I've got a problem with the Counter/Timer/Multimeter (CTM) function
of a Tektronix 2236 oscilloscope. The CTM is not operating correctly
when I try to measure the voltage on channel 1. When I try to measure
the DC voltage of channel 1 (DC Coupling), the fluorescent display
reads "DC OUCH" indicating an overvoltage EVEN when NO voltage is
being applied. When I try to measure the AC voltage of channel 1 (AC
Coupling) the fluorescent display reads "AC 0.0013" (or somewhere
around there) regardless of what voltage is applied to channel 1.

The CTM measures voltage correctly when I use the multimeter
connector inputs on the right side of the oscilloscope. Therefore, it
appears that CTM is basically functioning, but there is some sort of
problem in the coupling of the channel 1 signal into the CTM.

Anybody familiar with this problem?

Thanks, Michael