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xrbrevin

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Everything posted by xrbrevin

  1. thanks for the response. if you could upload the schematic that would be great. I am aware that a number of DRAM pins are common between the whole group but some are not. Id just like to be as clued as poss before getting the multimeter out
  2. A ROM can be replaced with an EPROM if have a burner? RAM chips can be piggybacked to identify the faulty culprit
  3. Very homebrew looking indeed but high speed SIO is a great mod! Is the 800XL an 800XL'F' model? i.e. it uses the Freddie chip for memory management? I only ask because i spotted the mysterious plastic blanking plate at the back of the case that the F models seem to have.
  4. I am trying to revive an aftermarket 32k RAM board for my 400. It is the type that uses 16x 4116 DRAMs. I desoldered and socketed all the chips and found 1x 4116 chip was at fault. My TL866 EPROM programmer says that all the 74LS chips are good but the board still fails to boot. As these PCBs are not the best quality, I'm wondering if I lifted a track that would need to be bridged. Does anyone have a schematic diagram for a 16x 4116 chip type 32k board? I need to do continuity checks across the DRAM pins but i could do with some knowledge before I commence. Thanks in advance!
  5. it would be a great little device if, like you say it could do over disk 100 images is there any way of contacting the designer to see if he can make a Mk II version?
  6. try to read the disks with another drive if you can the alternative is to record the games onto working blank disks, remove the actual disks from the sleeves by breaking the bond. swap them over then glue the flap back down
  7. there are many options depending if you have soldering skills, do you want extra ROM slots too.. check the profile of user: @tf_hh check lotharek's site a device called 'antonia' replaces the CPU and gives you selectable RAM and ROM versions/types there are others that give you a fixed 256k, 320k, 576k, 1088k but the more modern upgrades allow you to select between any of these.
  8. there is a reset switch detailed in the attachment but i dont know how itll affect the Happy mod Atari Drive Select and Reset.zip
  9. Such a sad loss for the community, his contributions were immeasurable and will not be forgotten. Best wishes to his friends and family.
  10. I have a TL866 and ive occasionally used that feature. altho, it has never found a bad 74LS thus far so im unsure if its accurate...
  11. Might be worth trying another screen first if you can, just in case the cable is good
  12. Thanks for the suggestions. I have a logic probe and the back of the RAM board is accessible so i'll have a mooch about. I thought maybe i would take a macro photo of the PCB and then zoom in on the computer to check if any traces are in amiss. On the 32k board I did some continuity testing across the DRAMS and all lines appear to be behaving as they should. All address lines are linked, -5v 12v 5v and GND are linked with no crossovers. RAS and CAS lines are linked but only on every other chip, i assume this is due to it being 2x16k on a single board. If the worst comes to the worst, i will salvage the 4116s and make my standard Atari RAM board into a 32k one. These '80s aftermarket PCBs dont have a silkscreen and the traces are less than robust!!
  13. Can anyone give me any pointers as to how to diagnose a 400/800 RAM board? I have a 48k one and a 32k one and i feel ive done all that i can with them but I just keep getting the red/brown screen. ive checked traces for continuity where there should be and shorts where there shouldnt be. Ive checked the 4116 DRAMs work in a standard board and ive checked that the 4164 DRAMs work in an XL. The 48k one receives it's SEL4, SEL5, A14 and A15 connections from the Z103 socket (via a small piggyback PCB) and it also gets the RD4 and RD5 from the cartridge socket (via 2x wires). Does anyone know of a procedure for troubleshooting? Im wondering if the 74LS glue logic is at fault. cheers!
  14. Tracopower is a good make: 5v: https://www.ebay.co.uk/itm/TRACOPOWER-TSR-1-2450-CONVERTER-DC-DC-1-Output-5-W-5-V-1-A-Fixed/171119461528?epid=149085216&hash=item27d783c498:g:XP4AAOSwgQ9ViYN9 12v: https://www.ebay.co.uk/itm/TRACOPOWER-TSR-1-24120-CONVERTER-DC-DC-24V-12V-1A-SIP/171948241143?epid=149091254&hash=item2808e9f0f7:g:vCkAAOxyXzxTIip~ you can also get cheaper ones from china if you like
  15. they work fine, ive done a few now and as Mytek said, no heat! 😎
  16. you should be fine, ive used files from atarimania without issue give it a go! here is another great site - with a "download all" option! http://www.mushca.com/f/atari/index.php?idx=0 😁
  17. i plan to do an AV mod to the machine first, then i will tinker with the 32k board. i will reflow all contacts and if that fails i will desolder the ICs and test them in a (socketed) 16k board shouldnt be too complicated to get it running, no other mods are needed on a 400 unless you exceed 32k.
  18. yes good idea, and use tweezers to lift out the remains of the cut pins
  19. Be patient when desoldering XE PCBs - make sure the chip pins are loose before you prise the chip up. Some were built at a lower cost and their traces can easily lift.
  20. here is an unbranded 32k board using 16x 4116 chips. I obtained it inside a 400 but sadly it doesnt work.
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