so it does not have the power integrated AV box like the 4 port model.

 

Any ideas where to go from here?

 

Thanks!

[quylein]

On several 2 port models I've had issues like this it was either a memory chip or the RF unit itself. The 7805 takes 14v to 9v /dependant on power plug/ makes it 5c. that is supposed to be 5v output on the 7805s.

Another issue can be the flip flop chip if it's not powering both voltage rails. It's cheap 4013 chip near the power switch but 2 ports it's not socketed.

I know the RF box sometimes gets bad solder joints but I don't mess with them much since I AV mod them.

 

Another issue can be

[slacker]

On several 2 port models I've had issues like this it was either a memory chip or the RF unit itself. The 7805 takes 14v to 9v /dependant on power plug/ makes it 5c. that is supposed to be 5v output on the 7805s.

Another issue can be the flip flop chip if it's not powering both voltage rails. It's cheap 4013 chip near the power switch but 2 ports it's not socketed.

I know the RF box sometimes gets bad solder joints but I don't mess with them much since I AV mod them.

 

Another issue can be

 

Ok. So it looks like the 7805's are outputting the correct voltage. I find it strange I was getting 14v at the 4013 chip though. I would have thought that it was down stream of the 7805, thus only getting a 5v input.

 

I'll check online to see if I can pickup a cheap 4013 and try swapping it in. I'm not really comfortable messing with the RF box, but I'll look for any loose solder joints.

 

Also, it looks like your message got cut off before you finished. Was there any other ideas you had?

 

Thank you for your help!

[quylein]

Heh no it was a mistake there.

[quylein]

Did you get any luck with this?