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Posts posted by [email protected]

  1. Posted

    Picture is attached, thank you

    I thought the Key-cap can be pulled-up? There is a metallic "guide" on the Shift key that's not present on most of the other keys.

    I think the switches are the same for all keys.

    I haven't de-soldered any of the keys on this keyboard, so I'm not sure how big of a deal it is to remove just the switch?

     

    They key-cap will not stay with the switch, if you pull it up and wiggle the little metal out.

     

  8. Posted

    I just bought a 520st (one of the models with Video Modulator).

    I hooked it up to a TV via RF cable and got a screen that looks like the attached image

    I also hooked up pin 2 and 13 via an RCA and got a similar image.

     

    What are the chances that the un-modulated output will work (to a VGA monitor that can support 15khz). I do have a Dell 2001fp that should work, I would just need to invest about $40 in a cable.

     

    Any ideas what might be wrong with my 520st?

     

     

    post-52816-0-27425400-1521208597_thumb.jpg

  9. Posted

    Screenshot #2 shows self test in music mode so BTDT.

     

    I've seen such garbage characters corrected by dropping

    in a HCT08 for the standard 74LS08 at U18. This tells

    me that it's something to do with timing and/or not so

    square edges on system clock signals. Ram is of course

    also involved but the root issue is the system timing

    is tad bit off by perhaps a weak LS08 chip. One could

    piggyback one onto U18 if it weren't for the useless

    factory mod involving the pink and purple wires getting

    in the way there. Just as a temporary test of course,

    good results would dictate a proper entire replacement

    then.

     

    You could even remove the factory patch pink and purple

    wires by restoring a cut trace on the bottom side of the

    board and tossing these famous wires in the bin. It won't

    make a hill of beans difference either way. It's GTIA's

    chip select signal from the MMU IIRC.

     

    I've never had to put one back whenever I've taken the time

    to remove that factory patch. Highly suspect that management

    made this fix up just to keep the repair team busy with

    work stacked to the ceiling instead of letting them sit

    around reading novels and having food fights.

     

    The GTIA chips is not the issue - got a replacement one and the 130xe has the same behavior.

    I'll look over the other suggestions this weekend. I might just put it on ebay - too bad as the case and keyboard is pristine...

  10. Posted

    also cut the two caps near the sio connector c 304 c 303, you sio devices will love you for it.

     

    there appears to be a modification above the Atari pcb inlay next to the keyboard post and silk screen... I don't have that on mine.

     

    so do the re-seating touch up bad joints with leaded solder, and start the ram checking....no doubt it'll come back to life...

     

     

    Thanks for all the replies. I ordered a GTIA chip from eBay, hopefully this will be the culprit.

    If it was RAM - wouldn't the computer go to self-test (RAM test)?

    I can actually get to the READY prompt / Basic - and start typing - video is distorted (as shown in my first picture).

     

    I did reseat the MMU and GTIA - no change in behavior.

  13. Posted

    I purchased Atari 130xe - it powers up but has a video issue - basic screen flickers, self test runs but screen has lots of odd characters.

    Any idea which chip to start with?

    Sound works fine. Power supply is NOT an issue, as I have 2 - both of them work on my 800xl, not on this 130xe

    Couple of pics attached.

     

     

    Thanks

    post-52816-0-86782000-1510329074_thumb.jpg

    post-52816-0-86615800-1510329094_thumb.jpg

  14. Posted

    The keyboard itself is fine - I pulled a keyboard from a working 800 and installed it on the defective motherboard - the working keyboard did not respond.

    I'll buy the 4051 on ebay - this should work?

     

    https://www.ebay.com/p/Texas-Instruments-CD4051BE-Multiplexer-8-Channel-16dip/1200436875?iid=282437169279&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D48740%26meid%3Db77ae6b4c40a4497aedc2fb862fea0bf%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D322795851890&_trksid=p2047675.c100005.m1851

  16. Posted

    I have an Atari 800 with keyboard that is not responding at all. I tried another keyboard - same issue.

    The issue is not with a keyboard - must the motherboard or the chip that controls the keyboard.

     

    What would you check first? Computer otherwise boots fine. Start/Select/Option/Reset buttons appear to work.

  23. Posted

    I have a 1050 drive hooked up to 800xl.

    The 1050 has an odd power issue.

     

    When I first plug in the power supply to the outlet, the drive will power up, but won't spin up. The 800xl will not detect it when booting up (holding option when starting up just goes to self test).

     

    When I wait about 5 minutes (after the 1050 has been plugged in to the outlet), the dive works reliably.

    Note, the drive switch can be in the off position, as long as it is plugged in to the outlet, it will continue to work.

     

    Any ideas where I should start looking? Would like to get it fixed, so it won't need to "warm-up".

     

    I'm using original Atari Power supply.

     

    Thanks.

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