We had a cust send in a TDS3012B which won't trigger off any signal less than 2.5 divisions in DC coupling, and .7 divisions Noise Reject for signals below 50MHz, up at 100MHz the sensitivity is a little lower, say 3 div & 1 div, respectively. The manual states specifications as .6div for DC & 3.5 times the DC limit for noise reject below 50MHz, going up to 1 div for 100MHz. What could have caused this? Noise Reject has higher sensitivity than plain DC coupling?
We ran through the adjustment procedure, it passes without problem, all self tests pass, and the unit passes all other sections of the performance verification. We took the scope apart to make sure it wasn't anythign loose, but it looks like basically a single board deal, nothing to come loose.
Any ideas besides $1200.00 to send to Tek for repair?
Thanks, Steve