Atari 1200XL - Corruption on power up

[abeckett]

Hi all!

 

I was fortunate (or not) to pick up an Atari 1200XL at PRGE 2024. As they were not sold in Australia, I took the opportunity to purchase one. Instead of the cascading Atari Logo - I get the noise but this image.

 

i have tested all the RAM chips, fine. Processor clearly works, POKEY is producing audio - could be ANTIC or something else. Looking for advice before I start cannibalising other Ataris to test chips.

 

Thanks for your advice and experience in advance;

 

Anthony

[abeckett]

Ok! 
 

I have a parts 130XE and swapped out the ANTIC. I now get this.

When the keyboard is plugged in, nothing happens when I press any key(s). All I get is this.

 

What does a 1200XL need to get past this point?

 

Anthony

 

[abeckett]

I also just realized I put a PAL ANTIC C021698 to replace a C0122960.

 

Maybe I need an NTSC ANTIC as well.

 

Anthony

[abeckett]

I’m enjoying this conversation with myself. I have ordered a new NTSC ANTIC chip. I guess I still need the question answered about keyboard input and what’s supposed to happen next.

 

Anthony

[cwc]

On the rainbow logo screen I think you need to press the Help key to get to the Self Test. Note that the connection in the keyboard between the mylar and the PCB is a common point of failure in the 1200XL. You may need to do the following to get the keyboard working. I had to do this for both of mine.

 

[xrbrevin]

2 hours ago, abeckett said:

I’m enjoying this conversation with myself

hehe whatever gets the job done i suppose 🙃

 

do you get keyboard clicks? that is the GTIA's responsibility

 

in a nutshell, the CPU writes display data to RAM, the ANTIC accesses it and formulates the instructions for the GTIA to display the image.

 

i think youre in the right ballpark tho, a dodgy ANTIC can tell the GTIA to display dodgy image data and it will just obey without question!

[Rybags]

You'll only get keyclicks if a language cartridge is inserted or you've booted Dos or something else that uses a text screen.

For testing purposes something else like a game or Basic cartridge would be helpful.

 

NTSC Antic - probably not totally critical here but with a PAL Antic you'd probably get a black & white display.

[gilsaluki]

8 hours ago, abeckett said:

I’m enjoying this conversation with myself. I have ordered a new NTSC ANTIC chip. I guess I still need the question answered about keyboard input and what’s supposed to happen next.

 

Anthony

Unfortunately, this is what you get on Atari's Atariage.  DBM.

[Rybags]

Most 1200XL expertise will be in the US since that was just about it's only market.

When this thread was started, most members in the US were probably asleep or not far off it.

This forum just about always has dead periods where there's practically no activity for hours in a row.

[+DrVenkman]

What’s the specific question? I have some personal experience restoring a very badly beaten up 1200XL a number of years ago, and currently own three of them.

 

I can tell you without a keyboard attached and no cartridge inserted, you’ll only get the logo screen. If you can get a keyboard connected, and if it works, the Help key would get you to the self-test screen and you can test the rest of the keys. If the keyboard doesn’t work it’s almost certainly the membrane, which you’ll have to repair or replace. 

 

[flashjazzcat]

3 hours ago, gilsaluki said:

Unfortunately, this is what you get on Atari's Atariage.  DBM.

Not getting responses within one hour when posting from the other side of the world while most of the other forum members are probably asleep is a bad show indeed.

[darwinmac]

7 hours ago, gilsaluki said:

Unfortunately, this is what you get on Atari's Atariage.  DBM.

Ok, you’ve used this acronym forever. What does DBM mean?

 

Bob C

[abeckett]

Sorry guys - meant no offence. The joke about talking to myself was based on the fact that I should have just figured it out myself as I was answering my own questions - not the delay by anyone else.

 

so ANTIC + keyboard Mylar repair makes a difference! I must have a trace not right - will have a look but it is now typing half the keyboard. Great video @flashjazzcat.

 

not bad couple hours work!

[+Stephen]

3 hours ago, darwinmac said:

Ok, you’ve used this acronym forever. What does DBM mean?

 

Bob C

I've asked a bunch of times.  At this point, my best guest is dog's bowel movement.  Because the content usually precedes the acronym   So until further notice, dog's bowel movement it is.

[Geister]

DBM = Don't Be Mad?