HP 203A - Instrument Cover Removal; Power Supply А22 Adjustments

Section У
Paragraphs 5-10 to 5.15
Table 5-3
f. Set Model 203A PHASE LAG dial to 180°
g. Adjust Electronic Counter TRIGGER LEVEL
controls for stable reading near 1800.
h. Check Electronic Counter readings at 30°
increments on PHASE LAG dial. Readings shouldbe
within the values shown in table 5-3.
Table 5-3.
PHASE LAG
Phase Lag Check
ELECTRONIC COUNTER
Minimum
3550
250
550
850
21150
1450
1750
2050
2350
2650
2950
3250
5-10. INSTRUMENT COVER КЕМОМАЕ.
5-11. То remove either the top or bottom covers,
unscrew and remove the twocounter-sunk Phillips-
head screws which secure the coverto the instrument.
Then slide the cover toward the rear of the instrument.
To replace the cover, reverse the procedure.
5-12. ADJUSTMENTS.
5-13. The following test andadjustment procedures
should be performed only if it has been definitely
determined Y the Performance Checks given in
paragraphs 5-5 thru 5-9 that the Model 203A is out
of adjustment.
5-14. POWER SUPPLY A22 ADJUSTMENTS,
Note
Маке the following adjustments with FRE -
QUENCY MULTIPLIER switch in X100
position.
a. Supply Model 203A primary Зе from Vari-
able Transformer.
5. Set line voltage to nominal value (115 volts).
с.
Connect
DC
Voltmeter
and
AC
Voltmeter
tc
А22
(5).
(See
figure
5-21.)
d. Adjust A22R12 (-15 volt adjust) for DC Volt-
meter reading of -15.1 vde. АС Voltmeter should
read less than 1. 0 mv ripple.
e. Vary line voltage from 103 to 127 vac. DC
Voltmeter reading should not change more than x0. 2
vdc.
f. Connect DC Сайн: and АС Voltmeter to
A22 (13).
о. Adjust A22R20 (+15 volt adjust) for DC Volt-
meter reading of +15. 1 dc. The AC Voltmeter should
read less than 1.0 mv ripple.
5-6
Model 203 А
h. Vary line voltage from 103 to 127 vac. DC
Voltmeter reading should not change more than 20.2
vdc.
j. Connect DC Voltmeter and AC Voitmeter to
A22 (2).
k. AC Voltmeter should read less than 2.0 mv
ripple. DC Voltmeter should read -24.5 40.5 vde.
Note
It may be possible to bring the -24.5 voit
supply into specifications by a slight adjust-
ment of the -15 volt adjust (A22R12). Тһе
-15 volt supply must stay between -14.9
and -15.3 vde.
m. Varyline voltage from 103 to 127 vac. DC
Voltmeter reading should not change more than +0.4
vdc.
n. Connect DC Voltmeter to A22 (14).
p. DC Voltmeter should read +35 +5 хас.
а. Disconnect front panel shorting bar.
r
. Connect AC Voltmeterbetween chassis ground
and circuit common A22 (9).
5. Use an insulated tuning wand to adjust A21C1
(located onbottom of chassis) for a minimum reading
{refer to figure 5-8).
5-15. 4.995 MC OSCILLATOR AND 9:1 DIVIDER
(Al) ADJUSTMENT.
a. Connect 10:1 probe of Oscilloscope to base of
А103 and ground lead to ground plane of oscillator
board. (See figure 5-9.)
b. Set Oscilloscope controls as follows:
INPUT voe A e Vere АС e ea ners AC
SENSITIVITY сулуу Зо ox . 05 V/CM
SWEEP TIME еее 2 uSEC/CM
c. Adjust AIT1 for maximumamplitude of 5 mc
signal.
d. Move 10:1 probe to emitter of A1Q3.
e. Adjust A1L2 for eleven waveforms in 10 cm of
horizontal deflection. Adjust AlL2 so that the first
pip of signal is slightly larger than the rest (see fig-
ure 5-7, Waveforms 3 -5).
f. Repeat steps athru e until optimum adjustment
is obtained.
g. Move probe to A1 (5).
п. Adjust АТТ2 for maximum amplitude of 555 ke
Signal.
01760-3