HP 652A Operating And Service Manual page 70

Model 652A
CHANGE No. 7 Page 4-3 :
Replace Paragraphs 4-29 through 4-32 with the following
paragraphs:
4-29. R E G U LATED POWER SUPPL Y .
4-30. The regulated power supply provides a l l voltages
required by the test oscillator circuits. The power supply a
consists of +30 volt series regulated supply and a -25 volt
series regulated supply which is referenced to the +30 volt
circuit.
4-3 1 . TIle + 30 volt regulated supply is of the conventional
series regulator type. The emitter foHower Al Q2 is used to
Hlcrease the 190P gain of the circuit, thus impwving voltage
regulation. The ,. 30 volt adjustment , Al R4, sets the + 30
vnlt and - 25 volt supply output leveL
4-32. The -25 volt regulated supply is of the conventional
series regulator type and operates tile same as the +30 volt
supply, A current limiter, A I Q7 has been added to limit the
load current to a set value. When the load current exceeds
the set value, the current limiter conducts, causing the series
regulator 02 to reduce the output voltage level until the load
C;. tusing an excessive current is remo-vcd. Diodes AICR6 and
A1 CR7 protect the control transistor, A I 06, ag::linst short
circuits between the two voltage supplies, or short circuits in
the output of the -25 volt supply.
Page 5-8 :
Replace Paragraph 5-26 with the following paragraph:
5-26.
Power Supply Voltage Adjustments.
a. Connect de voltmeter to power supply
output, connector point l .(Refer to Figure 6-4.)
V
(+
b. Adjust A l R4 30
+ 30 V on de voltmeter. If AI R4 docs not have sufficient
range, change A I R5 * .
c. Connect dc voltmeter t o power supply negative
output, connector paint 2; de voltmeter should indicate
· 25 0.75 If negative supply output
V ± V.
tolerance, change value of
speCified output. Decrease value of A I R ! 3 * to increase
negative supply voltage; increase value
decrease negative supply voltage.
Page 5-9, Figure 5-7 and Page 7-3, Figure 7-2.
Change Al adjustments as in Figure C-2.
@,m,
.
!
I
Alel50
�
____ ,. _____
Figure C-2. A1 Adjustments.
positive
adjust) for an indication of
is
resistur
not within
A I R ! 3 * to obtain
of A ! R ! 3 * to
I
C
Appendix
C-3