Technics synthetiser SX-AX7 troubleshooting

Discussion in 'General Electronics Chat' started by nbern077, Feb 9, 2014.

  1. nbern077

    Thread Starter New Member

    Mar 17, 2012
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    Hi,

    I have a Technics synthetiser SX-AX7 (early 1990) I need to troubleshoot. I would benefit greatly from anybody having some experience with this equipement.

    Current status the equipement turn on correctly but all functions, lights seems frozen.

    I have scope power supply, signal and so far nothing abnormal, any ideas?

    Normand
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    got a schematic?
     
  3. nbern077

    Thread Starter New Member

    Mar 17, 2012
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    Yes I have the full manual
     
  4. nbern077

    Thread Starter New Member

    Mar 17, 2012
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    I am scanning the bloc diagram of the Synth.
     
  5. nbern077

    Thread Starter New Member

    Mar 17, 2012
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    Hi here is the bloc diagram of the equipment
     
  6. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    I would start by checking the power supply voltages, then check the reset lines for the dsp and aux cpu, and their clock sources. Also check the voltages on the ram and rom chips.
     
  7. nbern077

    Thread Starter New Member

    Mar 17, 2012
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    Here is the main board schematic

    Tx for your help
     
  8. nbern077

    Thread Starter New Member

    Mar 17, 2012
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    Power supply are good: 4.8, 4.9 instead of 5v, 14.1 instead of 15V, -15.01 instead of 15V
    All 4 Cristals are operating

    I will check the reset lines for the dsp and aux cpu.
     
  9. nbern077

    Thread Starter New Member

    Mar 17, 2012
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    No visible activity on the reset line.
     
  10. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Ok, but is the line high?
     
  11. nbern077

    Thread Starter New Member

    Mar 17, 2012
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    yes the line is at +5V
     
  12. nbern077

    Thread Starter New Member

    Mar 17, 2012
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    +5 for the CPU
    0 for gate array and the aux cpu
     
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