Re: 7904A readout bounce


NigelP
 

So, further investigation demonstrates more of what I've already noted. Scenario: 7904A loaded with 2x 7A26, 7B92A, 7D15 and ALT set on both vertical PIs and mainframe set to ALT...... if I overlay all four traces on top of each other there is NO bouncing of the readout . As you increment any trace position towards top/bottom of the screen the bounce gets increasingly larger reaching around 0.1 major division (therefore readout bounce magnitude is a direct function of trace vertical position). Sweep speed in the region of 50mS/Div +/- some shows up nicely, but any variation of sweep speed simply varies the level of visual annoyance. Any combination of ALT setting produces the same result.

Similarly, substituting a 0587 Signal Standardiser into either PI slot and set up to perform the handbook "Thermal Comp" procedure, as mooted earlier in the thread, the readout bounces away merrily to the step waveform rising/falling.

Also using for example a single 7A26 set to CH1 and mainframe set to LEFT (so no ALT settings) the readout shifts up and down according to PI vertical position setting.... a direct and linear relationship between SHIFT potentiometer setting and readout vertical screen position. Readout movement is in anti-phase to trace shift movement.

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