2465A vertical jitter


Gary Appel
 

My 2465A is exhibiting jitter in the vertical axis. This jitter is present in all - traces, cursors, and readouts. There is no jitter visible in the horizontal axis.


The input to U600, the vertical output amplifier - measured differentially at R405 and R404, is stable. The output - measured differentially at L633 and L628 displays the jitter. I've "tweaked" both R638 (Gain) and R639 (Vertical Center) to make sure it wasn't a faulty pot. No change.


I'm suspecting U600, but I'm not in a hurry to try to replace it. I have a spare main board with U600 on it, although I don't know if the IC is good. I would like to refrain from replacing U600 until I can eliminate any other problem areas.


Any suggestions on what else in the vertical output might be causing jitter? Has anyone seen this, and fixed it by replacing U600.


I do have a TDS360 available for troubleshooting.


Thanks,


Gary Appel

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