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Tektronix 2465 dot problem continuation

I first posted this problem at the end of another post, subject: tektronix 2465a delayed sweep time problem and tekman said that he had the same problem, and had to adjust the grid bias as well as all other hv adjustments. I haven't tired this yet, but I did take some pics while I was at work today.

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This shows the problem pretty well. Even with the trace intensity all the way down, the trace is still very bright, and the dots seem to be there most of the time (occasionally turning up the intensity will make them go away). Does this seem like a hv problem? I haven't dug too deeply into this scope yet, because I've been trying to fix the other delayed sweep with the 2465a. If you need any more information, I'll be happy to provide it, and I thanks for reading.

Thanks in advance, Steve Kamego Calibration Specialty Inc.

Reply to
steve
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all

information,

Thank you too for reading. Why do you don'T adjust the grid bias? This is your scope'S problem. Your problem... is another:

Don't expect answers when you are willing to follow these.

No, we don't need any further information about your problem.

scnr, Andreas

Reply to
tekman

On 10 Mar 2005 04:50:24 -0800, "tekman" wrote: Apologies tekman, I have been so busy I didn't say that the same day I posted this message, I went in and adjusted the grid bias, and as you said, it fixed the problem completely. Many thanks for your help, sorry I didn't give you credit earlier, we've been desperately trying to keep our heads above water.

Again, thanks for your advice, and I hope I didn't inadvertantely offend you, I do sincerely appreciate it.

Have a good one, Steve

Reply to
steve

steve wrote in news: snipped-for-privacy@4ax.com:

If the dot problem reoccurs,I would suspect the Z-axis hybrid amp,or cold solder joints on the HV PCB.

--
Jim Yanik
jyanik
at
kua.net
Reply to
Jim Yanik

Thank you Jim, you've been most helpful as well. I will look into the hv board next week, once we get some customer units out.

Just a side note, on the 2465a, I tried changing out the capacitors for the sample and hold circuit with no luck. I found there is just an offset in the error, which is constant, iirc .0568*main time. I have just been subtracting this from the measurement with deadly accurate results. It seems odd to me that the offset is this constant. Unfortunately, we only have the non-a service manual at work. Maybe I can convince them to get a newer manual, hopefully fix this problem, because it's a wonderful scope.

Anyway, thanks for all the help everybody, I do appreciate it.

Steve

Reply to
steve

Alright Steve, we will not hang you for this ;-)

hth, Andreas

Reply to
tekman

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