IBM 5170 AT Full Restoration Project

Discussion in 'Retro & Arcade' started by Flamin Joe, Apr 29, 2018.

  1. OP
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    Flamin Joe

    Flamin Joe Member

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    A little update. In the words of Borat, great success!

    I was in the right area for the point of failure but as it turned out it wasn't the keyboard controller but in fact the MC146818P RTC. I can't believe I didn't see this sooner but here's a close up of the picture I posted above with the motherboard on the bench. Notice something metal wedged between one of the caps and the MC146818P RTC chip?


    Click to view full size!


    Removing it made no difference however I couldn't rule out that it damaged the chip so I set about checking it with my logic probe. Sure enough comparing it's readings to the 5170 logic chart it was not functioning as expected. Not having any spares I decided to desolder the MC146818P from the other dead board I have and then desolder the chip on the new board and put a socket in it's place. After inserting the new chip and firing it up with the original IBM ROM's I'm greeted with this...:thumbup:


    Click to view full size!


    Side note, I forgot I brought this little 8" portable LCD TV a few years ago. Really handy to use for testing on the bench as it has Composite/S-Video/VGA and of course Antenna which is pretty much useless now (although come to think of it you could possibly use it on a Atari 2600 for example). A lot easier to move around and takes up a hell of a lot less room than a CRT! It's using the IBM CGA composite output which is why there's "snow" on the screen.

    Things I plan to do next:

    Get the RAM back up to 512K. One came up faulty in the initial testing and I have plenty of spares so it shouldn't be too hard to sort out.

    Once bitten twice shy. I know I was extremely unlucky that a failed tantalum on the serial card caused damage to the first board but I'm not taking any risks. As a general rule I'll be looking to replace the tantalum filter caps on any cards I intend to use starting with the ones for this build. I know tantalums are generally very reliable but working with components which are 30+ years old I've seen my fair share of them pop.

    Once these are done I will be back to putting everything in the case once again which reminds me I will need to do something about the power supply too which is in need of repair.

    Also need to get stuck into the 5153's power supply of which it's repair was put on hold.

    And the hunt for more parts resumes......It's like it's never ending. :)
     
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    Flamin Joe

    Flamin Joe Member

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    Received a few more goodies last week but mostly stuff I already had. From the one seller I picked up a Seagate ST-4038 (to replace the CMI 6426 that isn't working), a second YD-380 1.2MB Floppy Drive (to fill the gap due to missing a drive cover) and the original IBM MFM and Floppy cables. All of these were removed from a 5170 the seller was parting out.

    So I grabbed a board I had handy and put them all on the bench with the IBM Fixed Disk and Diskette Drive card.


    Click to view full size!


    First little issue was while the Floppy Drive booted off a boot disk I had already made a while back, when I tried to run SpeedStor to configure the drive it had read errors. Easily fixed as after running a drive cleaner disk to clean the heads it is now reading disks perfectly.

    Now onto testing this beast...Just look at all the circuitry that is on this thing. I should of taken more photo's of it but the top and bottom PCB's on this HDD are just covered in various, IC's, resistors, capacitors the works. All this on a modern HDD is just one little PCB and a few chips.


    Click to view full size!


    Click to view full size!


    So after configuring the drive with SpeedStor I gave it a quick Seek Test which gave it a good work out and as you can see all tested passed. Looks like I've got a winner.


    Click to view full size!


    I was going to do further diagnostic tests but I didn't want to risk wiping the data as some of the tests are destructive. It was reporting an active DOS partition on the drive so I was curious to see what was on there so after a quick reboot...


    Click to view full size!


    Just a clean install of IBM DOS 3.10, nothing interesting at all. Would of been cool to find some old games on there or some software from that era but oh well.

    I must say I'm amazed that this drive still works after all these years and the distance it has traveled to get to me. If the date stamp is correct, this drive was built in Week 25, 1986 so it will be turning 33 years old this June! Like the saying goes, they don't make them like they used to!
     
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  3. matz

    matz Member

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    Nice work, my 5170 is not too far down the list of projects, following your adventures with great interest.
     

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