I have a 2445B scope on which I can not adjust focus to obtain a clear sharp trace. The best focus is achieved somewhere in the middle of the range of the focus pot which leads me to believe that this isn't just a pot which has drifted.
This is a scope purchased under warranty. Should I return it or try to repair it? Any ideas what may be wrong?
How about the astigmatism control, usually a screwdriver adjustment on the front panel? Between that and the focus pot it should be possible to get a clear trace everywhere.
Does it do this with no input signal, or only when you have it connected to something? The 20 MHz bandwidth switch cleans the trace up nicely on my
2445, otherwise it is fairly broad.
If that doesn't do it, I'd go for the warranty first.
"Bob M." wrote in news: snipped-for-privacy@comcast.com:
This is good advice.IF all this fails,then you need a service manual,and check out the circuit description for the HV circuitry.The worst thing would be a bad Z-axis hybrid IC;not made any more,not available new,just from parts scopes.
Tweezing the astigmatism pot did actually help quite a bit. It's now probably usable. I was just looking at the DC traces and the lettering. This scope was shipped without proper (original) packing material and it may have just bonked the front panel pots a little.
My big concern is if the CRT is gassy - that is a killer when buying old Tek scopes. Even when you could get replacements they would cost as much as adding a room on your house!
I've heard that on 2215 scopes there is a resistor string focus setting network which drifts. I've looked at the schematic for the focus control electronics on the 24XX scopes and it is an actual DC amplifier. I don't think this is a resistor drift issue.
As I do have a parts scope available, I do also have the option to swap the high voltage boards. I don't know if that would cause the scope to go out of calibration, however.
Grant Erw> How about the astigmatism control, usually a screwdriver adjustment on the
Grant Erwin wrote in news: snipped-for-privacy@corp.supernews.com:
I've seen some of the small value ceramic tubular caps cause focus/astig problems.Leaky or shorted caps. This scope has dynamic focus tracking(with intensity changes). If you do swap the HV boards,recalibration should be done.
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