"robb" wrote in message
...
Silicon cured, CRT installed and tested.

Sorry no fireworks or shooting flames

thanks to Arfa, Jim, James, Sjouke etc...for the help.

Installed the new CRT and watched for all the symptoms and signs
people mentioned in the (sci.electronic.$$$$$) groups

No HV problems. But now the scope needs display adjusting to
suit the new CRT.

Problems:
==========
The display is skewed and the intensity and focus are off.

I was not expecting te new CRT to have hyper-intensity troubles.
That is... from no visible trace to oversaturated CRT brightness
is a very small range of knob motion maybe a 1/4-1/3 of he full
turn .

And the focus is very sensitive, touch sensitive ? was not
before.

And the internal probe calibration signal (.5 V @ 1 kHz) produces
a trace with fuzzy band for peaks ( 20 - 30 mV) or so wide. This
was not the case before maybe more like (5 mV ripple before CRT
swap)

So hopefully i can sort these problems out.


It sounds to me like this replacement CRT might not be quite as 'compatible'
as you had hoped ... :-( Maybe that's part of the reason that the PDA lead
was not long enough to fit in your chassis i.e. to stop such a substitution
taking place. As far as the trace being 'skewed' do you mean that it is not
perfectly horizontal, or that it is trapezoidally distorted ? If the former,
then most decent 'scopes have a trace rotation control somewhere. As far as
the brightness / focus issues go, that is likely to be quite difficult to
resolve, and will probably require changes to be made to the component
values in the resistor chains providing the biasing voltages to the various
electrodes. I would suggest that you will not get too far with that, without
having schematics for both the 'scope that you've put the tube in, and the
one that it came out of, so that you can make comparisons of values and
expected voltages. Just as a matter of interest, are the quoted deflection
sensitivities for both tubes the same ?

Good luck with it - I think you'ree going to need it, but it's nice to see
that a sense of experimentation still exists out there - it's the sort of
thing that I would have been playing with 30 years ago ...


Arfa