[Test-Equipment] Tek 475 HV Arcing...

[R. Dahl]

Thanks to all who responded,

I guess I had better sit down and read the service book before doing much.
A previous owner had wrapped the mid-cable connector in the high tension
wire with rubber electrical tape, perhaps in an effort to fix it.  That is
where the arcing happens.  If the HV is that critical to calibration, then
it must be regulated.  Maybe that has failed in a higher voltage mode, thus
the arcing.  Hopefully, I can troubleshoot it at the regulator level as I
dont have a means of measuring the HV.   Im off to read the service book to
find out how to clean it without killing myself.

Ross
ve6ars



> Ross, ve6ars...
>
> I fully agree with Rolynn Prechtl, K7DFW, who advised NOT readjusting the
> HV.   Any change in the HV will change the CRT's sensitivity, both
Vertical
> and Horizontal, thereby affecting the calibration in BOTH V & H.
> Decreasing the HV will cause the CRT to become MORE sensitive and will
allow
> the sweep and vertical amplitude to INCREASE...  Increasing the HV will
> cause the CRT to become LESS sensitive and will allow the sweep and
vertical
> amplitude to DECREASE...  Connect a calibrated time-mark generator to the
> scope and vary the HV... You'll see what we mean...
>
> Perhaps a good cleaning will cure your arcing...  Be sure to thoroughly
> finish your cleaning by wiping away any soap or detergent residue with
> several CLEAN alcohol swabs... Don't allow any liquids to 'RUN'... keep
> wiping with clean swabs until ALL traces of foreign matter have been
> removed.  If you still experience arcing, a very light coating of 'CORONA
> DOPE' will fix the problem.  Don't GLOB it on... Use just enough to stop
the
> arcing.  Also, check for coronal discharge by switching off the room
> lights...  Switch off the 475, and wait until the power supply voltages
are
> completely discharged, ground the supplies, and the HV.  Then thoroughly
> clean all areas that had coronal discharges, as mentioned earlier...
>
> Never be afraid to try something new.
> Remember, amateurs built the ark,
> professionals built the Titanic...
>
> vy 73 de Larry, W1GOR
>
>