525A
Modular-Level Maintenance
Evaluation of most problems can be made after the top cover is removed. Inside the
chassis are six circuit boards. They are connected to one another with point to point
wiring. The six circuit boards are the Main PCA, Keypad PCA, TC PCA, Lemo PCA,
Opto RS232 PCA, and the Display PCA.
Most of the Calibrator circuitry is located on the Main PCA. The Display PCA, Keypad
PCA, and Lemo PCA are mounted to the front of the chassis. The TC PCA is mounted in
the Output Block, and the Opto RS232 PCA is mounted on the rear of the chassis.
If the Main PCA needs repair, it is recommended that all other circuit boards be removed
from the chassis still assembled. Repair of the other circuit boards can be accomplished
while leaving them inside the chassis.
Disassembly
To open the Calibrator case, remove the six screws from each end and lift off the top
cover.
To remove all of the circuit boards while still assembled, do the following:
1. Stand the chassis on the front handles.
2. Remove the four nylon screws that attach the Display PCA to the front.
3. Remove the six screws that attach the Keypad PCA to the front.
4. Remove the five nuts that attach the Output Block to the front.
5. Remove the standoff nuts from the 9-pin D connector on the Opto RS232 PCA, if
present.
6. Stand the 525A back on its feet.
7. Remove the screws attaching the Opto RS232 PCA to the back, if present.
8. Remove the four screws through the transformer.
9. Remove the six screws that attach the Main PCA to the chassis base.
10. Carefully lift all of the attached circuit boards out of the chassis.
Reassembly
It is easier to solder the wires interconnecting the circuit boards before placing the
assemblies back into the chassis. The procedures in this section will explain how to
reconnect each of the circuit boards.
There are two wire sets available from Fluke. These wire sets are used to connect the
circuit boards. One set is for the front connections and the other set is for the rear panel
connections. Refer to Figure 2 for wire locations and Tables 3 and 4 for the detailed list
of front and rear panel connections.
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ACEC
OTHERS
