Tektronix Type Z Instruction Manual page 24

Calibration — Type Z
Preset the Z Unit front-panel
PO ITION
A VOLT /CM
B VOLT /CM
Both AC-DC switches
Mode
VAR. ATTEN.
COMPARI ON VOLT­
AGE Polarity
COMPARI ON VOLT ­
AGE Range
Check to see that the COMPARI ON VOLTAGE Helidial
reads exactly zero when the control is rotated fully counter ­
clockwise. Rotate the control fully clockwise.
should read about one half a minor division over 10.000
or a reading of 10.005. If the Helidial does not read ex ­
actly as described, loosen the set screw with 0.050" alien
wrench and set the Helidial for correct readings. Tighten
set screw.
Remove the left side panel from the oscilloscope. Con ­
nect the plug-in cable extension between the Z Unit and
the oscilloscope vertical plug-in connector. Connect the os ­
cilloscope power cord to the nominal voltage source for
which it is wired and turn on the power.
Do not touch
exist on transistor cases. If a transistor needs to
be replaced, turn off the power.
CAL BRAT ON PROCEDURE
1. Check Voltage Measurements.
Use the VOM to make the following measurements:
(a) Measure the voltage drops across the 105-volt zener
diodes, D7621 and D8621 (see Fig. 5-1). The drops must be
Q8672
D8679
Fig. 5-1. Location of components and test points where some of
the step 1 voltage measurements are made.
5-2
htt ://manoman.sqhill.com
controls as follows:
Midrange
.05
.05
DC
TE T
Fully Clockwise
0
100 V
WARNING
transistors! Dangerous potentials
BASE OF
D8621
JUNCT ONS OF
R7645 AND
R3645
P N 4,
V7618
D7621
The dial
NTERCONNECT NG
PLUG
Fig. 5-2. Another view of the Z Unit showing location of remain ­
ing components and test points described in step 1.
within the range of 95-115 volts and within 3 volts of each
other.
(b) Connect the VOM between pin 7 of V7613 (see Fig.
5-2) and ground. Place the COMPARI ON VOLTAGE Po ­
larity switch to the + position.
approximately 100 volts. Place the COMPARI ON VOLT ­
AGE Polarity switch to the — position. The meter should
now be reading approximately — 100 volts.
PARI ON VOLTAGE Polarity switch back to 0.
(c) Check the voltage readings listed in Table 5-1. Those
listed from + 12.2 volts and on are obtained by connecting
the VOM between the given location and ground.
READ
0.3 to 0.6 V
0.3 to 0.6 V
5.7 to 6.7 V
5.7 to 6.7 V
+ 12.2 V
+ 65 to +70 V
+ 75 V
-98 V
-138 V
+210 V
P N 7,
F LAMENT AND R8691
The meter should read
TABLE 5-1
LOCATION
Emitter-to-base drop across
Q7672.
Emitter-to-base drop across
Q8672.
Drop across RT-6 zener diode
D7675.
Drop across RT-6 zener diode
D8679.
Junction of V8623 filament
lead (blue and orange tracer)
and R8691.
Terminals 1 and 3, intercon ­
necting plug.
Terminal 15, interconnecting
plug-
Pin 4 of V7618.
Base of Q7618.
Junction of R7645 and R8645.
et the COM ­
FIG. NO.
5-2
5-1
5-2
5-1
5-2
5-2
5-2
5-1
5-1
5-1