Telequipment D75 Scope

Thread Starter

Hoppy

Joined Sep 9, 2010
6
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
 

Thread Starter

Hoppy

Joined Sep 9, 2010
6
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
 

Thread Starter

Hoppy

Joined Sep 9, 2010
6
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

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

bertus

Joined Apr 5, 2008
20,108
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
 

Thread Starter

Hoppy

Joined Sep 9, 2010
6
Bertus,

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

Clive
 

Thread Starter

Hoppy

Joined Sep 9, 2010
6
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
 

bertus

Joined Apr 5, 2008
20,108
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
 

Thread Starter

Hoppy

Joined Sep 9, 2010
6
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

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
 
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