I own a Tektronix 475 that works well, but requires some realignment.
So far, I've been able to recalibrate the channel preamps and adjust
the input attenuators. Individually, each channel now produces an
accurate trace; however, I have a troublesome problem that I can't
quite figure out.
If I feed the same signal to both channels, invert Channel 2 (press
"INVERT") and then add it to Channel 1 (press "ADD"), I get a
flat trace that's offset by nearly -6 volts. The flat trace is good,
but no matter what I try, I can't get rid of this offset.
I've traced through the block diagrams and schematics and at this
point have pretty much ruled out any problem with the preamp board. I
fear the problem is down stream, probably in the signal combination
circuitry prior to the final vertical amplifier. Is integrated circuit
U370 the source of the problem? Is there an adjustment I've missed?
My eyes have grown weary tracing schematics, so I could really use some
sage wisdom here to save my eyesight.
-Dave Drumheller
So far, I've been able to recalibrate the channel preamps and adjust
the input attenuators. Individually, each channel now produces an
accurate trace; however, I have a troublesome problem that I can't
quite figure out.
If I feed the same signal to both channels, invert Channel 2 (press
"INVERT") and then add it to Channel 1 (press "ADD"), I get a
flat trace that's offset by nearly -6 volts. The flat trace is good,
but no matter what I try, I can't get rid of this offset.
I've traced through the block diagrams and schematics and at this
point have pretty much ruled out any problem with the preamp board. I
fear the problem is down stream, probably in the signal combination
circuitry prior to the final vertical amplifier. Is integrated circuit
U370 the source of the problem? Is there an adjustment I've missed?
My eyes have grown weary tracing schematics, so I could really use some
sage wisdom here to save my eyesight.
-Dave Drumheller