Tenma 72-6820 (Instek GOS-6112) Analogue CRO display issue.

[60fabfil]

Hi all, can someone help me with this issue? The scope is a Tenma 72-6820 (Instek GOS-6112).
Seems when any info display is showing on screen, the trace corrupts (dotty) like an interlacing effect, when the display is removed
and only the trace showing, it looks fine.
Sort of hard to explain, so I have attached link with Video. Moving the camera side to side highlights the effect.
Appreciate the help. thanks.

http://www.filedropper.com/tenma72-6820

[Chris56000]

Hi!

That looks like clock/timing signals from the readout generator circuitry is getting into the storage and/or
triggering circuitry when the readout circuits are in use, and the first thing I'd be thinking of is faulty supply decoupling!

I'll dig out my copy of the GOS6112 diagrams and get back with advice after I've studied them!

Chris Williams