traindriver69 Posted November 28, 2014 Share Posted November 28, 2014 Hi all The Atari 400 I had brought off ebay came today but its not working when I plug it in I get a blue screen and when I use the keyboard It puts the letters on the screen but not one after the other and only on the top two lines. I had a look at the atari field service manual and for a blue screen it says change the pokey chip so I swapped it with one from my Atari 800xl which i belive are the same tell me if I am wrong but still the same any help please. Quote Link to comment Share on other sites More sharing options...
sup8pdct Posted November 28, 2014 Share Posted November 28, 2014 Looks to me like a faulty ANTIC chip, or maybe ram. That black line towards the bottom should not be there. Dont swap ram chips with 800xl. The 400 std ram chips have 12v on one of the pins that will fry the ones from XL. I would try swaping antic first. James 1 Quote Link to comment Share on other sites More sharing options...
Rybags Posted November 28, 2014 Share Posted November 28, 2014 Shipping 400/800 has it's risks since neither is a single board computer. Since you'd be needing to pull it apart anyway I'd just pull the boards out, put back in and it might work straight up. But yes, I'd be looking at the Ram and Antic if it doesn't work properly, Pokey has nothing to do with display generation and wouldn't cause the symptoms you have if faulty. 1 Quote Link to comment Share on other sites More sharing options...
tep392 Posted November 28, 2014 Share Posted November 28, 2014 Make sure you clean the contacts on those boards as well. That fixed the DOA 400 I bought off Ebay. Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted November 28, 2014 Author Share Posted November 28, 2014 Could I use the ANTIC chip off the 800xl or would I have to try and get one from somewhere. Quote Link to comment Share on other sites More sharing options...
+Stephen Posted November 28, 2014 Share Posted November 28, 2014 The ANTIC from the 800XL will work fine. Quote Link to comment Share on other sites More sharing options...
ClausB Posted November 28, 2014 Share Posted November 28, 2014 While you have it open, reseat all the ICs in their sockets. That is, pry each up half way out of its socket and then push it back in. That will scrape off corrosion built up over the decades. 1 Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted November 28, 2014 Author Share Posted November 28, 2014 cleaned all contacts reseated the chips and the best I get is this. Quote Link to comment Share on other sites More sharing options...
Rybags Posted November 28, 2014 Share Posted November 28, 2014 Maybe it does have a faulty Antic, or some problem in the memory select logic. That should say ATARI COMPUTER - MEMO PAD but some of the text is repeated or missing. If you have access to a spare Antic then it's worth a try. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted November 28, 2014 Share Posted November 28, 2014 move the ram around.. see what changes... Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted November 28, 2014 Author Share Posted November 28, 2014 that is after changing the Antic with the 800xl although i put the 800 xl together with the 400 Antic and now getting black screen Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted November 28, 2014 Author Share Posted November 28, 2014 Tried changing the memory chips around and now all I get is a black screen on the 400 whichever order they are in its driving me crazy swapped the Antics back around to there original computers and now the 800xl is back and running so does that prove at least the 400 Antic is faulty or would it give you a black screen on a 800xl. Quote Link to comment Share on other sites More sharing options...
sup8pdct Posted November 29, 2014 Share Posted November 29, 2014 Only difference between 400 and XL antic is number bits for refresh. I think latter antics will work in early computers, but not other way round due not to refreshing ram properly. I could be wrong tho. James Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted November 29, 2014 Author Share Posted November 29, 2014 But why since I moved the memory chips around I am getting a blank screen and a beeping noise from the Atari 400 speaker Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted November 29, 2014 Author Share Posted November 29, 2014 I have now took all the chips off the memory board and the CPU board put them all back in again and got the blue screen back again but no text cant type in any letters .if I put in star raiders cart the game boots up and works for a short time then crashes but if I put basic cart in nothing happens.put the ANTIC back in from the 800xl but still the same anyone any ideas please. Quote Link to comment Share on other sites More sharing options...
sup8pdct Posted November 29, 2014 Share Posted November 29, 2014 If you can get a salt cart, plug it in and run ram test. If you cannot get one, I would try another memory card. A long shot is to swap both pia and gtia chips. The processor most likely cannot be swapped over but that depends on how late the 400 was built and if it is PAL or nojames Quote Link to comment Share on other sites More sharing options...
BillC Posted November 29, 2014 Share Posted November 29, 2014 (edited) Check the internal +12/-5V supplies, -5V is used for the power LED and I believe the only other thing both are used for are 8/16 kbit RAM chips on a memory card. If one of these is out of specifications it could be causing memory instability. A complete 48K RAM upgrade for the 400 is only $29.95($25.95 for just the board/jumpers) + shipping from Best Electronics, with one of these installed the only significant difference between the 400 and a 48K 800 is the keyboard and the monitor jack. PS: Instructions on upgrading a 16K RAM board to 48K are attached to the following post: http://atariage.com/forums/topic/109732-atari-400-48k-memory-upgrade/?do=findComment&comment=1326701 Edited November 29, 2014 by BillC Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted November 30, 2014 Author Share Posted November 30, 2014 Sorry to sound stupid but where on the board do I Check the internal +12/-5V supplies Quote Link to comment Share on other sites More sharing options...
ClausB Posted November 30, 2014 Share Posted November 30, 2014 On the 400 PWR board at the long red connector J201 you will see labels -5, +5b, +5a, gnd, +12. Those labels are not white but are green covered metal, so harder to see. +12 is pin 2, gnd is pins 3 and 4, +5a is pins 5 and 6, +5b is pin 7, and -5 is pin 18 of 20. If there is someone nearby with a working 16K RAM board from an 800 or another 400, you could swap it in to see whether your RAM is good. Or upgrade to 48K as posted above. Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted November 30, 2014 Author Share Posted November 30, 2014 Just checked them getting -4.91v at pin 18, 12.18v at pin 2 and 4.89v at pins 5,6,7 so does that sound right Atari 400 are not as common over here so can't borrow a memory to try it will be ordering the 48 upgrade from best electronics but would have liked to get some life out of it as will have a long wait on the parts coming. Quote Link to comment Share on other sites More sharing options...
ClausB Posted November 30, 2014 Share Posted November 30, 2014 Those voltages are good. Do you have any other 4116 RAM chips to swap? Maybe in another old computer? Quote Link to comment Share on other sites More sharing options...
ClausB Posted November 30, 2014 Share Posted November 30, 2014 How many chips are on your 400's CPU board (rearmost vertical board)? If there are 4 then you can swap CPU chips with your XL. If there are 7 then no. Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 18, 2014 Author Share Posted December 18, 2014 Hi all Have now received the 48k upgrade from best electronics soldered the wires and plugged it back in and now the Atari is working but for some reason the picture is getting some bad interference if I plug the old 16k ram board the picture is perfect but of coarse the Atari is not working than because the ram board is faulty.but as soon as I plug the 48k board in the picture is bad. any ideas please. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted December 18, 2014 Share Posted December 18, 2014 You basically have told us the 16k ram board is bad so you can either replace the bad chip on that board or just replace that board. dirty picture.. make sure you have cleaned and re seated everything... check power levels with new boards in... make sure taroids are on all cords going in and out of the 400 maybe some capacitors are not up to the job on the power supply or memory cards.... someone might compare a clean video looking memory card against a dirty video looking memory card and report the differences... Quote Link to comment Share on other sites More sharing options...
traindriver69 Posted December 19, 2014 Author Share Posted December 19, 2014 Just checked the voltage points and they are still exactly the same. Quote Link to comment Share on other sites More sharing options...
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