Atari 1 System Issue

[ricotalbot]

Have you guy's ever seen this issue on an Atari 1 System, it's like the words are scrambled and I can't make out the error. Any Ideas to where to look

 

[Funhouse71]

Is that error appearing with cartridge or without?

 

[GadgetFreak]

Good question

It looks like a Ram Error to me but the address is not right due to corruption. Could be screen ram.

 

[ricotalbot]

It’s when the cartridge is in, if I remove it it does come up with the default no cartridge but this also has scrambled letters so I’m guessing it’s the main PCB? Just to sure where to start, where is the screen ram on these?

 

[GadgetFreak]

You could try my ram tester:
http://www.ukvac.com/forum/topic360268.html

 

[GadgetFreak]

Tip: Even with bad screen ram it should still work but you may have to just look for a colour change on a particular line and then check with the display posted in the thread to see which chip.

 

[Funhouse71]

You could try my ram tester:
http://www.ukvac.com/forum/topic360268.html

I must admit I forgot about the ram tester rom. I ended up programming the original rom and the test rom on a double sized Eprom so I could switch between the game rom and the test rom via a switch...needless to say Rich, if Aaron is on the case then your in safe hands

 

[ricotalbot]

Hey guy's thanks, I was just checking the voltage out of my original System 1 power supply, there are 5 fuses in this bank and 1 of the 5 I don't get anything and the fuses I have checked, does someone have the layout of what voltage I should be getting from all of the 5, there is also a main one and this is fine.
Maybe this is just a voltage problem that is causing this scrambled screen. Thanks as always.

 

[Funhouse71]

Be easier to check what voltages you are getting at the big white 12 pin block connector (P101) on the main board

 

[ricotalbot]

OK cool let me check this thank you as always

 

[ricotalbot]

What’device can I buy to test the ram on the Atari system 1