Tektronix 321 Series Manual

TYPE 321 OSCILLOSCOPE
FACTORY
CALIBRATION PROCEDURE
Quick check for ong ends, unso dered joints, wire dress, etc. Preset a pots
and trimmers to mid-range. Check front pane contro s for position and operation.
1. CHECK POWER SUPPLY RESISTANCES TO GROUND
Primary of Power Transformer -- Infinite
10 Vo ts. Regu ated to Converter -- Infinite
The fo owing readings taken with Com. Lead of Ohmmeter on ground:
+45 200 Q
+45 Dec. 600 Q
+10 80 Q
+6.3 8 Q
+6.3 Dec. 8 Q
-10 1000 Q
-10 Dec. 1400 Q
-45 4000 Q
-720 5 Meg Q
*NOTE: These readings wi vary depending on range used. Use owest
possib e range.
1A. CHECK RESISTANCE ACROSS BATTERY TERMINALS
With common ead of ohmmeter on Neg. termina read 300 Q, reverse eads
and read infinite. Power switch off.
2. CHECK VOLTAGES AND REGULATION
Adjus 10 Vol s regula ed, (Check D.C. regula ion.) 105-125. Measure
vol ages from conver er.
TYPICAL MEASUREMENTS
+45 45.5 Ripple
5 mv
+45 Dec. 47 2 mv
+10 9.5 3 mv
+6.3 6.3 150 mv
+6.3 Dec. 6.3 100 mv
-10 -10 3 mv
-10 Dec. -11 2 mv
-45 -44 5 mv
-720 -720 750 mv
January i960 321-1

3. CHECK HI VOLTAGE (Acce erating) at cathode of V832 measure +3330 Vo ts.
k. CHECK SCALE ILLUM. AND POSITIONING CONTROLS
Check the SCALE ILLUMINATION contro . Check operation of the POSITIONING
CONTROLS♦ Free run trace and a ign trace with horizonta graticu e ines.
Push CRT forward against graticu e and tighten CRT c amp.
5. CHECK FOCUS AND ASTIGMATISM
Using norma intensity, disp ay about 2 major divisions of ca ibrator
signa . Adjust FOCUS and ASTIGMATISM for sharpest focus of the disp ay.
6. SET GEOM. ADJUST
Disp ay on y the rising and fa ing portion of the ca ibrator waveform.
Adjust GEOMETRY for straightest vertica ines.
7. SET VERTICAL AMPLIFIER DC BALANCE
Adjust the DC BAL. pot so that there is no vertica shifting of the trace
as the VARIABLE sensitivity contro is rotated from one extreme to the other.
8. DC SHIFT COMP.
9. SET VERTICAL AMPLIFIER GAIN
App y .03 V to the vertica INPUT jack on the 321 from the ca ibrator in
the test scope. Set the VOLTS/DIV switch to £1. Set the VERT. GAIN ADJ.
for 5 major divisions of signa disp ay. Switch from AC to DC. There
shou d be no change in gain. Check the VARIABLE sensitivity contro for
sufficient range.
10. CHECK VERTICAL AMPLIFIER BALANCE
With the VERTICAL POSITION contro centered, the trace shou d be within 1
major division of the graticu e center.
11. SET CAL AMP
12. CHECK COMPRESSION AND EXPANSION
With 2 major divisions of ca ibrator waveform disp ayed, position the
presentation to the top and bottom imits of the graticu e. Compression
or expansion must not be greater than .5 minor divisions. Check for
microphonics and hum.
13. ADJUST VOLTS/DIV SWITCH COMPENSATIONS
With the VARIABLE sensitivity contro turned comp ete y CW, and the
VOLTS/DIV switch in the .01 position, connect a 10X probe to the output
of the test scope ca ibrator and disp ay about k major divisions of
signa . Compensate probe. Adjust the attenuator compensation as fo ows:
January i960 321-2

VOLTS/DIV PEAKING ADJ. LEVEL ADJ.
.02 C4l8C C4l8A
.05 C4l6C C4l6A
^1 C4l4c C4l4A
1 C412C C4l2A
10 C410C C4lOA
Ik. CHECK ACCURACY OF VOLTS/DIV STEPS
Begin with the VOLTS/DIV switch in the .01 position and the ca ibrator
in the test scope set to .05 V. Check each range of the VOLTS/DIV
switch for the proper def ection. (±2$) NOTE: The accuracy of the
vertica ca ibration of the 521 is dependent upon the accuracy of the
test scope ca ibrator.
15. ADJUST HIGH FREQUENCY COMPENSATION
From the type 105 square wave generator app y a signa of approximate y
250 KC to the vertica INPUT of the 321. Set the VOLTS/DIV switch to the
straight through (.01) position. Adjust C508 for the best square wave
response.
16. SET STABILITY
Remove any signa from the vertica INPUT jack. Turn the TRIG. LEVEL
contro to AUTO. Rotate the STABILITY contro CW unti the sweep triggers.
Further CW rotation wi cause the sweep to free run. The STABILITY
contro shou d be positioned approximate y mid-way between the point at
which the sweep triggers and the point at which it free runs.
17. CHECK VERTICAL FREQUENCY RESPONSE
With the VOLTS/DIV switch on the .01 position, feed enough 50 KC signa
from the 190 into the vertica INPUT to obtain 4 major divisions of
def ection. Switch the 190 to 5 MC. The ver ical deflec ion should now
be not ess than 2.9 major divisions.
18. CHECK HIGH FREQUENCY TRIGGER
The scope must trigger on a 2MC signa .
19. CHECK TRIG. LEVEL. AC, INT.
Position the TRIG. LEVEL knob on the shaft so that the scope wi trigger
± on .5 major division of ca ibrator signa when the dot on the knob is
centered, (at zero). By adjusting the TRIG. LEVEL contro , it shou d be
possib e to trigger on 1 minor division of signa .
20. CHECK AUTO. TRIGGERING, INT.
When the TRIG. LEVEL contro is turned to AUTO, the scope wi trigger
± on .5 major divisions of ca ibrator signa .
January i960 321-3

21. CHECK TRIG. LEVEL, DC, INT.
The scope must trigger on .5 major divisions of signa within 2 major
divisions of the graticu e center on ± INT.
22. CHECK EXT. TRIGGERING
The scope shou d trigger on EXT. AC, DC, or AUTO with .5 V og signa .
23. SET HORIZONTAL GAIN
App y 10 psec markers from the 80 to the vertica INPUT. Set the sweep
speed at 10 pSEC/DIV. Adjust R338, HORIZONTAL GAIN to give 1 marker per
major division.
2k. SET SWEEP LENGTH
Adjust the SWEEP LENGTH contro (R176) for 10.5 major divisions of
horizonta def ection at 1 MILLISEC/DIV sweep speed with 1 mi isec
markers from the 80.
25. ADJUST MAG GAIN
Set the TIME/DIV switch to 10 pSEC.
App y 1 psec markers to the vertica INPUT. Pu VARIABLE TIME/DIV
contro to give 5X MAG. Adjust the MAG. GAIN contro (R348) to give 2
markers per major division. Check sweep timing in a ranges. (±2%)
26. SET .5 iiSEC DIV/TIMING
App y 1 psec markers to the vertica INPUT. Set the TIME/DIV switch to
.5 pSEC. Adjust C160L for 1 marker per 2 major divisions.
27. SET SLOW SWEEP ADJ.
Using 1 sec markers from the 180, switch the TIME/DIV to the .5 SEC
position. Adjust SLOW SWEEP ADJ. (R 67) to give 1 marker per 2 major
division.
28. CHECK Z-AXIS INPUT
Remove the grounding strap from the Z-AXIS INPUT and app y 10 V from the
test scope ca ibrator. At norma INTENSITY setting the 10 V shou d
intensify the trace.
29. CHECK EXTERNAL DEFLECTION FACTOR
Switch the TIME/DIV switch to EXT. HORIZ. and feed 10 V from the test
scope ca ibrator to the EXT. HORIZ. INPUT jack on the 321 . There shou d be
6.7 or more major divisions of deflec ion.
January i960 321-4

30. CHECK HOLD-OFF
Connec a 10X probe o he ungrounded side of C312. Free run he 321 sweep
and check for sufficien hold-off on all sweep ranges.
RANGE HOLD-OFF RANGE HOLD-OFF
.5 nsec 13 nsec 10 nsec 130 nsec
1 nsec 13 nsec 20 nsec 130 nsec
2 nsec 13 nsec 50 nsec 130 nsec
5 nsec 13 nsec
.1 Millisec .8 Millisec 10 Millisec 150 Millisec
.2 Millisec .8 Millisec 20 Millisec 150 Millisec
.5 Millisec .8 Millisec 50 Millisec 150 Millisec
1 Millisec 8 Millisec .1 Sec 150 Millisec
2 Millisec 8 Millisec .2 Sec 150 Millisec
5 Millisec 8 Millisec •5 Sec• 150 Millisec
MAKE NOTE OF CRT TYPE AND SERIAL NUMBER AND RECORD ON CALIBRATION RECORD.
32. CHECK OPERATION OF BATTERY CHARGER CIRCUIT.
Connec he scope o 117V wi h he power swi ch off. Wi h he ba ery pack
in place, connec he nega ive lead of he vol me er o he -10V regula ed
supply. Connec he + lead of he vol me er o he fron end of he 117Q
10W resis or on he lef side of he scope, (viewed from he fron ) Wi h
he swi ch in he DRY CELLS posi ion, he reading will be 0 vol s. Swi ch
o he 2.5AH posi ion and he me er should read 37-40V. Swi ch o he 4.3AH
posi ion and he me er should read 34-36V.
Now swi ch he scope ON and he me er should read 14-16V in he 4.3AH posi
ion, 16-18V in he 2.5AH posi ion and 0 V in he DRY CELL posi ion if he
charger is working properly.
33. CHECK BATTERY OPERATION
Remove he AC cord. Inser he ba ery pack. Hie scope should func ion
normally as long as he ba ery vol age under load is higher han 11.5 v.
34. CHECK DC OPERATION
Remove he ba ery pack from he scope and inser he DC cord. Connec he
ba ery pack o he black and whi e leads. (Nega ive o he whi e lead.)
The scope should opera e normally. Check be ween he black and green leads
for a resis ance of 13&»
Connec a DC supply o he black and whi e leads. Hie scope should regula e
from 11.5 v o 23 vol s.
Connec he DC supply o he whi e and green leads. The scope should regu
la e from 22 o 35 vol s.