philgood1351fr Posted September 22, 2021 Share Posted September 22, 2021 (edited) Hi, checked what have already been discussed here with no luck so I ask you my friends for advices.... My 130 XE always boots on Memory test. the 2 ROMS are OK, but RAM is all red except 4. Unsoldered the 8 chips, put supports then tried with differents chips according to what I read here in past topics. Tried with KM 4164-B-10, TMM 41256AP-12, TMS4164-20NL chips but no luck (same results on tests). Diodes are all ok (5v). Tried to swap 1st 64 bank with 2nd 64 bank by crossing resistors R110 and R111 but black screen. Anyone can help on this ? Are my replacement chips are the good ones ? I checked the MT4264 voltage, and notice that I have 5v on some pins and 3.6 on some other. Even 1 pin (pin 3 or 4 that have 1.9 and this one has a dropping voltage during the Ram test). Anyone have the correct voltage for each memory pin ? Thanks for your advices. Phil Edited September 22, 2021 by philgood1351fr Quote Link to comment Share on other sites More sharing options...
TGB1718 Posted September 22, 2021 Share Posted September 22, 2021 (edited) The only pin guaranteed to have +5V on it is pin 8, the power supply pin, all the others are switching on and off at different speeds hence the varying voltages you are seeing. You will not be able to measure voltages on any of these pins with a voltmeter, you need a scope. Could be an MMU problem or Freddie chip Edited September 22, 2021 by TGB1718 Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted September 23, 2021 Share Posted September 23, 2021 yes im thinking freddie too Quote Link to comment Share on other sites More sharing options...
philgood1351fr Posted September 23, 2021 Author Share Posted September 23, 2021 ok thanks a lot. I suppose it's the same chip on the 800XL ? If so I'll be able to switch as I have 3 Atari 800. Thanks a lot for the tips. Phil Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted September 23, 2021 Share Posted September 23, 2021 only the very late 800XLs were made using the Freddie chip, then all the XEs Quote Link to comment Share on other sites More sharing options...
Beeblebrox Posted September 23, 2021 Share Posted September 23, 2021 (edited) @philgood1351fr You can get a new Freddie chip here:https://www.ebay.co.uk/itm/124704063542 Also BTW I got me one of these DRAM testers which has proved most useful for checking all my 16pin DRAM chips (right socket): https://www.ebay.co.uk/itm/124726020732 Edited September 23, 2021 by Beeblebrox Quote Link to comment Share on other sites More sharing options...
Beeblebrox Posted September 23, 2021 Share Posted September 23, 2021 1 hour ago, xrbrevin said: only the very late 800XLs were made using the Freddie chip, then all the XEs Yup, far as I am aware only the Atari 800XLF boards and then XE models have s Freddie chip. Quote Link to comment Share on other sites More sharing options...
philgood1351fr Posted September 23, 2021 Author Share Posted September 23, 2021 Right. Thanks. I bought the DRAM tester and the Freddie Chip. ++ 1 Quote Link to comment Share on other sites More sharing options...
Beeblebrox Posted September 23, 2021 Share Posted September 23, 2021 4 hours ago, philgood1351fr said: Right. Thanks. I bought the DRAM tester and the Freddie Chip. ++ @philgood1351frCool. Make sure with the DRAM tester (if you bought the one I linked to above), that you read the instructions and test DRAMs the right hand socket. If you put them in the left one you can fry the likes of 4164 and 4264 chips, etc. I taped over the left socket to stop any accidental usage. (Just don't trust myself). The only instructions you get on that Ebay link is in the listings - they don't include them with the unit. Great re Freddie chip. good luck Quote Link to comment Share on other sites More sharing options...
philgood1351fr Posted September 23, 2021 Author Share Posted September 23, 2021 (edited) Yes, I printed the manual on Ebay. And I saw the difference between left and right test pins. Pretty sure I'll put a blank scotch over the left one too as I mainly tests 5v chips.... here is the complete manual if needed. Thanks. DRAM_Tester_UserGuide.pdf Edited September 23, 2021 by philgood1351fr 1 Quote Link to comment Share on other sites More sharing options...
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