I have a TEK TPS2012 (2 channel, 100MHz digital scope).
All functions are normal and the displayed measurement is ok down to 250us/div horizontal scale, but at lower horizontal settings (100us/div and lower) it displays a noisy signal of somewhat lower amplitude (although the amplitude varies with vertical scale, and the timebase varies with horizontal scale). Effectively the same situation with both channels. Using the Probe Comp signal source, there is a slight DC offset with Ch2, but otherwise the same as Ch1. See attached plots below for 250us, 100us and 1us time-base setting with the Probe Comp signal.
Self calibration fails at Step 7 of 16. No error shown in error log.
The troubleshooting tree indicates the Acquisition board needs to be replaced, as the Self test passes the first 5 tests.
I guess the fault could be in the input amplifier ASIC (before the isolation), and related to a buffer-gain amplifier section that is used for lower time-base settings. I can't easily see that this is a calibration setting issue, so am not yet keen to go through the Service Mode calibration procedure just to get stopped in that procedure half-way through.
I can still view higher time resolution detail by capturing a waveform and expanding it, although that is limited to 1us samples for the 250us time-base.
Has anyone changed an acquisition board in this series scope, or tried to faultfind on that board ?