Christophero Sly Posted April 9, 2004 Share Posted April 9, 2004 My 2-port is having strange problems on certain games. I think I may have some bad RAM. I have a diagnostic cart (1.1) and it has a RAM test, but I don't have a manual, so I don't know how to interpret the diagnostic outputs. Can anyone help me out with this? I don't even know where to start. Thanks. Quote Link to comment Share on other sites More sharing options...
+Mitch Posted April 10, 2004 Share Posted April 10, 2004 Hav you run the RAM test? If so, what was the error code? Mitch Quote Link to comment Share on other sites More sharing options...
CPUWIZ Posted April 10, 2004 Share Posted April 10, 2004 I'll grab the field-service manual and take a look. Be right back. Quote Link to comment Share on other sites More sharing options...
CPUWIZ Posted April 10, 2004 Share Posted April 10, 2004 Ok, under the error summary screen, you will see 2 numbers. Like this: 00 05 The first number is the error code and the second number is the amount of failures. RAM error codes are: 00 - RAM Chip 1 - U25 (location marker on the board) 01 - RAM Chip 2 - U24 02 - RAM Chip 3 - U23 03 - RAM Chip 4 - U22 04 - RAM Chip 5 - U21 05 - RAM Chip 6 - U20 06 - RAM Chip 7 - U19 07 - RAM Chip 8 - U18 Quote Link to comment Share on other sites More sharing options...
Christophero Sly Posted April 10, 2004 Author Share Posted April 10, 2004 The output on the 'Error Summary' screen dosen't change after I run the RAM test. It stays at "0000". Quote Link to comment Share on other sites More sharing options...
CPUWIZ Posted April 10, 2004 Share Posted April 10, 2004 Maybe it's not the RAM then. Quote Link to comment Share on other sites More sharing options...
Christophero Sly Posted April 10, 2004 Author Share Posted April 10, 2004 Ok, under the error summary screen, you will see 2 numbers. Like this: 00 05 The first number is the error code and the second number is the amount of failures. RAM error codes are: 00 - RAM Chip 1 - U25 (location marker on the board) 01 - RAM Chip 2 - U24 02 - RAM Chip 3 - U23 03 - RAM Chip 4 - U22 04 - RAM Chip 5 - U21 05 - RAM Chip 6 - U20 06 - RAM Chip 7 - U19 07 - RAM Chip 8 - U18 Thanks for looking up that information. I really appreciate it! Maybe it's not the RAM then. So '0000' on the RAM test is basically reporting that "Everything is OK"? I'm getting some very strange problems and the problems occur with multiple copies of the same game. Any ideas for what else might be wrong. I've cleaned everything multiple times. Any chance the RAM could be bad, but the test fails to detect it? Maybe Rev. 1.1 of the diagnostic cart is not compatible with a 2-port. Quote Link to comment Share on other sites More sharing options...
+Mitch Posted April 10, 2004 Share Posted April 10, 2004 Try running all of the tests and see if you get errors for any of the other parts. Mitch Quote Link to comment Share on other sites More sharing options...
Christophero Sly Posted April 10, 2004 Author Share Posted April 10, 2004 Try running all of the tests and see if you get errors for any of the other parts. It dosen't look like anything else is giving me an error code either. Quote Link to comment Share on other sites More sharing options...
+Mitch Posted April 10, 2004 Share Posted April 10, 2004 Very strange, I'm guessing that one of the RAM chips is intermittent and only fails under certain circumstances that the diag cart doesn't trigger but those couple of games do. If that's the case, then the only way to find the failing RAM chip is to use a spare known good RAM chip and swap out each RAM chip on the board, one at a time, until the problem goes away. Mitch Quote Link to comment Share on other sites More sharing options...
JB Posted April 10, 2004 Share Posted April 10, 2004 Or just to cover the VERY basics... This isn't one of the games that doesn't work with the 2-port BIOS, is it? No offense intended. It's easy to forget the trivial stuff like that sometimes. Quote Link to comment Share on other sites More sharing options...
Christophero Sly Posted April 10, 2004 Author Share Posted April 10, 2004 Or just to cover the VERY basics...This isn't one of the games that doesn't work with the 2-port BIOS, is it? No offense intended. It's easy to forget the trivial stuff like that sometimes. Yeah, the problems are so strange that I thought that might be the answer. Ms. Pac-Man -- Starts up, plays the intro tune, then, immediately reports "Game Over". Kangaroo -- Kangaroo randomly falls to its death for no reason. I tested all my 5200 games last night on the 2-port and came up with some other problematic games, which reinforces my belief that it's a hardware issue. Montezuma's Revenge -- After playing for a while, tiles start to get messed-up... score gets garbled and gets displayed in the center of the screen... eventually hangs. Berzerk -- Screen freaks-out when voice is triggered. Pole Position -- Horizontal lines appear randomly in the same location on screen. Very strange, I'm guessing that one of the RAM chips is intermittent and only fails under certain circumstances that the diag cart doesn't trigger but those couple of games do. If that's the case, then the only way to find the failing RAM chip is to use a spare known good RAM chip and swap out each RAM chip on the board, one at a time, until the problem goes away. Any chance that a faulty ANTIC chip could be causing the problems I described above? Quote Link to comment Share on other sites More sharing options...
Christophero Sly Posted April 10, 2004 Author Share Posted April 10, 2004 I cracked open the console and had a look at the RAM in A18-A25. It appears that this console has been serviced in the past. A23, A24, and A25 have replacement chips. The chips in these locations are not 'MK4516N-15' like the RAM in the other 5 locations. A23 and A25 have '4564N-25' A24 has a '4264-15' Could these replacements be incompatible? I'm no expert here, but dosent "-25" refer to the chip speed? Is 250 nanoseconds fast enough? Quote Link to comment Share on other sites More sharing options...
Bryan Posted April 11, 2004 Share Posted April 11, 2004 The bigger problem is that someone installed 64Kbit chips, not 16Kbit like the others. -Bry Quote Link to comment Share on other sites More sharing options...
Christophero Sly Posted April 19, 2004 Author Share Posted April 19, 2004 The bigger problem is that someone installed 64Kbit chips, not 16Kbit like the others. Indeed, it was. I replaced the 64kbit RAM chips with 16kbit chips I got from CPUWIZ, and the console works flawlessly! Thanks to everyone for their help. Quote Link to comment Share on other sites More sharing options...
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