I recently started having a problem with the auto button of my SDS1102CML. When making measurements with the x10 setting of the probe it almost always expands the signal to fit the entire screen. But with the x1 setting of the probe most of the time it compresses the view (increases the time base and reduces the amplitude) so that you do not see any detail and have to adjust both the time base and the amplitude. Is there any particular reason for that?
P.S. This occurs mainly when visualizing the reference square wave of the scope. With an external signal there is no such problem.
Thank you for your attention,
this problem has been sloved, you can upgrade to the latest version from the http://www.siglent.com/cn/server/download.aspx?nodecode=105004002006
Exept that it is not repaired in version 5.01.02.13
(yes it works as long as keep DC coupling selected.)
This happend example if there is default settings before Auto setup or least no one have changed coupling to AC. )
How it works:
A:
Input setting DC
probe and scope set for probe factor 1x
Connect probe to 1kHz probe compensation output.
Works perfect,
Base line move to vertical center(if not there before), CH1 change to 1V/div and horizontal speed 250us/div
B:
Input setting AC
probe and scope set for probe factor 1x
Connect probe to 1kHz probe compensation output.
Autoset give poor result (fail)
Base line move to vertical center(if not there before) - this ok. Trigger level setting also ok, CH1 change to 2V/div (error) and horizontal speed 50ms/div (error), and signal is 1.5div high (-0.75 to +0.75div related to base line.)
C:
Input setting DC
probe and scope set for probe factor 10x
Connect probe to 1kHz probe compensation output.
Works perfect,
Base line move to vertical center(if not there before), CH1 change to 1V/div and horizontal speed 250us/div. Signal is 3div high, ( 0 to +3div related to base line)
D:
Input setting AC
probe and scope set for probe factor 10x
Connect probe to 1kHz probe compensation output.
Works perfect.
Base line move to vertical center(if not there before), CH1 change to 500mV/div and horizontal speed 250us/div. Signal is 6 div high. (-3div to +3div related to baseline)
Result:
B fails, A,C and D ok.
Note. It looks like it is related to frequency. If I use external generator for 1kHz and 3V square also B ok. But only if frequency is enough different as scope own 1kHz. Scope own 1kHz is derived from scope clock. If I use external 1kHz what is enough close scope own 1kHz result is same (fail) as with scope own 1kHz probe comp signal. For more fun, result is same if I use external signal but adjusted enough close to what scope think is very close 10kHz and same with very close 100kHz.