Tektronix TYPE Z PLIG-IN Instruction Manual page 26

Calibration — Type Z
Preset the Z Unit front-panel controls as follows:
POSITION
A VOLTS/CM
B VOLTS/CM
Both AC-DC switches
Mode
VAR. ATTEN.
COMPARISON VO LT­
AG E Polarity
COMPARISON VO LT­
A G E Range
Check to see that the COMPARISON VO LTAG E Helidial
reads exactly zero when the control is rotated fully counter­
clockwise. If the dial does not indicate zero, use an 0.050-
inch alien wrench to loosen the setscrew in the knob. Set
the dial for exactly zero indication and then tighten the
setscrew. To check the higher end of the dial, rotate the
COMPARISON V O LTA G E Helidial to its fully clockwise
position. The dial should indicate 10.000 or slightly higher.
Remove the left side panel from the oscilloscope.
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.
W A R N IN G
Do not touch transistors!
exist on transistor cases.
be rep laced , turn o ff the pow er.
CALIBRATION PROCEDURE
1. Check V o ltag e M easurem ents.
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
F ig . 5 - 1 . Lo cation of com ponents
the step 1 v o lta g e m easu rem ents a re m ad e.
5-2
Midrange
.05
.05
DC
TEST
Fully Clockwise
0
100 V
Con­
Dangerous potentials
If a transistor needs to
an d test points w h e re some of
IN T E R C O N N E C T IN G
PLU G
F ig . 5 - 2 . A n o th e r v ie w o f the Z U n it sh o w in g location of re m a in ­
in g com ponents an d test points d escrib ed in step 1.
within the range of 95-115 volts and within 3 volts of each
other.
(b) Connect the VO M between pin 7 of V7613 (see Fig.
5-2) and ground. Place the COMPARISON VO LTAG E Po­
larity switch to the + position and set the COMPARISON
VO LTAG E Helidial to 10.000. The meter should read approx­
imately 100 volts. Place the COMPARISON VO LTAG E Pol­
arity switch to the — position. The meter should now be
reading approximately — 100 volts. Set the COMPARISON
VO LTAG E 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.
TABLE 5-1
READ LO CA TIO N
0.17 to 0.23 V*
Emitter-to-base
Q7672.
0.17 to 0.23 V*
Emitter-to-base
Q8672.
5.7 to 6.7 V Drop across RT-6 zener diode
D7675.
5.7 to 6.7 V Drop across RT-6 zener diode
D8679.
+ 12.2 V Junction of V8623 filament
lead (blue and orange tracer)
and R8691.
+ 6 5 to + 70 V Terminals 1 and 3, intercon­
necting plug.
+ 75 V Terminal 15, interconnecting
plug.
- 9 8 V Pin 4 of V7618.
- 1 3 8 V Base of Q7618.
+210 V Junction of R7645 and R8645.
* 0 .3 to 0 .6 V , in T yp e Z U n its SN 101 to 1 6 5 9 .
P IN 7 ,
F ILA M E N T A N D R 8691
FIG . N O .
drop across 5-2
drop across 5-1
5-2
5-1
5-2
5-2
5-2
5-1
5-1
5-1