The 112 is ok for the 110 measurement.
?
Resistance measurements depend on several variables including lead
polarity, meter type, and active device junction variables.
?
You need to make a dc voltage measurement on each of the deflection plates
(left and right, top and?bottom)?and report the measurements. Let's
see if the beam is anywhere near the center.
?
Next thing to check is the triggering. Are you getting a sweep?
?
That should keep you busy for a while :).
?
Tom
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----- Original Message -----
Sent: Sunday, January 20, 2013 3:45
PM
Subject: [TekScopes] 475 progress but
another road-block
?
So, with the help of the folks here and some troubleshooting, I've gotten
my 475 closer to being usable again.
However, I'm stuck at a new spot
now. I am getting almost perfect voltages at each test point except for the
110V TP which shows roughly 112.4 (which is still within tolerance, just not
ideal).
The odd thing is that when I test resistance to ground, only about
half of the points are within tolerance. 110, -15, U50, and 105 all show much
more resistance than they should. Especially -15 which is showing several K of
resistance (book shows it should be 480 ohms).
At some point, I also
found a trace that was broken and made the repair. I now get a display if I
use the beam finder button. However, I do not get a display without using that
button. When I adjust knobs on the front, that "beam found trace" does move
(mostly as I would expect). It doesn't seem to stay perfectly still in all
cases, but I'm assuming that is because something is still bad and causing
issues (including the resistance variances).
I do not have another
scope in order to test ripple. I've been trying to follow the troubleshooting
flow chart in the manual, but I may be getting confused. If I press the beam
finder and adjust the trace to the center, but then release the beam finder
button and still see no trace, should I be disconnecting the delay line as my
next test?
Or have I gotten ahead of myself?
-Josh
