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Everything posted by kb1ujs

  1. Not meaning to necro this thread, but to help those in the future searching out answers to this question. I removed U3 and programmed a GAL to replace it. That made no difference in the behavior. I then ordered a replacement set of RAM chips. I removed the old ones, socketed the RAM locations, and installed the new RAM. The machine now boots to the ready prompt.
  2. Hi all, I have successfully repaired the motherboard on my 800xl to the point where it will boot to the ready prompt. I am in the process of putting the machine back together and realized the space bar is always in the depressed position. If I flip it upside down or lift the keycap it comes up, but gravity pulls it back down to a fully depressed position when I let go. The keyboard mechanism was made by Mitsumi, if that matters. What are my options for fixing this? I'm not seeing an easy way to remove the spacebar. Thanks in advance for any help.
  3. Thank you for the links. Lots of great info there.
  4. I reseated the few chips on the board that are in sockets (POKEY, CPU, ANTIC, and GTIA) with no change. Off to look for replacement RAM and ROMs.
  5. None of the RAM is socketed, so if I replace it I'm going to put machine pin sockets in. The computer came with a modern replacement switching power brick. I am going to test it though as I don't know its provenance. This is the only Atari 8 bit I have, so swapping parts isn't an option. I do have access to test equipment (oscilloscope, logic probe, multimeter) so I'm hoping to get a good enough idea of what's going on to get the right parts
  6. Hi all, I recently bought an 800XL with some issues. When the system is powered on, it immediately boots to the Memory Test. Both ROMs fail the test, and the RAM test only completes two or three blocks before it fails with the screen attached. The keyboard is unresponsive and I need to power cycle the machine to reboot. I'm new to Atari 8-bits but I am confused how the ROMs fail the test yet the machine boots to the Memory Test screen. I would assume based on my limited reading reseating the socketed chips (very few on this particular machine), testing voltages, and ordering up new RAM and RAM sockets would be where to start on getting this thing running again. Am I missing anything else?
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