Tektronix 11A72 Manual page 16

Adding Waveforms
Front Panel
Error Messages
To set the amplifier's input coupling:
1. Select a displayed waveform.
2. Display the Control Menu using the control menu buttons. Refer to the oscillo-
scope User Reference manual under the topic Control Menus for more infor-
mation.
3. Touch the Coupling label to change the amplifier coupling.
11000-Series analog oscilloscopes allow the addition of any two displayed chan-
nels. Each channei must be in its linear operating range, which is assured if each
channel is displayed within the screen area before the channels are combined.
Portions of a waveform that are off-screen will not be valid when brought back
on-screen using another channel's input signal or offset. This general restriction
applies to any two-channel analog oscilloscope.
When the input voltage substantially exceeds 5 V rms, the amplifier will discon-
nect the 50 © input termination, and the oscilloscope will display the message:
Input channel N overload on LEFT/CENTER/RIGHT plug-in
where N = 1 or 2.
To reconnect the 50 © input termination, first correct the overload condition, then
select AC or DC coupling.
When an error occurs involving a plug-in amplifier, the oscilloscope will display
an error message.
For example, the following error messages may appear on the oscilloscope dis-
play:
Internal DAC overflow on channel N of LEFT/CENTER/RIGHT plug-in unit
A plug-in amplifier detected that a requested setting overflowed an internal DAC.
Such overfiow usually indicates defective hardware. in this situation, the amplifier
sets the DAC to the limit closer to the requested setting.
Bad Level 2 probe checksum on channel N of LEFT/CENTER/RIGHT plug-in
A plug-in amplifier detected that a Level 2 TEKPROBE failed or was improperly
connected.
Requested Coupling not available on Channel N of LEFT/CENTER/RIGHT
plug-in unit
A plug-in amplifier detected that a Level 2 TEKPROBE failed or was improperly
connected during either autoset or probe calibration.
Operation in Analog Oscilloscopes