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XT Clone Floppy issues: Vendex Turbo-888-XT

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    XT Clone Floppy issues: Vendex Turbo-888-XT

    With the college semester over, I finally have time to dig in and fix my Vendex Turbo-888-XT. I received it with an RTC battery already eating away. After clipping and removing the leads, cleaning the board, and replacing a 33pf tantalum capacitor I was able to get life out of the system.

    As you can see in the photos, the system is unable to read the floppy disk with the head failing to even budge. I have confirmed the stock drives and my own written disks (formatted in 360k) work in my 486. The 486 even tried to boot to it... I even tried purchasing an IBM floppy controller which gives the same result: drive light on, spins, and finally a disk bad error.

    Does anyone have any tips on getting the old guy to boot? On a possibly related note, should I clean that spot corrosion more? It is only limited to that area now. If it turns out I do not need the IBM controller card, I will happily mail it out to someone for their assistance.
    Attached Files

    #2
    Have you tried a different ribbon cable? The motherboard doesn't look too bad, I've seen worse. Have you tried the controller in a different slot? Do you have a bootable hard drive? Wondering if the machine will boot from hard drive or if there are possibly other problems as well, which would indicate bad trace or component.

    Comment


      #3
      Cleaning the corrosion will not correct any damage done to the board if there is any. You need to verify the traces and if there are any bad ones they will need to be repaired.
      PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

      Comment


        #4
        Originally posted by twilliamc View Post
        unable to read the floppy disk with the head failing to even budge.
        Does the drive light come on and the motor spin when it is supposed to be accessing the drive?

        With the power off, manually push the floppy drive head toward the center of the drive. At some point it should seek track zero. If it still just sits there, that suggests a mechanical problem, and probably needs cleaning.

        As mentioned, cables can be an issue. Does this use a flat of twisted cable? Make sure A:

        What version and OEM of DOS are you trying to boot?

        Comment


          #5
          Thank you all for your replies!

          1. Traces: While I cannot speak for all. I see no break in any and the traces I have tested with my multi-meter are okay.

          2. Cable: The computer included a flat cable which goes from the motherboard to the drives. I am currently using the IBM floppy card in place of the onboard FDC. The IBM floppy card has a cable with a twist. Following instructions on minuszerodegrees I configured the drive for testing which is how I got the same results on the motherboard. Rather than complicate things. I have the terminated 360k drive that I tested in my 486 hooked up alone at the moment.

          3. Drive activity: The light and motor only come on when it tries to access the drive. The even pushed to the center, the head does not move. This is the same original drive that operated fine when I tested it in my 486.

          4. OS: I am using an image I downloaded specifically for the Tubro-888-XT which has DOS 3.20.

          5. Hard disk: I have an XT-IDE card in my 286. I robbed it and put it in the XT. The XT now said "Waiting for drive to spin up". Then goes to seek the floppy after since I have no drive installed. I have a 32MB CF card I can try to install DOS on via the 286 and see if that boots the system...

          I do have a question about the jumpers. I have two sets of 1-8 jumpers. One on the board and the other on the CPU card. Should these be set the same? I currently have them both set to 1 Floppy disk drive.

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            #6
            It should be a 360kb floppy drive, and jumper 7 and 8 should be on. With me how I configured one drive operation is 1 OFF, 2 ON, 3 and 4 OFF, 5, 6, 7, 8 on.

            Regards,

            Dennis

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              #7
              As a quick update. I purchased the service manual on ebay, scanned, and uploaded it to archive.org: https://archive.org/details/turbo-888-xtservice-manual Lots of useful information there.

              The cable is a flat cable, no twists.

              Using it I was able to reset the jumpers to factory and restore individual access to the floppy drives. My XT-IDE now tries to seek A or B (lights up, disk spins, no stepper motor movement though) when called. Before it would seek both at the same time. I am now working my way through traces to see if I have continuity between the FDC and its required chips/connections. I have a theory the floppy cable might be bad due to the corrosion, possibly a short to ground on the 5v rail too though.

              Comment


                #8
                Originally posted by twilliamc View Post
                As a quick update. I purchased the service manual on ebay, scanned, and uploaded it to archive.org: https://archive.org/details/turbo-888-xtservice-manual Lots of useful information there.
                Thanks. I OCR'ed the document, added bookmarks, rotated some of the schematic pages, then added the result to my web page at [here].

                Comment


                  #9
                  Originally posted by twilliamc View Post
                  Thank you all for your replies!
                  Have you made any progress here?

                  Oddly I too am trying to get my Vendex 888-XT up and running. My on-board floppy controller seems to work fine and I have a single 5.25 bootable floppy. My challenge is that I would really like to DISABLE the on-board floppy controller and use a high density floppy controller. I have one that uses Sergey's ROM and I also have an XT-IDE - in fact several. I know the floppy controller and the XT-IDE work because I can use them in another machine. I have some corrosion around my battery but the PC works, memory tests, and boots to a floppy. The Floppy controller and Gotek also works in combination because I tested in another machine. When I try to use the floppy controller in the Vendex, it tries to access both the 5.25 on-board and the gotek at the same time - if I disconnect the floppy from the motherboard then nothing happens. The ROM for the Floppy controller loads because I can change all of the configuration. The XT-IDE ROM also loads but won't recognize ANY CF drives - even ones that I know work in other systems. I hope you fix your floppy issue and move on to trying to get an XT-IDE running in this particular machine because I am just simply stuck.

                  Chris


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