Tube Replacement Chart; Power Supply Regulator Adjustment - HP 202A Operating And Service Manual

Sect.
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Page 4
4-8 TUBE REPLACEMENT CHART
TABLE 4-6.
4-9 P O W E R SUPPLY REGULATOR
ADJUSTMENT
TUBE
Vl, V2
V3
V4
V5, V6
V7, V8
V15, Vl6, V17
Vl8, Vl9, V20
V21
V22, V23, V24, V25
Resistance measured between inner and outer chassis
should be a t least two megohms with OUTPUT ter-
minals disconnected from panel ground o r a load.
This resistance check should be made before starting
the following adjustment procedure:
1) Connect the shorting s t r a p between the lower
output terminal and chassis ground. Connect the dc
voltmeter between B- and the inner chassis. The
voltmeter must not be grounded and the common
terminal should be connected to B-.
EFFECT
None. Variations in bottoming
voltage eliminated by clamps V7
and V8.
Frequency shift and distortion
increase due to contact potential
variations.
DC output level shift, probably
a s a function of amplitude con-
trol setting.
Possible change in frequency,
distortion, o r dc balance from
change in regulated voltages.
Same effect a s change in V3
possible, but to much less
degree.
Frequency change and unbalance
of triangle.
Change in dc output component,
independent of AMPLITUDE
control setting.
No effect
Possible change in
+
375 and
+
225 regulated voltages.
2) Connect the 202A to the power line and turn on.
The voltmeter indication should be between
+
190
and
+
230 volts with line voltage s e t to 115 volts.
READJUSTMENT
None.
Min. Distortion and Correct
Freq. Adj.
DC Bal. Adj.
Power Supply.
DC Bal Adjust.
Minimum Distortion and
Correct Freq. Adjust.
Min. Distortion and Correct
Freq. Adj.
Min. Distortion and Correct
Freq. Adj.
Set dc output component to
zero by R65, with amplitude
control min.
None.
/
Carry out procedure under
"Power Supply Regulator
Adjustment". Paragraph
4-9.
.
3) Measure the regulated output voltage between
B- and pin 2 of tube V5. Adjust control R11 to give
a voltage of
+
225 volts.
4) Measure the voltage between pin 5 of tube V5 and
B-. This voltage should be about
+
375 volts. Var-
iations in OA3 tubes can cause this voltage
to
be as
low as 365 o r a s high as 393.