Keithley 2001, Руководство по ремонту

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Disassembly
3-4
Perform the following steps to remove the A/D con-
verter board:
1. Remove Analog Top Shield

Position the chassis
right-side-up. The top shield is secured to the ana-
log board by a single screw. To remove the top
shield, simply loosen the screw and carefully lift
the shield out of the chassis.
2. Remove A/D Converter Board

The A/D con-
verter board is located near the front of the instru-
ment and is plugged into the analog board at
connector J1026. The board rests on three stand-
offs. Each standoff has a retaining clip to hold the
board securely in place. Gently pull each retaining
clip away and lift the board up until it clears the
clip. With the board clear of the three retaining
clips, unplug the board and pull it out of the chas-
sis.
3.5.3 Analog board
The analog board is removed through the top of the
chassis (see drawing 2001-051). Perform the following
steps to remove the analog board:
1. Remove Analog Top Shield

The top shield is se-
cured to the analog board by a single screw. To re-
move the top shield, simply loosen the screw and
carefully lift the shield out of the chassis.
2. Remove Pushrods

Remove the pushrods for the
INPUTS switch and the POWER switch as follows:
A. Using suitable pliers, grasp the INPUTS push-
rod near the switch and pull forward until it
disengages from the switch shaft. Remove the
pushrod from the chassis.
B. Turn the chassis upside-down. Grasp the rear
end of the POWER pushrod and pull upward
until it disengages from the switch shaft. Re-
move the pushrod from the chassis.
C. Return the chassis to the up-right position.
3. Remove Power Transformer

Remove the power
transformer (see drawing 2001-052) as follows:
A. Disconnect the transformer ground. A kep nut
is used to connect this green ground wire to a
threaded stud on the chassis.
B. Unplug the transformer. There are three plugs
for the transformer. Two are located on the an-
alog board at connectors J1024 and J1025, and
the third is located on the digital board at con-
nector J1032. Turn the chassis upside-down to
gain access to the plug on the digital board.
When Þnished, return the chassis to the up-
right position.
C. The transformer is secured to the side of the
chassis by a single screw. Remove this screw
and pull the transformer out of the chassis.
4. Remove AC Power Receptacle

Remove the AC
power receptacle as follows:
A. Disconnect the receptacle ground wire. A kep
nut is used to connect this green ground wire to
a threaded stud on the chassis.
B. Unplug the AC power receptacle cable. The
connector for this cable is located on the analog
board next to the power receptacle.
C. A spring clip on each side of the receptacle is
used to secure it to the rear panel of the chassis.
Press both clips inward and, at the same time,
push the receptacle out of the access hole in the
rear panel of the chassis.
5. Unplug Cable to Digital Board

On the left side
of the analog board there is a ribbon cable going to
the digital board. Turn the chassis upside-down
and unplug this cable at connector J1027 on the
digital board. Return the chassis to the right-side-
up position.
6. Disconnect Input Terminals

There are 10 input
terminal connections (Þve for the front and Þve for
the rear). Nine of these terminal wires are discon-
nected by simply pulling them off the pin connec-
tor on the input terminals. The front panel AMPS
terminal wire must be unsoldered from the analog
board. The solder connection for this white/blue
wire is located next to the INPUTS switch.
Terminal wire color identiÞcation for re-assembly
is provided as follows:
Front Rear
INPUT HI Red White/Red
INPUT LO Black White/Black
SENSE HI Yellow White/Yellow
SENSE LO Grey White/Grey
AMPS White White/Blue
7. Remove Regulator Clip

A metal clip is used to
transfer heat from two power supply devices (R101
and Q528) to the chassis. The clip is located on the
left side of the chassis towards the rear. The clip is
removed by pulling it upward. You may need to
use a small ßat-bladed screwdriver to pry it up.