Telequipment D75 Scope

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

 

Is it a particular waveform from a specific signal, or is it a general problem you have with your scope?

 

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

 

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

 

Bertus,

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

Clive

 

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

 

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