Re: 465 Display Help Needed


dhuster@...
 

A few comments on what has been offered so far.

The characteristic fuzziness of a 465/475 and 7K scopes over their
earlier cousins (and which apparently is NOT your problem since you
describe major "focus" problems) is due to the inclusion of a scan
expansion mesh within the jug through which the electron beam has to
pass, causing a small amount of beam scatter. The mesh is there to
improve geometry.

If oscillations within the vertical system is the problem, then
inputting a sine wave will show a thicker trace at the peaks and a
thinner trace at the zero-crossing points. Also, you'll see the
signal from the vertical deflection plate pins on back to the source
of oscillation.

Open elements inside the jug can cause defocusing.

Don't forget that astigmatism and focus interact and one may be the
problem where the other is not. If you can "round up" an unfocused
stationary dot on the CRT with the astigmatism control, then focus is
your problem. If not, the astigmatism circuit may be at fault.

Make sure the LV power supplies are clean, correct and ripple-free.

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