Tektronix M 531, Инструкция по эксплуатации

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Maintenance— Type M
16. Waveform Distortion, All Channels
If you note waveform distortion on all channels when the
same fast-rise step signal is applied to each, you can assume
the distortion is produced in the Output Amplifier.
Examples of high-frequency distortion can be seen by
referring to Fig. 5-5, (b), (c) and (d), in the Calibration
procedure. If the distortion appears similar to one of these
illustrations, the usual cause is an improper adjustment of
the peaking coils (L5363 and L5373). If adjustment is neces­
sary, perform step 19 in the Calibration procedure.
An improperly adjusted H.F. PEAKING control produces
a distortion similar to that produced by maladjusted peak­
ing coils, but such distortion will only be visible at the
faster sweep rates. Shorted or partially shorted peaking
coils are often a source of high-frequency rolloff; this con­
dition is generally produced by hot solder falling on the
coils. Be especially careful when soldering around any of
the peaking coils.
17. Switching Transients Visible in Chopped Mode
If the switching transients are visible during multi­
trace chopped-mode operation, the trouble is in the
Chopped Mode Blanking Amplifier Q6364 stage (if you are
using the M Unit with an oscilloscope that has chopped-
mode blanking circuitry). Use a test oscilloscope to observe
and monitor the waveform at test point 20. Substitute for
Q6364. If normal operation is not obtained, check for an
open or shorted diode. If normal operation is not restored,
check voltages and resistances throughout the stage.
18. Short Circuit
If the oscilloscope used with the M Unit must be turned
off because the M Unit causes resistors in the oscilloscope
power supply to overheat, remove the M Unit from the
plug-in compartment. Use Table 5-1 in the Calibration pro­
cedure for resistance checks to isolate the trouble. When
you have found the cause of the trouble, replace the dam­
aged resistors (if any) in the oscilloscope. Recheck the
M Unit under operating conditions.
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