Now you know...

Discussion in 'Radio Circuits, Repair & Performance' started by KL7AJ, Jan 14, 2020 at 4:34 AM.

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  1. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    Well, I thought my semi-favorite analog TEK scope was going flaky. Turned it on and what should have been a horizontal trace looked like a haystack. The text dealibobbers on the screen were all warped I figured it was some kind of power supply issue. As it turned out, one of our visiting rugrats had left a small speaker magnet on top of the scope. Removed the magnet and the trace straightened out.
    So....if you've got a warped sillyscope trace, look for new sources of magnetism. :)
    p.s. I do encourage the rugrats to twiddle all my no harm no foul. :)
    N4FZ, N0TZU and KA0HCP like this.
  2. K7MEM

    K7MEM Ham Member QRZ Page

    Yes, the old "magnet on the CRT neck" trick. I remember it from high school. That was right up there with the "selenium rectifier in the AC outlet" trick. Boy, that one was a stinker.

    When I was in high school (graduated 1967) the electronics class had work benches along two of the walls. The work benches were situated 90 degrees to the wall. They had a shelf along the back of the bench, for setting up test equipment. On the edge of every bench was open framed television, which were always running. Safety issues were not the same back then. Good thing they were only B&W TVs. But, unless we were working on the TV, it was always set so that it was facing away from us. We couldn't see it, but we were very resourceful.

    We could see the TV screen on the bench behind us, if we used a mirror. But with a mirror, everything was flipped left to right. So we figured out that if we swapped the horizontal scan connections on the deflection coil, the screen would be backwards and the mirror image was correct. Learning was so much fun back then.
    AA7QQ and W9FL like this.

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