This is the screen on my Tektronix 2465 oscilloscope when I power it up. It used to have the lines going all the way across and and when I would connect the probe to the stereo output (as a calibration test) I'd get a waveform.

But now there is no waveform at all, just faint vertical lines when I supply input to channel 1 using the probe. Has anyone else seen this problem before? If you have please tell me what causes it and how I might fix it!

Oscilloscope screen

  • 1
    \$\begingroup\$ Can you post a picture of the knob settings? This makes me think off-hand of being in X-Y mode and that maybe curious hands tried out the knobs :) But I'm thinking in any case it will be helpful to someone more experienced with these scopes. Btw, you can post a picture directly in your question, which allows folks to see it without clicking through a link. \$\endgroup\$
    – scanny
    Commented Mar 24, 2016 at 0:07
  • \$\begingroup\$ yes, I've put my scope on that setting before, by accident, and it did that. \$\endgroup\$ Commented Mar 24, 2016 at 0:34
  • \$\begingroup\$ See BEAM FIND feature described on page 65 of service manual... These older analog Tek scopes had this feature where a momentary button press would shrink the horizontal and vertical drive (much like in your photo), so in case the horizontal or vertical offset were adjusted far off-screen it could be noticed and corrected. Maybe the beam finder switch is stuck? \$\endgroup\$
    – MarkU
    Commented Mar 24, 2016 at 2:06
  • \$\begingroup\$ MarkU, I'll give that a try and see if it helps things. \$\endgroup\$
    – Mr X
    Commented Mar 24, 2016 at 5:32
  • \$\begingroup\$ Tried that, it has no effect. \$\endgroup\$
    – Mr X
    Commented Mar 24, 2016 at 15:52

1 Answer 1


You've had a failure in the horizontal sweep section or the horizontal amplifier.

If you're feeling masochistic, you can try to fix it yourself. Here, for instance is the service manual. You'll notice that, at the least, you need a working scope to troubleshoot. And you'll need access to Tektronix replacement parts.

Take it to a repair service.

  • \$\begingroup\$ yes, it's probably a capacitor in need of replacing. \$\endgroup\$ Commented Mar 24, 2016 at 0:29
  • \$\begingroup\$ Wow, thanks for the manual! Filed away just in case... 2465Bs are the greatest... \$\endgroup\$
    – user16324
    Commented Mar 24, 2016 at 0:35
  • \$\begingroup\$ Thanks WhatRoughBeast! There is a company in Beaverton, OR that will repair it....for a price: $975 flat rate with possible and extra $400. I am feeling masochistic and it might be a great learning experience to repair it myself. I got the machine last year for $300 so there's no way I'm gonna spend THAT much on repairs. \$\endgroup\$
    – Mr X
    Commented Mar 24, 2016 at 5:29
  • \$\begingroup\$ ALSO, before it started to malfunction like this, when I would turn on the oscilloscope with no input signal the screen would display 2 flat lines crookedly. The CRT has a manufacturing date stamped on it which is March 23,1983 so I wonder if the CRT might be worn out too. \$\endgroup\$
    – Mr X
    Commented Mar 30, 2016 at 23:00
  • \$\begingroup\$ "Crooked" horizontal lines might be either a misadjustment (rotation, skew, etc), placement of scope too near a magnet or CRT magnetized (degaussing coil), or a component which changed value (resistor, capacitor, etc.) \$\endgroup\$
    – rdtsc
    Commented Jun 20, 2016 at 20:43

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