"Dave" wrote in message
news:Jwo0i.39373$KN6.7185@edtnps89...

"Dave" wrote in message
news:jQH_h.10486$KN6.6932@edtnps89...
I'd like to know what the minimum useful bandwidth is for an oscilloscope
to be used for general TV and audio equipment troubleshooting and repair.
I've stumbled across a 20MHz dual-trace scope at a second-hand store, it
appears to work and they only want $50 for it. The brand is "Leader"
which I'm not familiar with. Comments?

When the scope is powered up, it has a white line which starts to cross
the screen from left to right. The line gets about halfway across, then
disappears and doesn't come back.

The trace sweeps from left to right and should be blanked on the return
stroke.

Does this mean the scope is disfunctional? I thought it should have a
steady horizontal line when it's turned on with no inputs.

If the trace only goes half way across the screen try centering it with the
horizontal shift control.