Re: 7T11 horizontal memory


cmjones01
 

I have now replaced the faulty R541 and R542. I also found that U572B, a Tek special op-amp, was dead, I think due to a careless slip of my scope probe. For now I've kludged a 741 in its place. Joy of joys, I have a horizontal sweep in equivalent-time mode! Still blanked in real-time mode. I think there's still something not right about the horizontal memory, which seems to only be used in real-time mode (or am I wrong?). Anyhow, when I select a real-time-mode sweep range, the output of U572B wanders up to about +12V and stays there. I do have real-time sweep on the way in to the horizontal memory, though. Will investigate further.

Chris

On Wed, Dec 5, 2018 at 06:07 AM, Albert Otten wrote:
One more suggestion. Set the 7T11 for MANUAL scan. Set the test scope at 5 or
10 us/div, trigger from the 7T11 pulse output. Then probe all TPs 512, 515,
525, 555 of the horizontal amplifier. In each period you will see one
horizontal line at a level determined by the SCAN knob setting. The level
increases from ground to some maximum when you rotate SCAN from left (ccw) to
right (cw). The amounts and ratios depend on the setting of the 7T11 time/div
within its range. At TP555 the maximum should always be 5 V.

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