Fluke 27 Service Manual page 33

2. Note the small bump at the center of tone edge of the momentary switch (S3-S6).
Place the momentary switch in the case with the bump toward the LCD display.
3. Place the digital pca in the top case with the connector toward the back of the
instrument and at the top of the case.
4. Install the four lower Phillips-head screws (H5) that secure the digital pca over the
momentary switch. Note that the momentary switch provides a seal between the case
and the digital pca. Install the screws using a diagonal sequence (i.e., upper-right,
then lower-left, then upper-left, then lower-right).
5. Install the two thread-forming, Phillips-head screws (H2) above the connector that
hold the top of the digital pca.
6. Install a new O-ring (MP4) on the rotary switch shaft (if not previously installed),
then place the Teflon washer (H1) on the rotary switch shaft, then install the rotary
switch knob in the front of the top case.
7. Lubricate the outer edges of the detent spring (MP5) with a very thin layer of silicon
lubricant, then install the detent spring over the rotary switch shaft. Detent spring
orientation is not critical.
8. Install the E-ring retainer (MP6) on the rotary switch shaft.
9. Rotate the rotary switch to the upper OFF position.
10. Place the rotary switch extension shaft (MP17) on the rotary switch shaft. Note the
small pointer on the base of the extension shaft. Place the pointer toward the center
of the display while the rotary switch knob is in the upper OFF position.
11. To reassemble the main pca/shield assembly, fit the top shield (MP9) over the
component side of the pca, taking care not to bend the connector pins. Make sure the
shield posts fit through the holes in the pca, and verify that the rotary switch is in the
upper OFF position.
12. Position the bottom shield (MP3) on the back of the pca with the stand-offs fitted
through the pca, then position the top shield on the top of the pca with the molded
stand-offs fitted through the pca.
13. Install the two Phillips-head machine screws (H8) and flat washers through the top
shield into the bottom shield. Install the three thread-forming Phillips-head screws
(H4) through the bottom shield into the top shield.
14. Carefully fit the main pca/shield assembly into the top case, taking care to ensure
that the connector pins on the main pca are lined up properly with the connector on
the digital pca, and the switch shaft extension aligns with the two rotary switch
wafers in the OFF position (do not use force). Engage the connector by pressing
lightly on the bottom shield at the case screw holes.
15. Install the four Phillips-head machine screws (H3) with lock washers that secure the
main pca/shield assembly to the back of the input terminals, again using a diagonal
pattern.
16. Install a new O-ring (MP13) on the bottom case (MP10), if it was not replaced
during disassembly, and position it at the beginning of the tapered area.
17. Place the bottom case on the top case, then start four new thread-forming screws
(H7) with rubber washers. (The new screws and washers are provided in the seal
kit.) Press the case halves firmly together, and using a number 2 Pozidriv
screwdriver, tighten the screws in a diagonal pattern (lower-right, upper-left, upper-
right, lower left), to ensure a proper seal.
Maintenance
General Maintenance Information
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