453 Sweep Problem


This 453 serial number is 25900 and Mod. 210H. It is very clean and was rescued from being scrapped about 15 years ago. Has always been dependable and accurate until now. It is an old IBM scope.

I can't get a good waveform with the Time/Div knob if the frequency is over 50khz. Even then it is very touchy. I'm using my Tektronix 191 Constant Amplitude Signal Generator. It has always been spot on in the past.

Here are some pics. The problem is the same on both A and B channels.

From 1khz Cal connector on scope. There is no change in the waveform no matter where you set the Time/Div knob.

Decided to first start checking all the voltages. The scope's Time/Div adjustments has no affect if the frequency is over 50khz. No being able to adjust for a square wave from the calibrator is confusing. I have a good grasp of basic electronics but new to Oscilloscopes.

What do you all think? I do have a manual for it with a full set of schematics. Need to get this problem resolved so I can check out my newly acquired 465 also in excellent condition.


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