SEEK Errors on a SHUGART 851 - CP/M

This is a discussion on SEEK Errors on a SHUGART 851 - CP/M ; I have a Shugart 851 that is giving me SEEK Errors the Heads don't seem to be stepping. I also have an 850 that does the same thing Does anyone have any Insight on this Problem. I checked all the ...

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Thread: SEEK Errors on a SHUGART 851

  1. SEEK Errors on a SHUGART 851

    I have a Shugart 851 that is giving me SEEK Errors the Heads don't seem
    to be stepping.
    I also have an 850 that does the same thing
    Does anyone have any Insight on this Problem.
    I checked all the Jumpers, Trying it as B: [jumper set accordingly].
    Also have a Terminator plugged in.
    I know the connections are OK as I can swap in another drive and they
    all work OK,
    TIA
    Bob in Wisconsin
    USE
    trebor72@execpc.com

  2. Re: SEEK Errors on a SHUGART 851


    "Robert J. Stevens" wrote in message
    news:1rCdnW7QssjbR_nVnZ2dnUVZ_t_inZ2d@posted.choic eonecommunications...
    >I have a Shugart 851 that is giving me SEEK Errors the Heads don't seem to
    >be stepping.
    > I also have an 850 that does the same thing
    > Does anyone have any Insight on this Problem.
    > I checked all the Jumpers, Trying it as B: [jumper set accordingly]. Also
    > have a Terminator plugged in.
    > I know the connections are OK as I can swap in another drive and they all
    > work OK,
    > TIA
    > Bob in Wisconsin
    > USE
    > trebor72@execpc.com



    Bob,

    It could be mechanical. I've had a few stepper motors die on me and the
    best defense I've found is to keep them clean, corrosion free, lightly
    lubricated, and a stock of backup drives just in case.

    -John



  3. Re: SEEK Errors on a SHUGART 851

    On Fri, 27 Jun 2008 07:16:51 -0500, "Robert J. Stevens"
    wrote:

    >I have a Shugart 851 that is giving me SEEK Errors the Heads don't seem
    >to be stepping.
    >I also have an 850 that does the same thing
    >Does anyone have any Insight on this Problem.
    >I checked all the Jumpers, Trying it as B: [jumper set accordingly].
    >Also have a Terminator plugged in.
    >I know the connections are OK as I can swap in another drive and they
    >all work OK,
    >TIA
    >Bob in Wisconsin
    >USE
    >trebor72@execpc.com


    Ok. what FDC is driving the Floppy? What is it doing when it reports
    a seek error? For example is it doing a recal (seek to 000)?

    If you have another and it's work the obvious answer is it's broken.
    Likely breakage is grease turned to goo or no read.

    Allison


  4. Re: SEEK Errors on a SHUGART 851

    no.spam@no.uce.bellatlantic.net wrote:
    > On Fri, 27 Jun 2008 07:16:51 -0500, "Robert J. Stevens"
    > wrote:
    >
    >> I have a Shugart 851 that is giving me SEEK Errors the Heads don't seem
    >> to be stepping.
    >> I also have an 850 that does the same thing
    >> Does anyone have any Insight on this Problem.
    >> I checked all the Jumpers, Trying it as B: [jumper set accordingly].
    >> Also have a Terminator plugged in.
    >> I know the connections are OK as I can swap in another drive and they
    >> all work OK,
    >> TIA
    >> Bob in Wisconsin
    >> USE
    >> trebor72@execpc.com
    >>

    >
    > Ok. what FDC is driving the Floppy? What is it doing when it reports
    > a seek error? For example is it doing a recal (seek to 000)?
    >

    Allison;
    I am using my CompuPro 816 with a DISK1A.I have a program DUF05 that runs under CP/M 2.2 and it has an OPTION to display the Disk to the screen. If I Make sure the Heads are fully retracted it will keep displaying Track Zero Over and Over. Guess it doesn't check to see if it stepped.

    Trying to format a Disk gets a "Seek Error". I am trying to get a
    schematic then I can check the IC that drives the stepper for failure.
    If the Stepper itself has failed then I'm up the creek.
    TIA
    Bob
    > If you have another and it's work the obvious answer is it's broken.
    > Likely breakage is grease turned to goo or no read.

    I have another 851 that I use as my A: drive and it works just fine. I
    have been testing the Drive as B:
    Bob

  5. Re: SEEK Errors on a SHUGART 851

    On Tue, 01 Jul 2008 07:49:28 -0500, "Robert J. Stevens"
    wrote:

    > If I Make sure the Heads are fully retracted it will keep displaying Track Zero Over and Over. Guess it doesn't check to see if it stepped.


    That sounds more like the track 00 sensor doesn't detect that it IS on
    track 00 ... usually, a 'seek' starts with a re-cal to track 00, then
    stepping out to track ...whatever ... The IR transmitters/receivers
    of that era weren't anywhere near as reliable they are now.

    Bill

  6. Re: SEEK Errors on a SHUGART 851

    Robert J. Stevens wrote:
    (snip)

    > I am using my CompuPro 816 with a DISK1A.I have a program DUF05 that
    > runs under CP/M 2.2 and it has an OPTION to display the Disk to the
    > screen. If I Make sure the Heads are fully retracted it will keep
    > displaying Track Zero Over and Over. Guess it doesn't check to see if it
    > stepped.


    > Trying to format a Disk gets a "Seek Error". I am trying to get a
    > schematic then I can check the IC that drives the stepper for failure.
    > If the Stepper itself has failed then I'm up the creek.


    Possibly the stepper power supply. I believe it is usual for
    8 inch drives to use 5V and 24V power, plus on many 115VAC for
    the drive motor. The 24V would seem to be for the stepper.
    Later drives also use 24V for the drive motor.

    -- glen


  7. Re: SEEK Errors on a SHUGART 851

    On Tue, 01 Jul 2008 07:49:28 -0500, "Robert J. Stevens"
    wrote:

    >no.spam@no.uce.bellatlantic.net wrote:
    >> On Fri, 27 Jun 2008 07:16:51 -0500, "Robert J. Stevens"
    >> wrote:
    >>
    >>> I have a Shugart 851 that is giving me SEEK Errors the Heads don't seem
    >>> to be stepping.
    >>> I also have an 850 that does the same thing
    >>> Does anyone have any Insight on this Problem.
    >>> I checked all the Jumpers, Trying it as B: [jumper set accordingly].
    >>> Also have a Terminator plugged in.
    >>> I know the connections are OK as I can swap in another drive and they
    >>> all work OK,
    >>> TIA
    >>> Bob in Wisconsin
    >>> USE
    >>> trebor72@execpc.com
    >>>

    >>
    >> Ok. what FDC is driving the Floppy? What is it doing when it reports
    >> a seek error? For example is it doing a recal (seek to 000)?
    >>

    >Allison;
    >I am using my CompuPro 816 with a DISK1A.I have a program DUF05 that runs under CP/M 2.2 and it has an OPTION to display the Disk to the screen. If I Make sure the Heads are fully retracted it will keep displaying Track Zero Over and Over. Guess it doesn't check to see if it stepped.
    >
    >Trying to format a Disk gets a "Seek Error". I am trying to get a
    >schematic then I can check the IC that drives the stepper for failure.
    >If the Stepper itself has failed then I'm up the creek.


    OK Seek error m,eans the FDC didn't see trackk 000 after stepping in
    or When the FDC read a track the Cylinder number on the track didn't
    match.

    I'd be surprized if the stepper were bad. I'd suspect first is the
    stepper drive getting power (internal to the board) and is the power
    being delivered to the stepper motor.

    It's easy to ohm out the motor. I'll bet there is a local fuse or
    fuseable resistor that "went away".

    Allison

    >TIA
    >Bob
    >> If you have another and it's work the obvious answer is it's broken.
    >> Likely breakage is grease turned to goo or no read.

    >I have another 851 that I use as my A: drive and it works just fine. I
    >have been testing the Drive as B:
    >Bob



  8. Re: SEEK Errors on a SHUGART 851

    On Tue, 01 Jul 2008 13:41:46 -0500, Bill
    wrote:

    >On Tue, 01 Jul 2008 07:49:28 -0500, "Robert J. Stevens"
    > wrote:
    >
    >> If I Make sure the Heads are fully retracted it will keep displaying Track Zero Over and Over. Guess it doesn't check to see if it stepped.

    >
    >That sounds more like the track 00 sensor doesn't detect that it IS on
    >track 00 ... usually, a 'seek' starts with a re-cal to track 00, then
    >stepping out to track ...whatever ... The IR transmitters/receivers
    >of that era weren't anywhere near as reliable they are now.


    That would be true at the software level but no tat the 765 level.
    The only time the FDC looks at track00 is during Recal command
    and it issued up to 77 steps and if there isn't a TRK00 then it's a
    seek fail. The other way to get a seek fail is step to any clinder
    and do a read and the cylinder number does not match the C
    value in the command.

    The Disk1A is 765 based.

    Allison

    >Bill



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