Level42 Posted November 19, 2017 Share Posted November 19, 2017 I think OP is quite capable of making his own decisions. Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted November 19, 2017 Share Posted November 19, 2017 try piggy-backing good RAM chips onto the mT ones to isolate the problem if you do take the soldering iron to the board, be very gentle - the XE range had cheaper assembly costs and the tracks will de-bond if youre not careful best of luck Quote Link to comment Share on other sites More sharing options...
Level42 Posted November 19, 2017 Share Posted November 19, 2017 Yep, that is good advice. It seems to depend on the board....I think the more deep/bright green boards are better at that aspect than the more grey/green looking ones....so it looks like he's lucky but still...be careful. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted November 20, 2017 Share Posted November 20, 2017 generally hot is shorted cold is open, can't hurt to try though 1 Quote Link to comment Share on other sites More sharing options...
Chongo Chile Posted November 21, 2017 Share Posted November 21, 2017 You can use the Sys-Check V2.2, it a piece of art for repair Ataris. You instal it on the atari expansion slot, turn ON the Atari and the Atari will display the bad RAM chips and there location. I make a video of the process, but sorry it is in spanish. 2 Quote Link to comment Share on other sites More sharing options...
dex Posted November 26, 2017 Author Share Posted November 26, 2017 Hello everybody, here I am again. Thank you all for the additional hints! The Sys-Check-Expansion looks very good! I have to search for an option to buy it somewhere. I think this thread can help me probably. I have received the sockets and the first memory chips and replaced them already. I have replaced them all and not only the hot ones just to "feel clean". The board is really very sensitive, I've never soldered something like this and just broke a land but repaired it than. After the sockets were soldered on the board I've double checked the connections beetween the sockets with a multimeter. There seems to be everything OK so far and the chips are not getting hot anymore, only just a little bit warm after some minutes the Atari is turned on. But the Problem is: The screen is still red! I have checked the other chips after some minutes and the warmest chip is the CO14806-12 but it is not getting really hot. It's getting only hotter after several seconds with my finger on it. I'm not sure if this is a problem or not. All other chips are getting only warm, except all the small ICs, the CO14795-12, the CO12294B-01 and the only chip which was on a socket: CO61991-01 – these chips are staying cold. I have removed the CO61991-01 from its socket as you can see on the photo attached to this post. The socket looks like somebody has already removed this chip at least once before. And as you can see there is a bent pin. I think this is not what this pin should look like. Am I right or does this make any sense? Should I try it again after fixing this pin? 1 Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted November 26, 2017 Share Posted November 26, 2017 Absolutely: straighten the pin and try again. The bent pin (A9) could have been the cause of all your issues. 3 Quote Link to comment Share on other sites More sharing options...
dex Posted November 26, 2017 Author Share Posted November 26, 2017 This would be too easy if ... . Nope! Unfortunately the screen is still red. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted November 26, 2017 Share Posted November 26, 2017 Got a spare FREDDIE? Quote Link to comment Share on other sites More sharing options...
dex Posted November 26, 2017 Author Share Posted November 26, 2017 Unfortunately no. Do I have to get exactly one with the same part number or are there any alternatives? Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted November 26, 2017 Share Posted November 26, 2017 AtariMax lists these catalogue numbers: CO61991-29 - NCRCO61922 - CITEL Once you have spares, swapping out anything socketed is a cinch. If you're sure the new RAM is good (and there are no soldering or broken trace issues) and a FREDDIE swap does nothing, you can proceed to trying a different MMU and even OS ROM. The most badly damaged machine I ever worked on (65XEN) had bad RAM, MMU, OS ROM, FREDDIE and 74LS74. Nothing was socketed, but I followed my nose and had lots of spare ICs to hand. Quote Link to comment Share on other sites More sharing options...
Level42 Posted November 26, 2017 Share Posted November 26, 2017 One tip: Are hou absolutely sure your new RAMs are good ? Can you check them in another known working machine ? Are you sure they are inserted in the sockets fully ? Some sockets need quite a bit of pressure to make the RAMs sit perfectly. I've had the same problem when I replaced all RAM on the 2nd XE board and next tried reseating some RAMs and seriously pushing down on others to make them fully sit correctly, After that the machine jumped to life. Oh and also check all pins of all RAMs if they aren't bent and are correct in the sockets. Quote Link to comment Share on other sites More sharing options...
dex Posted November 26, 2017 Author Share Posted November 26, 2017 Thank you both for the hints! OK, this seems to get a longer process. I'll check eBay tomorrow to see what I can get, now I'm too tired. I have some 40 pin sockets and also some 74LS74 chips left. This is what I can do/test while waiting for the other stuff. Unfortunately I'm not absolutely sure if the memory chips are 100 % OK. I bought these chips on eBay, they have been offered as "new old stock" there but I looked today once again on the eBay page and the seller has not mentioned wether they have been tested or not. I'm waiting for another set of OKI chips I have ordered in Bulgaria, I hope to get them in the upcoming week. These chips has been sold as "tested". And I will get an Atari 130XE hopefully this week, too, but I don't know anything about its condition so far. The pins of the RAM chips are all OK, I tried also to press them with a little bit more pressure in their sockets but they didn't move. 1 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted November 27, 2017 Share Posted November 27, 2017 When I am out of drams I always order 10 ram chips at a time when working on 130XE and 800XE... or I find old graphics cards to rip them from and performs the test on all chips before using them in repairs.. 1 Quote Link to comment Share on other sites More sharing options...
dex Posted December 21, 2017 Author Share Posted December 21, 2017 No almost a month later I'm back. Meantime I ordered a "new" Freddie but replaced the existing one in my 800XE but this didn't help. So I've checked again every chips temperature and the CPU (CO14806) seemd to be strange: only the half of the chip was warm. So I have desoldered the chip carefully and soldered a socket. Yesterday I got a new CO14806 and put it in and what can I say? It works! Thank you all for the hints and help! Today it is for me like christmas! Now I have to get a drive to see if this works and then I want to build a DIY SD card drive. I found some tutorials based on the Arduino Uno. 8 Quote Link to comment Share on other sites More sharing options...
shoestring Posted December 21, 2017 Share Posted December 21, 2017 It's a great feeling to get results like these after persevering. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted December 21, 2017 Share Posted December 21, 2017 and once again solved by 'feeling' around! Nice! Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted December 21, 2017 Share Posted December 21, 2017 Congratulations! Nothing quite like running a problem to ground and getting a machine working again! Quote Link to comment Share on other sites More sharing options...
1050 Posted December 21, 2017 Share Posted December 21, 2017 Nice outside the box diagnosis and for the win too. Doesn't get better than that. Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted December 22, 2017 Share Posted December 22, 2017 gratz dude! tenacity is the secret ingredient Quote Link to comment Share on other sites More sharing options...
Level42 Posted December 28, 2017 Share Posted December 28, 2017 Great that you persisted and got it fixed ! And another thing we learned from it too... Sounds like both RAM and CPU were dead then....I wouldn't be surprised if this machine was connect d to either a dead power supply pushing out too high voltage or maybe to a C64 PSU.... Anyway : well done !!! Quote Link to comment Share on other sites More sharing options...
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