DIYbanter - Tektronix 465B Focus Problem

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February 3rd 06 01:32 AM

Tektronix 465B Focus Problem

The traces on my 465B scope are bright but a bit out of focus...I have
heard of resistor problems in the focus control voltage divider in
other models that have caused this same problem. I checked the CRT
schematic and noticed the resistors in question are in a resistor
network of 4 resistors.

Any thoughts on this would be helpful.
Thanks
Mike Miller
Kansas City

James Sweet

February 3rd 06 05:52 AM

Tektronix 465B Focus Problem

wrote:
The traces on my 465B scope are bright but a bit out of focus...I have
heard of resistor problems in the focus control voltage divider in
other models that have caused this same problem. I checked the CRT
schematic and noticed the resistors in question are in a resistor
network of 4 resistors.

Any thoughts on this would be helpful.
Thanks
Mike Miller
Kansas City

What's the focus control do when you adjust it?

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February 3rd 06 01:02 PM

Tektronix 465B Focus Problem

The focus control seems to function correctly, but you can't quite get
the trace clear and sharp.

Jim Yanik

February 3rd 06 04:04 PM

Tektronix 465B Focus Problem

wrote in
ups.com:

The traces on my 465B scope are bright but a bit out of focus...I have
heard of resistor problems in the focus control voltage divider in
other models that have caused this same problem. I checked the CRT
schematic and noticed the resistors in question are in a resistor
network of 4 resistors.

Any thoughts on this would be helpful.
Thanks
Mike Miller
Kansas City

The thick-film resistor could be out of spec,or you could also have
astigmatism problem,or noise in the power supplies.
First,check the cathode V (-2960,IIRC)to see that it's in spec.Part of the
thickfilm network is the HV divider that sets the right voltage,part is the
focus network.(doublesided thickfilm)

465B was not known for a really sharp trace-it has a mesh lens at the end
of the electron gun structure.

--
Jim Yanik
jyanik
at
kua.net

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