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About Trellot

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  1. Might want to check back with that previous TIA chip to see whether or not you have two good chips now
  2. Regarding that second games pic, is that Pole Position? If so, there is definitely graphical corruption there, lol. Take a look, closely, at picture 3 of the solder-side of the board. Locate the RIOT chip (A202), first chip on the top, and notice what looks to be potential damage to two traces leading to pins 23 and 24. That might just be some mask coming off, or if say the board was dropped onto something there could be a potentially severed trace there. I'd run continuity on those traces just to rule them out, then move on to next steps. ~ Trellot
  3. Trellot

    No display

    What does the TV show? Snowy screen, solid black? Double check that your switches are cleaned up and making good contact. Try a different RF cable, etc.
  4. Bahhhah! Try Jupiter Lander and Clown Attack! I grew up with VIC 20, not a bad unit. All this mess and then a VIC 20 in the end, I love it!
  5. That connection to C214 looks pretty wild ! I see the pad is gone for pin3 on the rf modulator pinout. Also, the greenish wire connected to the resistor looks to be touching the pad next to it; might just be the pic but good to double check that.
  6. Thanks Nezgar, yeah I will try to acquire more working pieces for this troubleshooting. I like your neat trick here however! I will try it nonetheless once I have a working unit
  7. Thank you for your comment. I'd very much like to try this process. I do have one cart that could be used, such as the one you pictured above. Questions: 1. Can DOS 2.0 virtualization be used for this process? 2. How do I connect the ROM cart to the computer so that the OS sees it? I've dumped spis and such before but through a USB connection. 3. Lastly, as I'm thinking more about this, I feel like I might need a working Atari 400 for this? If so, I guess this test won't work for me yet, lol. Thanks, ~ Trellot
  8. The bad power side board never even powered the LED, it was just dead, I couldn't get any voltage readings anywhere on the 400... it ended up causing my power supply to blow a fuse. I'll try the RAM swapping too. Thanks!
  9. I'm not familiar with the process you're describing above although I understand the value of this test would be to show that the ROMs still dump some kind of data, is that right? So if I were to conduct this test then any data dumped would show the chip to be good? or would I need to compare my dump to some other known good dump out there? Thanks for your reply, btw!
  10. Yes, I will post my findings as I go. Regarding my Atari unit, it does have the stock RAM module inside. I think my next step is to order new populated CPU/RAM boards and play the substitution game. Even if they don't solve my problem I'll at least have a good set for future repair projects.
  11. So I'm getting 5volts on pin8 of the 6502 chip and .016v on the SYNC pin7. Note: I was only testing with the mainboard and power supply powered up, no other connections. ~ Trellot
  12. Thanks for the response! I'll try the above and post results. I have reseated all the ICs on this unit previously, hoping that'd get be booting but alas... ~ Trellot
  13. Greetings all, Purchased an Atari 400 and all I get is a black/brown screen on the TV; with or without a cartridge. Channel select on 3 as is the TV. Heads up: I am using the following tech manual "Sams_Computer_facts_Atari_400" to troubleshoot from: http://www.atarimania.com/documents-atari-400-800-xl-xe-technical-documents_3_8.html Power supply voltages: (Note: this is the second power supply; first one was bad and I'm currenty recapping it.) CR206 BR Diode -> 11.58v CR208 BR Diode -> 11.79v VR A202 (5v) pin3 -> 5.06v VR A201 (12v) pin1 ->23.86v VR A201 (12v) pin3 -> 12.20v CR201 Zener Diode -> -5.12v Verify Oscillating Crystal on mainboard: (should be 3.579575mhz) X101 -> (using a multi-meter on Hz setting: I'm getting varied results across the board nothing particularly solid and the reading doesn't stay put, it zeros out after holding the probes for a while. Any tech tips on getting a good read on this part? All I have at the moment is this multi-meter. Thanks, ~ Trellot
  14. Could have some funky traces based on your trouble description too.
  15. Have you been able to duplicate this on a second monitor source? Also have you tried both Channels 2 and 3, or even a different RF cable? Are you using a TV Switch Box or an F-plug Female Adapter? That TV might not have very good internal RF shielding and with a troubled TV Switch Box right behind it... You might also try moving your RF cable around to see if anything clears up while moving it. I'm no expert but this sighting's gone stale, maybe this will jump start it lol.
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