HP BENCH Series Operating And Service Manual page 37

CHANGE 2: Change the component location diagram as shown in Figure A-2.
Change CR13 to Rect.250mA 200prv, 1N485B, 93332, Part No. 1901-0033.
CHANGE 3: In Table 6-4, Replaceable Parts, make the following change:
Fl, Fuse Cartridge lA 250V 3AG, 312.001, 75915, <$: Part No. 2110-0001.
CHANGE 4:
Page 3-1, Paragraph 3-2d. Change current limit as follows:
6215A 550 ± 10mA
6217A 310 ± 10mA.
Page 3-1, Paragraph 3-8. Change current limit as follows:
6215A 300 - 630mA
6217A 200 - 350mA.
Page 4-1, Figure 4-1. Delete amplifier 03.
Page 4-2, Paragraph 4-10. Change to:
4-10 When the external load resistance decreases, the output current increases until the current
limit is reached. The negative voltage developed across R33 and R50 forward biases CR4 control
ling the conduction of Q5 and Q7. Any further decreases in load resistance increase the negative
voltage on the base of Q5 which decreases the conduction of Q7. Thus, through feedback action
the output current is limited to the value at which CR4 conducts.
Page 4-3, Paragraph 4-21. Change to:
4-21 Current limiting occurs when diode CR4 becomes forward biased. Its anode potential is de
termined by the voltage at the base of Q5. The cathode potential of CR4 is determined by the volt
age drop across current limit potentiometer R50 which, in turn is connected across the current
sampling resistor. The cathode potential of CR4 is a function of the output current. As this current
increases, the drop across the sampling network increases, and CR4 will start to conduct. Conduc
tion of this diode clamps the base of Q5 to a potential which decreases the conduction of the series
regulator, thus limiting the output current. Potentiometer R50 permits the cathode potential of CR4
to be varied and thus changes the current limiting threshold.
Page 5-7, Paragraph 5-39c. Change:
475 ± 10mA to 550 ± 10mA
250 ± 10mA to 250 ± 10mA.
Page 6-5 and overall schematic at rear of manual. Change to:
C10-C12 fxd, ceramic .02[xf 600Vdc 3 Type ED. 02 72982 0150-0024 1
R16,17 fxd, comp 6.2K^ ±5% i W 2 EB-6225 01121 0686-6225 1
S2 Slide Switch, 3PDT, i knob.
Solder Terminal 1 llA-1138 82389 3101-1172 1
Delete: CR13, Q3, R14, R36, R37, andVR2.
Add: CR3 Rect. Si. 400mW lOprv 1 09182 1901-0460 1
On overall schematic at rear of manual:
Delete Q3 and connect wiper of R50 to cathode of CR4.
Delete R36 and connect R50 to +S.
Add CR3; connect cathode to TP3 and anode to +S.
A-3