Author Topic: Tek 465B X-axis beam problem  (Read 915 times)

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Offline tipex

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Tek 465B X-axis beam problem
« on: May 27, 2017, 02:43:02 pm »
Hi all! :)

I'm new to this forum. I was searching information about an oscilloscope and just found this amaizingly big community. I hope someone can help me ^-^

I have an old Tektronix 465B oscilloscope. Suddenly, the X axis is not displayed correctly anymore. The beam stops in the middle of the CRT screen. It's compressing all the X axis (temporal) information in almost a half of the screen, and the timespace is distorted (not linear) when the dot approaches the end of the beam (almost in the middle of the screen).
The Y axis is working correctly.

I'm attaching you a photo of the scope with a 1kHz signal in it. With the TIME/DIV set at 1ms, I should see one period/cycle of the signal in every division; however, as you can see, I'm seeing more than 2 cycles in one division. You can see also that the waveform is distorted at the end of the beam and is no longer lineal.

Do you have any idea of what can be happening?

Can it be the X-axis (horizontal) amplifier?  Or the CRT circuit?

Where should I start looking?

Any help would be really appreciated :-/O

Offline David Hess

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Re: Tek 465B X-axis beam problem
« Reply #1 on: May 27, 2017, 04:22:00 pm »
The problem is probably the output stage of the horizontal CRT amplifier but:

1. Check the low voltage power supply outputs for level and ripple.
2. Visually inspect the neck of the CRT to see if one of the horizontal deflection leads fell off.  These leads will be on the top or bottom.

Online james_s

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Re: Tek 465B X-axis beam problem
« Reply #2 on: May 27, 2017, 04:25:31 pm »
I had that happen once on mine, one of the wires came off the deflection pins and it had exactly the same symptom.

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