Re: 465 Display Help Needed


Kurt Graber <kurtg@...>
 

billw101@aol.com wrote:

Hello, I have been pulling problems out of a 465 that I recently
acquired. The last remaining problem is the inability to get a sharp
focus on the trace with any combination of intensity, focus or
astigmatism. I have checked everything in the CRT circuits with the
exception of the high voltage, crt bias and cathode bias, until I get
the use of an HV probe. Can anyone tell me if I am looking in the
right area or suggest any common failure modes? The low voltage
supplies all check good and noise free. Thanks for any help.

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A common problem or failure is the opening of the voltage divider circuit
that the focus and astig tap into.
I am unfamilier with your particular scope but the chances are good that one
of the resistors has opened up. I have seen many cases !!! you don't need a
HV probe , just take your meter and ohm them out. They will not appear burned
but they have a tendancy to open up due to the high voltage.......this will
cause an unsharp trace and many cases no trace at all (just a haze)...Good
Luck

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