HP 4262A User Manual

™
Model 4262A
8-49. PROTECTIVE DIODE REPLACEMENT
(CR4, CR5, CR6 and CR7).
To replace protective circuit diodes connected to
UNKNOWN terminals (Low side), perform the
following procedure:
a. Remove top trim strip from front frame (use
a screwdriver to lift out the trim).
b. Remove the two left hand screws from among
the four screws located at the top side of the
front frame.
c. Tumn instrument upside down.
d. Remove the two right-hand screws from
among the four screws located at bottom side
of the front frame.
e. Carefully pull unknown terminal binding
posts forward and front panel assembly out.
CAUTION
DO NOT USE EXCESSIVE
FORCE OR WIRE CONNECTIONS
TO UNKNOWN TERMINALS
MAY BREAK.
f. Disconnect flat cable 40 pin connector A2W2
from the plug mated with A21 board
assembly. See Figure 8-14.
Section VIII
Paragraphs 8-49 to 8-51
g. Disconnect flat cable 40 pin connector A2W1
from the plug mated with mother board. See
Figure 8-14.
h. Unsolder wire leads to diode and disconnect
diode from the binding post soldering lugs of
UNKNOWN terminals.
i. Install new diode. Solder wire leads to new
diode.
8-50. ZERO ADJ CONTROL POTENTIOMETER
(R4 and R5) REPLACEMENT.
a. Perform steps a through g of paragraph 8-49
Protective Diode Replacement.
b. Remove retaining screw @ shown in Figure
8-13.
c. Remove the potentiometer retaining nut and
unsolder wiring leads to the potentiometer.
d. Install new potentiometer.
8-561. A2 KEYBOARD AND DISPLAY BOARD
DISASSEMBLY.
a. Perform steps a through g of paragraph 8-49
Protective Diode Replacement.
b. Remove the 8 screws (@through in Fig-
ure 8-14) fastening A2 board to front panel.
Figure 8-14. A2 Keyboard and Display Board Disassembly.
8-27

HP 4262A Specifications

General

Brand	HP
Model	4262A
Category	Measuring Instruments
Language	English