Tektronix 2235A Vertical Trace Dim

[Shweaty]

Hey, y'all I've got an old Tek 2235A CRT scope. The trace is very dim only when it is dead vertical. If it's tracing any form of slope the entire trace is bright and in focus. If tracing a square wave though only the top and bottom portions of the wave in the X axis will be bright. The vertical portions (Y axis) of a square wave will be very dim. Any thoughts?




Thanks

[Krankshaft]

Re: Tektronix 2235A Vertical Trace Dim

Was the scope left on constantly on or used heavily in it's former life?

Could be phosphor burnout. Are there any signs of burn in marks (dark areas) where it's dim on the tube?

What happens when you turn the phosphor brightness knob up?

[joshnz]

Re: Tektronix 2235A Vertical Trace Dim

My new scope does that, makes it hard to see even on max brightness.
I read it it is to do with the rise fall time been to fast.

[Krankshaft]

Re: Tektronix 2235A Vertical Trace Dim

In that case probe an outlet (the secondary of a transformer is safer) and see if the sine wave is bright.

[Longbow]

Re: Tektronix 2235A Vertical Trace Dim

I agree with joshnz, if you are looking at a square wave with fast rise and fall times, it is normal for the vertical part of the waveform to look like that.

[Professor Peach]

Re: Tektronix 2235A Vertical Trace Dim

Yes, this is normal on a square wave.