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ETX-125 Motor Unit Fault

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  • Mark
    Just bought an ETX-125EC (new version with ball bearings) on ebay. Would have been a fantastic deal if I hadn t got a Motor Unit Fault when I tried a calibrate
    Message 1 of 11 , Apr 1, 2010
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      Just bought an ETX-125EC (new version with ball bearings) on ebay. Would have been a fantastic deal if I hadn't got a Motor Unit Fault when I tried a calibrate motors...

      Tried it with two autostars that worked fine on my etx-90 and etx-80. Both are running the "gg firmware"

      - 497: On initial startup, no movement of scope (nor any motor sound) when I hit the arrow keys. Tried train, no movement. Then tried Calibrate and got MFU.
      - Plugged in a 495, got a MFU on calibrate, reset it, and now get the MFU on power on. I tried both internal and external power, no change...

      This sounds bad... Most of the MFU suggestions seem to center around power. However, I did not hear any motor sounds on either axis and I did try an external power supply.

      Suggestions on how I might debug this? Being a newer EC, there seems to be a general warning not to grab my toolkit and disassemble...

      Thanks!

      Mark
    • autostaretx
      ... No, that s a second 497. If it was still a 495 it would have refused to operate and said Use ETX Autostar with this scope on the screen. Once you ve
      Message 2 of 11 , Apr 2, 2010
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        --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@...> wrote:
        >
        > Just bought an ETX-125EC (new version with ball bearings) on ebay. Would have been a fantastic deal if I hadn't got a Motor Unit Fault when I tried a calibrate motors...
        >
        > Tried it with two autostars that worked fine on my etx-90 and etx-80. Both are running the "gg firmware"
        >
        > - 497: On initial startup, no movement of scope (nor any motor sound) when I hit the arrow keys. Tried train, no movement. Then tried Calibrate and got MFU.
        > - Plugged in a 495, got a MFU on calibrate, reset it, and now get the MFU on power on. I tried both internal and external power, no change...

        No, that's a second 497. If it was still a 495 it would have refused to operate and said "Use ETX Autostar with this scope" on the screen.
        Once you've loaded 497 firmware it -is- a 497, irrespective of its history. (i'm being strict to avoid confusion in future postings)


        > This sounds bad... Most of the MFU suggestions seem to center around power. However, I did not hear any motor sounds on either axis and I did try an external power supply.

        I strongly suspect that "power" has little to do with it.

        I'd vote for: (a) loose connector (remove bottom cover and look)
        (b) damaged wire between connector and motor card (same approach)
        (c) copper trace blown off either the power panel or motor card
        (open bottom, inspect... then try to determine -why- it blew
        (see next))
        (d) dead chip on motor card (usually one of the motor power FETs)
        (can cause (c))
        (e) bad motor (which can cause (c) and (d))

        >
        > Suggestions on how I might debug this? Being a newer EC, there seems to be a general warning not to grab my toolkit and disassemble...

        Opening the base is not a problem... the three(?) screws are either visible or hiding under the rubber feet.

        Take photos, draw annotated sketches and make overly complete notes BEFORE unplugging cables... an all-to-frequent posting is "i forget which way the plugs go" by poor note-takers.

        good luck
        --dick
      • pinyachta
        Barring a hole or melted pin connections is there a way to test for a bad MOSFET? TIA ... (can cause (c))
        Message 3 of 11 , Apr 2, 2010
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          Barring a hole or melted pin connections is there a way to test for a bad MOSFET? TIA

          --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@...> wrote:
          > (d) dead chip on motor card (usually one of the motor power FETs)
          (can cause (c))
        • autostaretx
          On an unpowered board, there should be no connection between the motor wires and the power/ground lines (that tests for a shorted segment). The following
          Message 4 of 11 , Apr 2, 2010
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            On an unpowered board, there should be no connection between the motor wires and the power/ground lines (that tests for a shorted segment).

            The following tests assume careful workmanship and proper probe setup so that you don't "slip" and cause more damage while testing:

            Then you measure a -lot- of combinations (multiple voltmeters help, and oscilloscope is even better): power to each motor lead, across motor, ground to each motor lead,
            all while trying to send slewing signals to the motor.
            Unfortunately you slightly shot yourself in the foot by Resetting the Autostar... one of the things a boot-after-reset does is a "Calibrate Motors", and you're hanging there.
            At least when the calibration is attempting to run the motor, you might see signals coming to (at least half of) the motor.

            The -first- question is: is -either- end of the motor being "driven"?
            ("driven" means that the leads (or even one) is being lifted to +12v or pulled to ground by the FET.). Are the gates of the FETs being driven?

            I've just created a "Schematics" folder in the files area.
            It has an example motor control card (derived from Meade's patents) to help guide you.
            http://tech.groups.yahoo.com/group/ETXASTRO/files/Schematics/

            good luck
            --dick

            --- In ETXASTRO@yahoogroups.com, "pinyachta" <pinyachta@...> wrote:
            >
            > Barring a hole or melted pin connections is there a way to test for a bad MOSFET? TIA
            >
            > --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@> wrote:
            > > (d) dead chip on motor card (usually one of the motor power FETs)
            > (can cause (c))
            >
          • Mark
            Yup, there was a loose connector on the board that controls the azimuth axis. Got one axis working, the other still fails. But... Apparently the original cause
            Message 5 of 11 , Apr 2, 2010
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              Yup, there was a loose connector on the board that controls the azimuth axis. Got one axis working, the other still fails.

              But...

              Apparently the original cause was that the piece of the gear box that held the shaft of the long gear in place (basically a plastic bearing run), split, and the piece still attached to shaft of the large diameter gear shaft swung around and caught the wire harness and flipped it off.

              So now I got two problems:
              1. Still motor fault on the altitude axis
              2. A split bearing on the azimuth axis gear box.

              I assume the tact I should take on #1 is to switch the wires between the two axis and see if the failure moves with the wires (i.e. motor/driver failure) or is the position on the power board.

              In regards to the bearing repair, I suspect it is not as simple as just gluing the broken plastic pieces together. Am I right?

              Thanks for the help and encouragement!

              Mark

              --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@...> wrote:
              >
              >
              >
              > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
              > >
              > > Just bought an ETX-125EC (new version with ball bearings) on ebay. Would have been a fantastic deal if I hadn't got a Motor Unit Fault when I tried a calibrate motors...
              > >
              > > Tried it with two autostars that worked fine on my etx-90 and etx-80. Both are running the "gg firmware"
              > >
              > > - 497: On initial startup, no movement of scope (nor any motor sound) when I hit the arrow keys. Tried train, no movement. Then tried Calibrate and got MFU.
              > > - Plugged in a 495, got a MFU on calibrate, reset it, and now get the MFU on power on. I tried both internal and external power, no change...
              >
              > No, that's a second 497. If it was still a 495 it would have refused to operate and said "Use ETX Autostar with this scope" on the screen.
              > Once you've loaded 497 firmware it -is- a 497, irrespective of its history. (i'm being strict to avoid confusion in future postings)
              >
              >
              > > This sounds bad... Most of the MFU suggestions seem to center around power. However, I did not hear any motor sounds on either axis and I did try an external power supply.
              >
              > I strongly suspect that "power" has little to do with it.
              >
              > I'd vote for: (a) loose connector (remove bottom cover and look)
              > (b) damaged wire between connector and motor card (same approach)
              > (c) copper trace blown off either the power panel or motor card
              > (open bottom, inspect... then try to determine -why- it blew
              > (see next))
              > (d) dead chip on motor card (usually one of the motor power FETs)
              > (can cause (c))
              > (e) bad motor (which can cause (c) and (d))
              >
              > >
              > > Suggestions on how I might debug this? Being a newer EC, there seems to be a general warning not to grab my toolkit and disassemble...
              >
              > Opening the base is not a problem... the three(?) screws are either visible or hiding under the rubber feet.
              >
              > Take photos, draw annotated sketches and make overly complete notes BEFORE unplugging cables... an all-to-frequent posting is "i forget which way the plugs go" by poor note-takers.
              >
              > good luck
              > --dick
              >
            • autostaretx
              ... Yes... that s the correct approach. If it works in the other position, it s either an autostar issue, (but your two autostars experience says not that )
              Message 6 of 11 , Apr 3, 2010
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                --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@...> wrote:
                >
                > Yup, there was a loose connector on the board that controls the azimuth axis. Got one axis working, the other still fails.
                >
                > But...
                >
                > Apparently the original cause was that the piece of the gear box that held the shaft of the long gear in place (basically a plastic bearing run), split, and the piece still attached to shaft of the large diameter gear shaft swung around and caught the wire harness and flipped it off.
                >
                > So now I got two problems:
                > 1. Still motor fault on the altitude axis
                > 2. A split bearing on the azimuth axis gear box.
                >
                > I assume the tact I should take on #1 is to switch the wires
                > between the two axis and see if the failure moves with the wires
                > (i.e. motor/driver failure) or is the position on the power board.

                Yes... that's the correct approach.
                If it works in the other position, it's either an autostar issue, (but your "two autostars" experience says "not that") or a hidden trace has been blown off the board.

                > In regards to the bearing repair, I suspect it is not as simple as
                > just gluing the broken plastic pieces together. Am I right?

                For some folks, "just gluing" has worked.
                Usually they add reinforcement of some sort.
                Mike Weasner's site http://www.weasner.com/etx has dozens of
                postings (linked from his Tech Info page) showing similar work.

                > Thanks for the help and encouragement!

                good luck
                --dick

                >
                > Mark
                >
                > --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@> wrote:
                > >
                > >
                > >
                > > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
                > > >
                > > > Just bought an ETX-125EC (new version with ball bearings) on ebay. Would have been a fantastic deal if I hadn't got a Motor Unit Fault when I tried a calibrate motors...
                > > >
                > > > Tried it with two autostars that worked fine on my etx-90 and etx-80. Both are running the "gg firmware"
                > > >
                > > > - 497: On initial startup, no movement of scope (nor any motor sound) when I hit the arrow keys. Tried train, no movement. Then tried Calibrate and got MFU.
                > > > - Plugged in a 495, got a MFU on calibrate, reset it, and now get the MFU on power on. I tried both internal and external power, no change...
                > >
                > > No, that's a second 497. If it was still a 495 it would have refused to operate and said "Use ETX Autostar with this scope" on the screen.
                > > Once you've loaded 497 firmware it -is- a 497, irrespective of its history. (i'm being strict to avoid confusion in future postings)
                > >
                > >
                > > > This sounds bad... Most of the MFU suggestions seem to center around power. However, I did not hear any motor sounds on either axis and I did try an external power supply.
                > >
                > > I strongly suspect that "power" has little to do with it.
                > >
                > > I'd vote for: (a) loose connector (remove bottom cover and look)
                > > (b) damaged wire between connector and motor card (same approach)
                > > (c) copper trace blown off either the power panel or motor card
                > > (open bottom, inspect... then try to determine -why- it blew
                > > (see next))
                > > (d) dead chip on motor card (usually one of the motor power FETs)
                > > (can cause (c))
                > > (e) bad motor (which can cause (c) and (d))
                > >
                > > >
                > > > Suggestions on how I might debug this? Being a newer EC, there seems to be a general warning not to grab my toolkit and disassemble...
                > >
                > > Opening the base is not a problem... the three(?) screws are either visible or hiding under the rubber feet.
                > >
                > > Take photos, draw annotated sketches and make overly complete notes BEFORE unplugging cables... an all-to-frequent posting is "i forget which way the plugs go" by poor note-takers.
                > >
                > > good luck
                > > --dick
                > >
                >
              • Mark
                So the problem followed the axis, not the position. So I have a problem with the altitude axis. I unplugged the cable to the altitude axis, and compared all
                Message 7 of 11 , Apr 3, 2010
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                  So the problem followed the axis, not the position. So I have a problem with the altitude axis.

                  I unplugged the cable to the altitude axis, and compared all the wires to each other and then to ground (I used the central clutch system as my ground.) - No power anywhere.

                  I got a short to ground on the red wire (I think that is the data wire for the axis?) Is that normal?

                  Thanks!

                  Mark

                  --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@...> wrote:
                  >
                  > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
                  > >
                  > > Yup, there was a loose connector on the board that controls the azimuth axis. Got one axis working, the other still fails.
                  > >
                  > > But...
                  > >
                  > > Apparently the original cause was that the piece of the gear box that held the shaft of the long gear in place (basically a plastic bearing run), split, and the piece still attached to shaft of the large diameter gear shaft swung around and caught the wire harness and flipped it off.
                  > >
                  > > So now I got two problems:
                  > > 1. Still motor fault on the altitude axis
                  > > 2. A split bearing on the azimuth axis gear box.
                  > >
                  > > I assume the tact I should take on #1 is to switch the wires
                  > > between the two axis and see if the failure moves with the wires
                  > > (i.e. motor/driver failure) or is the position on the power board.
                  >
                  > Yes... that's the correct approach.
                  > If it works in the other position, it's either an autostar issue, (but your "two autostars" experience says "not that") or a hidden trace has been blown off the board.
                  >
                  > > In regards to the bearing repair, I suspect it is not as simple as
                  > > just gluing the broken plastic pieces together. Am I right?
                  >
                  > For some folks, "just gluing" has worked.
                  > Usually they add reinforcement of some sort.
                  > Mike Weasner's site http://www.weasner.com/etx has dozens of
                  > postings (linked from his Tech Info page) showing similar work.
                  >
                  > > Thanks for the help and encouragement!
                  >
                  > good luck
                  > --dick
                  >
                  > >
                  > > Mark
                  > >
                  > > --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@> wrote:
                  > > >
                  > > >
                  > > >
                  > > > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
                  > > > >
                  > > > > Just bought an ETX-125EC (new version with ball bearings) on ebay. Would have been a fantastic deal if I hadn't got a Motor Unit Fault when I tried a calibrate motors...
                  > > > >
                  > > > > Tried it with two autostars that worked fine on my etx-90 and etx-80. Both are running the "gg firmware"
                  > > > >
                  > > > > - 497: On initial startup, no movement of scope (nor any motor sound) when I hit the arrow keys. Tried train, no movement. Then tried Calibrate and got MFU.
                  > > > > - Plugged in a 495, got a MFU on calibrate, reset it, and now get the MFU on power on. I tried both internal and external power, no change...
                  > > >
                  > > > No, that's a second 497. If it was still a 495 it would have refused to operate and said "Use ETX Autostar with this scope" on the screen.
                  > > > Once you've loaded 497 firmware it -is- a 497, irrespective of its history. (i'm being strict to avoid confusion in future postings)
                  > > >
                  > > >
                  > > > > This sounds bad... Most of the MFU suggestions seem to center around power. However, I did not hear any motor sounds on either axis and I did try an external power supply.
                  > > >
                  > > > I strongly suspect that "power" has little to do with it.
                  > > >
                  > > > I'd vote for: (a) loose connector (remove bottom cover and look)
                  > > > (b) damaged wire between connector and motor card (same approach)
                  > > > (c) copper trace blown off either the power panel or motor card
                  > > > (open bottom, inspect... then try to determine -why- it blew
                  > > > (see next))
                  > > > (d) dead chip on motor card (usually one of the motor power FETs)
                  > > > (can cause (c))
                  > > > (e) bad motor (which can cause (c) and (d))
                  > > >
                  > > > >
                  > > > > Suggestions on how I might debug this? Being a newer EC, there seems to be a general warning not to grab my toolkit and disassemble...
                  > > >
                  > > > Opening the base is not a problem... the three(?) screws are either visible or hiding under the rubber feet.
                  > > >
                  > > > Take photos, draw annotated sketches and make overly complete notes BEFORE unplugging cables... an all-to-frequent posting is "i forget which way the plugs go" by poor note-takers.
                  > > >
                  > > > good luck
                  > > > --dick
                  > > >
                  > >
                  >
                • autostaretx
                  Meade s internal wire colors are not necessarily the same as the rest of the world s (-outside- of Meade, i d expect red to be +12, black to be ground, and
                  Message 8 of 11 , Apr 3, 2010
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                    Meade's internal wire colors are not necessarily the same as the rest of the world's (-outside- of Meade, i'd expect red to be +12, black to be ground, and other colors to be signal... but INSIDE a Meade, that is not always (if ever) their conventional usage)

                    To determine which wire does what, you have to -look- at the board and determine who does what. For example, the Ground is going to go to the negative lead of the electrolytic filter capacitor.
                    +12v is going to go to the "input" pin of the 5v regulator.

                    As for the "short to ground", it's not clear from your description which ground you're comparing the red wire to.
                    You could attach the Alt cable at the power panel end, and unplug it from the motor card... does red now short to the AZ motor's ground?
                    If so, then red (in that cable) is probably simply "ground".

                    good luck
                    --dick

                    --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@...> wrote:
                    >
                    > So the problem followed the axis, not the position. So I have a problem with the altitude axis.
                    >
                    > I unplugged the cable to the altitude axis, and compared all the wires to each other and then to ground (I used the central clutch system as my ground.) - No power anywhere.
                    >
                    > I got a short to ground on the red wire (I think that is the data wire for the axis?) Is that normal?
                    >
                    > Thanks!
                    >
                    > Mark
                    >
                    > --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@> wrote:
                    > >
                    > > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
                    > > >
                    > > > Yup, there was a loose connector on the board that controls the azimuth axis. Got one axis working, the other still fails.
                    > > >
                    > > > But...
                    > > >
                    > > > Apparently the original cause was that the piece of the gear box that held the shaft of the long gear in place (basically a plastic bearing run), split, and the piece still attached to shaft of the large diameter gear shaft swung around and caught the wire harness and flipped it off.
                    > > >
                    > > > So now I got two problems:
                    > > > 1. Still motor fault on the altitude axis
                    > > > 2. A split bearing on the azimuth axis gear box.
                    > > >
                    > > > I assume the tact I should take on #1 is to switch the wires
                    > > > between the two axis and see if the failure moves with the wires
                    > > > (i.e. motor/driver failure) or is the position on the power board.
                    > >
                    > > Yes... that's the correct approach.
                    > > If it works in the other position, it's either an autostar issue, (but your "two autostars" experience says "not that") or a hidden trace has been blown off the board.
                    > >
                    > > > In regards to the bearing repair, I suspect it is not as simple as
                    > > > just gluing the broken plastic pieces together. Am I right?
                    > >
                    > > For some folks, "just gluing" has worked.
                    > > Usually they add reinforcement of some sort.
                    > > Mike Weasner's site http://www.weasner.com/etx has dozens of
                    > > postings (linked from his Tech Info page) showing similar work.
                    > >
                    > > > Thanks for the help and encouragement!
                    > >
                    > > good luck
                    > > --dick
                    > >
                    > > >
                    > > > Mark
                    > > >
                    > > > --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@> wrote:
                    > > > >
                    > > > >
                    > > > >
                    > > > > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
                    > > > > >
                    > > > > > Just bought an ETX-125EC (new version with ball bearings) on ebay. Would have been a fantastic deal if I hadn't got a Motor Unit Fault when I tried a calibrate motors...
                    > > > > >
                    > > > > > Tried it with two autostars that worked fine on my etx-90 and etx-80. Both are running the "gg firmware"
                    > > > > >
                    > > > > > - 497: On initial startup, no movement of scope (nor any motor sound) when I hit the arrow keys. Tried train, no movement. Then tried Calibrate and got MFU.
                    > > > > > - Plugged in a 495, got a MFU on calibrate, reset it, and now get the MFU on power on. I tried both internal and external power, no change...
                    > > > >
                    > > > > No, that's a second 497. If it was still a 495 it would have refused to operate and said "Use ETX Autostar with this scope" on the screen.
                    > > > > Once you've loaded 497 firmware it -is- a 497, irrespective of its history. (i'm being strict to avoid confusion in future postings)
                    > > > >
                    > > > >
                    > > > > > This sounds bad... Most of the MFU suggestions seem to center around power. However, I did not hear any motor sounds on either axis and I did try an external power supply.
                    > > > >
                    > > > > I strongly suspect that "power" has little to do with it.
                    > > > >
                    > > > > I'd vote for: (a) loose connector (remove bottom cover and look)
                    > > > > (b) damaged wire between connector and motor card (same approach)
                    > > > > (c) copper trace blown off either the power panel or motor card
                    > > > > (open bottom, inspect... then try to determine -why- it blew
                    > > > > (see next))
                    > > > > (d) dead chip on motor card (usually one of the motor power FETs)
                    > > > > (can cause (c))
                    > > > > (e) bad motor (which can cause (c) and (d))
                    > > > >
                    > > > > >
                    > > > > > Suggestions on how I might debug this? Being a newer EC, there seems to be a general warning not to grab my toolkit and disassemble...
                    > > > >
                    > > > > Opening the base is not a problem... the three(?) screws are either visible or hiding under the rubber feet.
                    > > > >
                    > > > > Take photos, draw annotated sketches and make overly complete notes BEFORE unplugging cables... an all-to-frequent posting is "i forget which way the plugs go" by poor note-takers.
                    > > > >
                    > > > > good luck
                    > > > > --dick
                    > > > >
                    > > >
                    > >
                    >
                  • pinyachta
                    ... Power is fed from the power panel to the alt. motor control bd. by the BLACK wire, RED is ground. You should have 12v+/- between the 1 and 4 Alt pins on
                    Message 9 of 11 , Apr 3, 2010
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                      --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@...> wrote:
                      >
                      > So the problem followed the axis, not the position. So I have a problem with the altitude axis.
                      >
                      > I unplugged the cable to the altitude axis, and compared all the wires to each other and then to ground (I used the central clutch system as my ground.) - No power anywhere.
                      >
                      > I got a short to ground on the red wire (I think that is the data wire for the axis?) Is that normal?
                      >

                      Power is fed from the power panel to the alt. motor control bd. by the BLACK wire, RED is ground. You should have 12v+/- between the 1 and 4 Alt pins on the power panel.

                      The Blue and Yellow are connected to pins 17 & 18 of the PIC16C54. Pins 17 and 18 are bi-directional I/O ports. I added another motor control board schema to dick's file with some corrections. The pinouts to the PIC are incorrect there are only 18 pins on the 16C54. The JP2 pin calls are wrong too. I'm not sure whether blue is the clock or data connection so I didn't indicate their function. I redrew the wiring to match the physical layout of JP2.

                      The good news is that I have a alt drive that should work. I also have one undamaged RA gear box. Let me know if you need them.

                      Geo.
                    • Mark
                      Hi, Finally got to the bottom of things. The wire that goes through the bolt that tightens the RA axis and snakes it way up to the fork arm was cut. Somebody
                      Message 10 of 11 , Apr 4, 2010
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                        Hi,

                        Finally got to the bottom of things. The wire that goes through the bolt that tightens the RA axis and snakes it way up to the fork arm was cut. Somebody (perhaps me) loosened the bolt and cut the wires.

                        Re-wired it and plugged it in and I now have both Dec and RA drives!

                        To recap the bidding...

                        1. The RA axis died because the brace for the worm gear coming off the gear box broke and pulled the power off.

                        2. The Dec axis died because the wires going up through the bolt that locks the RA axis was cut.

                        Now I just got to re-assemble....

                        Thanks to all for help!

                        Mark

                        --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@...> wrote:
                        >
                        > So the problem followed the axis, not the position. So I have a problem with the altitude axis.
                        >
                        > I unplugged the cable to the altitude axis, and compared all the wires to each other and then to ground (I used the central clutch system as my ground.) - No power anywhere.
                        >
                        > I got a short to ground on the red wire (I think that is the data wire for the axis?) Is that normal?
                        >
                        > Thanks!
                        >
                        > Mark
                        >
                        > --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@> wrote:
                        > >
                        > > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
                        > > >
                        > > > Yup, there was a loose connector on the board that controls the azimuth axis. Got one axis working, the other still fails.
                        > > >
                        > > > But...
                        > > >
                        > > > Apparently the original cause was that the piece of the gear box that held the shaft of the long gear in place (basically a plastic bearing run), split, and the piece still attached to shaft of the large diameter gear shaft swung around and caught the wire harness and flipped it off.
                        > > >
                        > > > So now I got two problems:
                        > > > 1. Still motor fault on the altitude axis
                        > > > 2. A split bearing on the azimuth axis gear box.
                        > > >
                        > > > I assume the tact I should take on #1 is to switch the wires
                        > > > between the two axis and see if the failure moves with the wires
                        > > > (i.e. motor/driver failure) or is the position on the power board.
                        > >
                        > > Yes... that's the correct approach.
                        > > If it works in the other position, it's either an autostar issue, (but your "two autostars" experience says "not that") or a hidden trace has been blown off the board.
                        > >
                        > > > In regards to the bearing repair, I suspect it is not as simple as
                        > > > just gluing the broken plastic pieces together. Am I right?
                        > >
                        > > For some folks, "just gluing" has worked.
                        > > Usually they add reinforcement of some sort.
                        > > Mike Weasner's site http://www.weasner.com/etx has dozens of
                        > > postings (linked from his Tech Info page) showing similar work.
                        > >
                        > > > Thanks for the help and encouragement!
                        > >
                        > > good luck
                        > > --dick
                        > >
                        > > >
                        > > > Mark
                        > > >
                        > > > --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@> wrote:
                        > > > >
                        > > > >
                        > > > >
                        > > > > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
                        > > > > >
                        > > > > > Just bought an ETX-125EC (new version with ball bearings) on ebay. Would have been a fantastic deal if I hadn't got a Motor Unit Fault when I tried a calibrate motors...
                        > > > > >
                        > > > > > Tried it with two autostars that worked fine on my etx-90 and etx-80. Both are running the "gg firmware"
                        > > > > >
                        > > > > > - 497: On initial startup, no movement of scope (nor any motor sound) when I hit the arrow keys. Tried train, no movement. Then tried Calibrate and got MFU.
                        > > > > > - Plugged in a 495, got a MFU on calibrate, reset it, and now get the MFU on power on. I tried both internal and external power, no change...
                        > > > >
                        > > > > No, that's a second 497. If it was still a 495 it would have refused to operate and said "Use ETX Autostar with this scope" on the screen.
                        > > > > Once you've loaded 497 firmware it -is- a 497, irrespective of its history. (i'm being strict to avoid confusion in future postings)
                        > > > >
                        > > > >
                        > > > > > This sounds bad... Most of the MFU suggestions seem to center around power. However, I did not hear any motor sounds on either axis and I did try an external power supply.
                        > > > >
                        > > > > I strongly suspect that "power" has little to do with it.
                        > > > >
                        > > > > I'd vote for: (a) loose connector (remove bottom cover and look)
                        > > > > (b) damaged wire between connector and motor card (same approach)
                        > > > > (c) copper trace blown off either the power panel or motor card
                        > > > > (open bottom, inspect... then try to determine -why- it blew
                        > > > > (see next))
                        > > > > (d) dead chip on motor card (usually one of the motor power FETs)
                        > > > > (can cause (c))
                        > > > > (e) bad motor (which can cause (c) and (d))
                        > > > >
                        > > > > >
                        > > > > > Suggestions on how I might debug this? Being a newer EC, there seems to be a general warning not to grab my toolkit and disassemble...
                        > > > >
                        > > > > Opening the base is not a problem... the three(?) screws are either visible or hiding under the rubber feet.
                        > > > >
                        > > > > Take photos, draw annotated sketches and make overly complete notes BEFORE unplugging cables... an all-to-frequent posting is "i forget which way the plugs go" by poor note-takers.
                        > > > >
                        > > > > good luck
                        > > > > --dick
                        > > > >
                        > > >
                        > >
                        >
                      • Mark
                        I am operational again! Thank you all! Mark
                        Message 11 of 11 , Apr 17, 2010
                        • 0 Attachment
                          I am operational again! Thank you all!

                          Mark

                          --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@...> wrote:
                          >
                          > Hi,
                          >
                          > Finally got to the bottom of things. The wire that goes through the bolt that tightens the RA axis and snakes it way up to the fork arm was cut. Somebody (perhaps me) loosened the bolt and cut the wires.
                          >
                          > Re-wired it and plugged it in and I now have both Dec and RA drives!
                          >
                          > To recap the bidding...
                          >
                          > 1. The RA axis died because the brace for the worm gear coming off the gear box broke and pulled the power off.
                          >
                          > 2. The Dec axis died because the wires going up through the bolt that locks the RA axis was cut.
                          >
                          > Now I just got to re-assemble....
                          >
                          > Thanks to all for help!
                          >
                          > Mark
                          >
                          > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
                          > >
                          > > So the problem followed the axis, not the position. So I have a problem with the altitude axis.
                          > >
                          > > I unplugged the cable to the altitude axis, and compared all the wires to each other and then to ground (I used the central clutch system as my ground.) - No power anywhere.
                          > >
                          > > I got a short to ground on the red wire (I think that is the data wire for the axis?) Is that normal?
                          > >
                          > > Thanks!
                          > >
                          > > Mark
                          > >
                          > > --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@> wrote:
                          > > >
                          > > > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
                          > > > >
                          > > > > Yup, there was a loose connector on the board that controls the azimuth axis. Got one axis working, the other still fails.
                          > > > >
                          > > > > But...
                          > > > >
                          > > > > Apparently the original cause was that the piece of the gear box that held the shaft of the long gear in place (basically a plastic bearing run), split, and the piece still attached to shaft of the large diameter gear shaft swung around and caught the wire harness and flipped it off.
                          > > > >
                          > > > > So now I got two problems:
                          > > > > 1. Still motor fault on the altitude axis
                          > > > > 2. A split bearing on the azimuth axis gear box.
                          > > > >
                          > > > > I assume the tact I should take on #1 is to switch the wires
                          > > > > between the two axis and see if the failure moves with the wires
                          > > > > (i.e. motor/driver failure) or is the position on the power board.
                          > > >
                          > > > Yes... that's the correct approach.
                          > > > If it works in the other position, it's either an autostar issue, (but your "two autostars" experience says "not that") or a hidden trace has been blown off the board.
                          > > >
                          > > > > In regards to the bearing repair, I suspect it is not as simple as
                          > > > > just gluing the broken plastic pieces together. Am I right?
                          > > >
                          > > > For some folks, "just gluing" has worked.
                          > > > Usually they add reinforcement of some sort.
                          > > > Mike Weasner's site http://www.weasner.com/etx has dozens of
                          > > > postings (linked from his Tech Info page) showing similar work.
                          > > >
                          > > > > Thanks for the help and encouragement!
                          > > >
                          > > > good luck
                          > > > --dick
                          > > >
                          > > > >
                          > > > > Mark
                          > > > >
                          > > > > --- In ETXASTRO@yahoogroups.com, "autostaretx" <rseymour@> wrote:
                          > > > > >
                          > > > > >
                          > > > > >
                          > > > > > --- In ETXASTRO@yahoogroups.com, "Mark" <mark2382@> wrote:
                          > > > > > >
                          > > > > > > Just bought an ETX-125EC (new version with ball bearings) on ebay. Would have been a fantastic deal if I hadn't got a Motor Unit Fault when I tried a calibrate motors...
                          > > > > > >
                          > > > > > > Tried it with two autostars that worked fine on my etx-90 and etx-80. Both are running the "gg firmware"
                          > > > > > >
                          > > > > > > - 497: On initial startup, no movement of scope (nor any motor sound) when I hit the arrow keys. Tried train, no movement. Then tried Calibrate and got MFU.
                          > > > > > > - Plugged in a 495, got a MFU on calibrate, reset it, and now get the MFU on power on. I tried both internal and external power, no change...
                          > > > > >
                          > > > > > No, that's a second 497. If it was still a 495 it would have refused to operate and said "Use ETX Autostar with this scope" on the screen.
                          > > > > > Once you've loaded 497 firmware it -is- a 497, irrespective of its history. (i'm being strict to avoid confusion in future postings)
                          > > > > >
                          > > > > >
                          > > > > > > This sounds bad... Most of the MFU suggestions seem to center around power. However, I did not hear any motor sounds on either axis and I did try an external power supply.
                          > > > > >
                          > > > > > I strongly suspect that "power" has little to do with it.
                          > > > > >
                          > > > > > I'd vote for: (a) loose connector (remove bottom cover and look)
                          > > > > > (b) damaged wire between connector and motor card (same approach)
                          > > > > > (c) copper trace blown off either the power panel or motor card
                          > > > > > (open bottom, inspect... then try to determine -why- it blew
                          > > > > > (see next))
                          > > > > > (d) dead chip on motor card (usually one of the motor power FETs)
                          > > > > > (can cause (c))
                          > > > > > (e) bad motor (which can cause (c) and (d))
                          > > > > >
                          > > > > > >
                          > > > > > > Suggestions on how I might debug this? Being a newer EC, there seems to be a general warning not to grab my toolkit and disassemble...
                          > > > > >
                          > > > > > Opening the base is not a problem... the three(?) screws are either visible or hiding under the rubber feet.
                          > > > > >
                          > > > > > Take photos, draw annotated sketches and make overly complete notes BEFORE unplugging cables... an all-to-frequent posting is "i forget which way the plugs go" by poor note-takers.
                          > > > > >
                          > > > > > good luck
                          > > > > > --dick
                          > > > > >
                          > > > >
                          > > >
                          > >
                          >
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