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Martin MX-4 scanner issue

Discussion in 'Troubleshooting and Repair' started by partyanimallighting, Feb 2, 2018.

  1. partyanimallighting

    partyanimallighting

    278
    2
    Oct 22, 2012
    Hi wizards, I need a little feedback on an issue I'm having with a Martin MX-4 scanner. I acquired four of these very old discontinued units (Circa 1999) and each one had issues that I have resolved after troubleshooting them one by one. The major issue I've encountered was malfunctioning TILT motors caused by faulty drivers but I resolved this by removing the old ULN2803A drivers and installing new drivers on new IC sockets. If the problem re-occurs, it'll be a simple swap out in the future. One unit however, has me baffled. I've gotten functional PAN, TILT, COLOR and GOBO but the SHUTTER continues to act erratically. So far I've done the following:
    1. Replaced all ULN2803A drivers
    2. Removed the SHUTTER motor, opened it up and checked but there are no visible problems.
    3. Swapped out the SHUTTER motor with the COLOR motor (all the motors carry the came number) and the COLOR functioned fine and the SHUTTER problem continued.
    4. Checked all six leads on the SHUTTER motor wire harness for continuity. All fine.
    5. Checked all solder traces on the PCB for continuity from the motor terminals to the ULN2803A drivers, then from the drivers to the ATMEL AT90S8515 microprocessor and all the traces are fine.
    Having done all this, all that's left for me is to assume that the microprocessor is faulty so I'll have to source a new (secondhand) PCB. Hence I'm throwing this out there for you gurus to take a look at before I commit to trying to replace the PCB.

    Any feedback will be greatly appreciated.

    Party Animal!! Martin MX-1 PCB 004.JPG Martin MX-4 Schematic.jpg PCB Terminal Layout.JPG
     
  2. partyanimallighting

    partyanimallighting

    278
    2
    Oct 22, 2012
    Hellooooo? Any feedback at all would be appreciated......Any........At all.
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,178
    2,690
    Jan 21, 2010
    Presumably you've traced the shutter control back to a pin on the microcontroller.

    There is a small, but finite probability that this lead of the microcontroller either wasn't soldered, or the solder joint had fractured.
     
  4. kellys_eye

    kellys_eye

    4,284
    1,145
    Jun 25, 2010
    Change C116 (10μf) - decoupling straight across the μP power lines. Could be transients causing it.
     
  5. partyanimallighting

    partyanimallighting

    278
    2
    Oct 22, 2012
    Hi (*steve*), I traced the lead from the shutter control from the harness pins back to the ULN2803A driver pins with the driver installed in the IC socket from the top of the driver pins with good continuity. The same goes with the leads from the driver back to the microcontroller. Good continuity there also. kellys_eye, I changed the C116 and this didn't resolve the issue either. Microcontroller issue??:confused:
     
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