Telequipment D75 Scope

Discussion in 'General Electronics Chat' started by Hoppy, Sep 9, 2010.

  1. Hoppy

    Thread Starter New Member

    Sep 9, 2010
    6
    0
    I have difficulty displaying a waveform and when displayed it disappears after a period of time. Can anyone please shed any light on the cause of this and how I can fix it. I have a service manual for this scope.

    Clive
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,646
    2,345
  3. hspalm

    Active Member

    Feb 17, 2010
    201
    8
    Is it a particular waveform from a specific signal, or is it a general problem you have with your scope?
     
  4. Hoppy

    Thread Starter New Member

    Sep 9, 2010
    6
    0
    Hello Bertus,

    Yes, it is unstable as it will display for a short time then disappear irrespective of how I adjust the level control.

    Clive
     
  5. Hoppy

    Thread Starter New Member

    Sep 9, 2010
    6
    0
    Its a general problem that has gradually got worse over a long period of time. I have to keep switching the timebase until I recover the trace.

    Clive

     
  6. bertus

    Administrator

    Apr 5, 2008
    15,646
    2,345
    Hello,

    Is the trigger AC or DC coupled?
    Is the trigger with or without RF reject?

    What kind of signal are you trying to measure?

    Bertus
     
  7. Hoppy

    Thread Starter New Member

    Sep 9, 2010
    6
    0
    Bertus,

    The problem is with a signal DC or AC coupled with or without RF reject and any waveform.

    Clive
     
  8. Hoppy

    Thread Starter New Member

    Sep 9, 2010
    6
    0
    I've now cleared the fault by stripping down the dual sweep plug-in module and replacing all electrolytic caps plus cleaning up the wafer switches on the timebase control. All transistors and diodes were also tested. Prior to clearing the fault I had also replaced all power supply caps and rail calibration pots, plus 6 KV EHT diodes with 10kV diodes.

    Most of the PCB's are reasonably accessible except in the amplifier and dual sweep plug-in modules which take time and patience to dismantle.

    Clive
     
  9. bertus

    Administrator

    Apr 5, 2008
    15,646
    2,345
    Hllo,

    Good to hear you got it working again.
    Contacts and capacitors can be a hard time to trace.
    I hope the calibration is still OK for you.

    Bertus
     
  10. Hoppy

    Thread Starter New Member

    Sep 9, 2010
    6
    0
    Hi Bertus,

    I have not completely re-calibrated the scope just reset the power rail voltages and adjusted front panel calibration pots. I don't use this scope for accurate measurements and mainly use it for general observation of complex waveforms.

    Regards
    Clive

     
Loading...