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If it was horizontal focus, that would be visible when you display a stationary dot in XY mode.What does a sine or triangle waveform look like?Is the triggering working correctly?
The power supplies do not look bad. That looks like a triggering problem.1. Try testing it using the external trigger input. It can be connected in parallel to the same source using another probe.2. Do the trigger calibration procedure in the manual.
X-Y Mode (with focus knob centered):
If you stick it XY, stick BW limit on and turn the brightness down and try and get the dot visible using minimal brightness and check astig and focus it should be possible to get it absolutely tiny.
The 465 vertical amp is a bit noisy due to the wide bandwidth compared to a lot of scopes. If you pull the bandwidth limit switch out to 20Mhz it’ll probably look sharper. 475 is even worse! (I have one)
So it was just the astigmatism. That is good news although I wonder how it drifted so far out of calibration.
I suspect that the last person who did the calibration didn’t do it properly.
Quote from: bd139 on September 04, 2021, 09:26:40 amI suspect that the last person who did the calibration didn’t do it properly.That might have been me. I couldn't follow the proper procedure for the vert amp adjustment because I don't have a 20mV ref, I'll borrow one of those and do it again.
I may have been jumping to conclusions assuming it was broken. Although initially the beam finder button was getting stuck in some intermediate state causing all sorts of weird issues. I fixed that with some DeOxit though.
Something weird I just noticed though, I think there's a DC offet when using the ADD function. If I set CH1 & CH2 both to GND coupling and centre the traces, when I select ADD the resultant trace is offset nearly 2 divisions from centre. I've got the case back on now, but I might have a closer look at that when I cal the horizontal amp.
I the two channels are centered during cal properly, the offset is virtually zero when you hit add. I bet there's a large offset if you hit INV as an example.