Fluke 5725A instruction manual Initial Access Procedure

Maintenance 6

Access Procedures

Warning

Follow the instructions under "Initial Access Procedure" to make sure high voltage has been bled off before you touch anything inside the 5725A.

If you work on a 5725A with the power cord attached, and/or you are not certain the high voltage has not bled off, do not wear a grounded wrist strap. Wearing a strap increases risk of dangerous electrical shock.

Use extreme caution when you are working inside the 5725A with the power connected. Use only non-conductive tools, and keep one hand behind your back to avoid making a circuit through your body.

The voltage output transistor heat sinks are at lethal voltage potential in ac V standby and ac V operate modes during normal operation, and possibly in any other mode after a failure. The heat sinks are exposed when any assembly is in the service position, and when the heat sink cover is removed.

6-7. Initial Access Procedure

Before accessing any module from the top or bottom of the instrument, proceed as follows to remove the top cover and verify that high voltage on the power supply capacitors has been bled off:

1.Turn off the POWER switch.

2.Remove the line power cord from ac line power.

3.Wait three minutes.

4.Remove the top cover by removing the screws accessible on the top surface (three front, three rear).

Warning

Before touching anything inside the 5725A, do the following steps to make sure high voltage has been bled off.

5.Refer to Figure 6-4 for the location of items mentioned in this procedure. Remove the five retaining screws on the High Voltage Amplifier assembly (A3). (Two screws secure each side rail, and one seats the board into a mating connector on the Interconnect assembly.) Lift the High Voltage assembly by pulling on the plastic wire-tie loops, pivot it, and insert its metal pegs in the two holes on the chassis as Figure 6-4 shows. This puts the High Voltage Amplifier assembly in the service position.

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