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JGRAHAM2

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Posts posted by JGRAHAM2

  2. Posted · Edited by JGRAHAM2

    14 hours ago, bob1200xl said:

    How do you know it is bad and how do you know a new chip will fix it? I have some 2797s but I don't know if they are good.

     

    Bob

     

    I switched it out with one from another Indus drive and it resolved the issue. I was getting an H3 error code.

     

    Edit: I have a 2797 coming, so I’ll update this thread when I get it. It is a WD2797A PL

  6. Posted

    1 hour ago, Nezgar said:

    Very nice/clean install. I can't see clearly from the top-down photos, but are there sockets under the OS/BASIC ROM's, or are the multi-ROM adapters soldered directly to the mobo? If so you must be very confident you'll never need/want to remove them again in the future. It would kind of go against the main theme of detachable wires going on. :D

    Thanks. Most 600XLs are fully socketed. All 4 of mine are.

    • Like 1

  7. Posted

    18 hours ago, SS said:

    It's unbelievable how much 600XLs have gone up in price in the last two years!  I got all four of mine previous to 2020 and none of them were more than $75.  The last one was an eBay BIN for $38 in 2019!  ( Admittedly, I did think that one *was* a bit of a steal. :) )  I don't quite know why 600XLs have skyrocketed so much but I'm thinking of doing a RAM upgrade to one of mine and cashing in on it.  

    I have 4 of them too. I bought them as untested and had intended on putting a RaspberryPI in one of them, but I’ve been able to fix them or there was nothing wrong with them, so I have 4 working 600XLs. I have upgraded 3 with UAV, one with 64kb RAM, one 576KB and one with U1MB. The last will likely be upgraded to 64KB SRAM and left as it is otherwise. That upgrade is solder-less and easily reversible.

    • Like 2

  8. Posted

    20 minutes ago, Stephen said:

    Nice - the more I see the 600XL here, the more I am liking the tiny footprint of it.

    And, in my experience, they are usually in almost new condition. I don’t think they got a lot of use unless someone gamed with them.

  9. Posted

    What do you think? It has a 576K RAM upgrade. 4 OS ROMs, 8 cartridge ROMs, and UAV.  I am using DIP switches for ROM selection. I have done better with the opening for the monitor jack. I should have taken more pictures before I closed it up.

     

    80A7D2EC-7054-4630-86AB-6A941BAD4106.jpeg

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    9245509D-FD15-44A1-8A9F-933C04B777BE.jpeg

    • Like 5

  10. Posted

    On 3/3/2021 at 9:45 AM, DrVenkman said:

     it was the 1200XL’s 9VAC lead, which has the same size plug.

    I did something similar only it was my Indus floppy drive. The display went crazy when on the AC supply and then it went black. Fortunately, it was just the fuse in the 1050 supply that blew. The Indus was fine.

    • Like 1

  11. Posted

    On 4/21/2020 at 12:42 AM, BillC said:

    The DP4T rotary switch below looks small from the images, unable to confirm but think the pin spacing is likely 0.1". It's the only one I can find at a reasonable price that's easy to mount.

    https://www.ebay.ca/itm/2PC-10mm-DP4T-Rotary-Switch-Double-4-Position-15mm-Knurled-Shaft-PC-Mount-Switch/111989402572?hash=item1a1316abcc:g:SaEAAOSw9etXQYf-

    I bought these and they work great both in size and function. Thanks!

    • Like 1

  12. Posted

    1 hour ago, JGRAHAM2 said:

    After replacing both sockets for POKEY and PIA with precision sockets, SIO now works. Thanks to all who helped especially DrVenkman who pointed me to the sockets as the possible problem.

    Well, after putting the aluminum cage back together, it again did not work, so I reflowed the power connectors on both the power supply and the mainboard and it is finally stable and back together with the formerly shattered case. Not perfect, but from the front, it looks pretty good!

     

    D2CA9FF0-B853-4F52-8DC2-41CC6CE4CEA3.thumb.jpeg.8b759e91b94fd3a22cde1d7d9d211628.jpeg

    6DC96A3A-021D-49A5-9835-5B92ACD4062D.jpeg

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    • Like 4

  14. Posted

    I did find that the socket for the Pokey chip was as you described. The 28 pin would check good sometimes and sometimes not. It was clear that it lacked spring tension. I replaced it with a precision socket. It is acting different, but is still not working. Pin 28 is looking good now. I’ll work on it again tonight with the scope. I was looking at the field service manual on what I should see.

  16. Posted

    2 hours ago, DrVenkman said:

    As i pointed out to another person with similar issues, the cassette MTR control line is handled by PIA. Everything used in disk access or any other serial I/O though an SIO2PC, SDrive-MAX, etc is via POKEY. 

    Thanks, that is why I tested with the cassette recorder. I have verified that both Pokey and PIA are good based on switching them out with a spare board and testing there. (Spare board is an 800XL)

  18. Posted

    I looked at the schematics and there is not much between the SIO port and the PIA and POKEY chips. Some resistors and capacitors. The resistors check fine in circuit. Capacitors are harder to check, but they are not shorted. The power board/ mainboard connector looks good. I ran Super SALT, but I don’t have the test fixture or “SIO shorting plug”, which I assume is a loopback, does anyone have a wiring diagram for that?

  19. Posted

    On 3/6/2021 at 8:00 AM, JGRAHAM2 said:

    Thanks, I will do this later today and report back here.

    I checked the resistors and all look good. Continuity looks good. Voltages look good at the power board/mainboard connector.

  20. Posted

    9 hours ago, JGRAHAM2 said:

    Thanks, I will do this later today and report back here.

    I checked the resistors and all look good. Continuity looks good. Voltages look good at the power board/mainboard connector.

  21. Posted

    13 hours ago, sup8pdct said:

    Check out R168 - R174. Make sure they are 100ohm.

    Check out strip resistor R129, 4.7 kohm pullup. make sure one hasn't done something stupid.

    Assume keyboard works so can rule out IRQ not working.

    also check continuity between mother board and SIO connector, make sure the powerboard connector is ok.

    Thanks, I will do this later today and report back here.

  22. Posted

    43 minutes ago, ACML said:

    Just had the same thing happen on my 1200XL two days ago.  Replaced POKEY and PIA and that did not fix.  As a last resort, I blew compress air over the board and under the sockets and "BAM!" it works great.  This is the second time I've had this issue on two different machines and both times, compressed air magically made them right.  I have no idea why, but it worked twice.  Same issue, everything worked, but no boot on SIO.  Go figure.  I used canned air for electronics.  Shop air might have too much static electricity.

      

    I wonder if you had something conductive shorting something out and the air dislodged it. I had an issue recently with a 130XE and it was a bit of solder. 

  23. Posted

    32 minutes ago, TGB1718 said:

    Check inside the SIO socket in case anything is across the pins, Check the SIO socket solder joints on the motherboard, re-flow with solder.

     

    I did that and no difference. I, at first, thought Pokey or PIA, but tried both and that’s not it.

  24. Posted

    I have an 800 that works great, except for SIO. It will not boot from an S-Drive Max or FujiNet even if they are externally powered. I have tried to replace all daughter cards with spares and also all major ICs on the motherboard. Anyone have any ideas on how to troubleshoot?

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