FLUKE FLUKE 88
Manual de Servicio

88
Service Manual

Referring to Figures 3-1 and 3-2, perform the following procedure to examine or replace the meter�s fuses: 1. Perform steps 1 through 3 of the battery replacement procedure. 2. Remove the defective fuse by gently prying one end of the fuse loose and sliding the fuse out of the fuse bracket. 3. Install a new fuse of the same size and rating. Make sure the new fuse is centered in the fuse holder. 4. Make sure that the Meter rotary switch and circuit board switch are in the OFF position. 5. Ensure that the gasket remains secured to the case bottom. Then, starting with the two snaps at the display end and finishing at the terminal end, cradle the case top into the gasket. 6. Reinstall the three screws from the case bottom.

3-10. Cleaning

Warning
To avoid electrical shock or damage to the meter, never allow water inside the case. To avoid damaging the meter�s housing, never use solvents on the meter. If the Meter requires cleaning, wipe it with a cloth that is lightly dampened with water or a mild detergent. Do not use aromatic hydrocarbons, chlorinated solvents, or methanolbased fluids on the Meter.

3-11. Input Terminals Water, dirt, or other contamination in the A or mA terminals may activate the Input Alert (beeper) even though test leads are not inserted. Such contamination can sometimes be dislodged by turning the Meter over and gently tapping on the case. However, Fluke recommends the following procedure as a much more effective treatment:
1. Turn the Meter off and remove all test leads. 2. Use a clean swab in each of the four terminals to dislodge and clean out the contamination. 3. Moisten a new swab with a cleaning and oiling agent (such as WD40). Work this swab around in the A and mA input terminals. The oiling agent insulates the terminals from moisture-related shorting. This preventive treatment ensures against future erroneous Input Alerts.

3-12. Function Encoding Potentiometer Perform the following procedure to clean the rotary switch potentiometer, which is screened on the back of the pca:
1. Remove the circuit assembly as described previously in this section under "Removing and Reinstalling the Circuit Assembly". 2. From the back of the circuit assembly, push the switch shaft in (see Figure 3-2), and remove the polymer thick-film (PTF) contact assembly. 3. Push and secure the ptf contact assembly back on the switch shaft.

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