Tektronix Type 82 PLUG-IN Instruction Manual page 41

Maintenance—Type 82
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Calibrator signal to Chan.
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Test Point 6B
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Fig. 4-12. Checking X10 voltage gain. Set GAIN switch to X10 and V/CM switch to 10.
Part II—Troubleshooting
Switching Circuits
A. Signal Tracing
The technique for signal tracing the Switching Circuits is
similar to the technique described for low-frequency signal
tracing. That is the technique of checking the amplitude
and dc level of the signal at the various test points. A
wide-band test oscilloscope should be used for signal tracing
as described in the Test Equipment list (item 4b).
Waveforms at the various important test points are shown
on the Switching Circuit diagram. The MODE and CHOP
RATE switch settings {where needed}, amplitude, dc levels,
and sweep rate are indicated near each waveform for each
B. Voltage Table
As an aid to making detailed voltage checks in the
Blocking Oscillator Q590 and B.O. Bias EF @Q583 stages
Table 4-6 is provided. This table gives typical voltage
measurements obtained when the MODE switch is set to
ALTER. and CHOP. If the voltages are affected by the
setting of the CHOP RATE switch, then the voltages for
each setting of the switch are given.
Voltages obtained when the MODE switch is set to A
ONLY are indicated on the circuit diagram. If the MODE
switch is set to B ONLY, the channel B voltages will be the
same as those given for the A ONLY position.
Q583 and Q590 Voltage Measurements*
'Mode Switch Setting] CHOP RATE
location | ALTER. | CHOP. | Switch Setting
. +13.2 +11.1 |100KC
R580-R581 Junction 4.133 4119 TMC
" +13.0 +12.7 100 KC
Q583 Base +130 | 4126 1 MC
Q583 Emitter +129 +12.6 100 KC
Q590 Base 412.9 +12.8 1MC
+195 | 419.5 100 KC
Q583 Collect
omer | 4195 | 4197 1MC
. +12.5 +12.4 100 KC
Q590 Emitter 4125 411.0 1MC
Test Point 17 —0.08 —3.1 | 100 KC or 1 MC
Test Point 18 0 0 | 100KCor1 MC
*Free run the oscilloscope time-base at 1 psec/cm.
ADJUSTMENTS FOLLOWING REPAIR
Calibration checks to Make
When servicing the Type 82, a repair or an adjustment
may affect the operation of another circuit. The following
table shows the minimum calibration checks you may have
to make following a repair or adjustment. The areas listed in
the first column correspond to the names given to the major
circuits on the block and circuit diagrams.