Quick question re. Protek oscilloscope

[thesponge]

I have a Protek 20MHz scope that doesn't display the vertical line of a
square wave or a sawtooth. Sine and triangle are both fine. I have tried
both channels and every possible combination of settings to no avail.
Any ideas?
Cheers,
Dave

 

[Jamie]

thesponge wrote:

I have a Protek 20MHz scope that doesn't display the vertical line of a
square wave or a sawtooth. Sine and triangle are both fine. I have tried
both channels and every possible combination of settings to no avail.
Any ideas?
Cheers,
Dave
Is this a CRT type unit?

If so, the problem is the raise time, it's exceeding the scopes
CRT response time, and most likely it's driving circuits.
It sounds like you have a high BW input with a Low BW response.

If you have a calibration function for your 10:1 probe, use it to
adjust the corners of the square wave, it may ease the response
enough for you to see the vertical.

Also, bringing up the brightness should show you a faint vertical
line.

P.S.
This is common on a CRT scope, your Low Pass filer may help you here
if you have one.


http://webpages.charter.net/jamie_5"