Myron L 729II - Manual (Page 21)

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3. CHANGING ANALOG METER SCALE (DIAL)
After changing ranges on an analog model 750II it may be nec-
essary to change the meter scale (dial). The following steps will
guide you through the change. Please read caution carefully.
Exercise extreme caution while working on meter. Meter
movement, and/or pointer (needle) may be damaged beyond
repair. It is recommended only qualified personnel change
scales.
DO NOT allow dust to enter the case while it is open.
Failure to follow these instructions may cause irreparable
damage, and will VOID the warranty.
Briefly -
The meter is removed from front panel (except OEM models).
The cover is removed.
The hex screws retaining the scale are removed, and scale
is slid out the top.
New scale is slid in place, and screws reinstalled.
Cover aligned, installed and zero set.
Physical
For OEM models skip to #4.
1. Using a wrench, nut driver or pliers remove the two
(2) large nuts retaining the circuit board wiring harness
connectors. Red wire is PLUS (+),
Brown wire is MINUS (-). See figure II.G.4.
2. Using a standard slot screwdriver remove the four (4)
screws, and the backing plate holding the meter to the
front panel as shown in figure II.G.4.
3. Remove meter. Do not lose the gasket between the
meter and the front panel it must be reinstalled upon
reassembly. See figure II.G.5. Align gasket to front
panel so as the gasket does not show when meter is
assembled to front panel.
4. Using a wide blade standard slot screwdriver, starting
at a bottom corner, CAREFULLY pry the clear plastic
cover loose from the movement case. See figure II.G.6.
5. Using a 1/8” (3.2mm) hexdriver, remove the two (2)
small screws holding the scale (dial). See figure II.G.7.
6. To remove the scale, lightly press on bottom of scale,
the top will lift up. Be extremely careful not to bend the
pointer (needle) or to move the Zero Adjust (ZA).
See figure II.G.7.
7. Grasp top and slide scale slowly out from top. Be
extremely careful not to bend the pointer (needle) or to
move the Zero Adjust (ZA). See figure II.G.7.
8. Reverse the above procedure using the new scale.
NOTE: While replacing the clear plastic cover, ensure the
ZA screw pin on the cover aligns with the inverted “Y” shaped
slot on the meter movement. See figure II.G.7.
IF, the inverted “Y” shaped slot is inadvertently moved -
BEFORE installing cover:
a. Re-center the inverted “Y” to the meter case as
shown in figure II.G.7.
b. Center the Zero Adjust (ZA) PIN on the clear
plastic cover as shown in figure II.G.8.
9. Using a standard slot screwdriver, ensure the ZA is
operating - pointer swings left and right when turning
the ZA with a standard slot screwdriver. See figure
II.G.9.
10. Set Meter ZERO as shown in figure II.G.9.
11. Reinstall meter to front panel, reversing steps 1-3
(except OEM models).
GASKET
Harness to Main
CB Connector
Backing Plate
METER
Mounting Screws (4)
BROWN WIRE RED WIRE
+
CLEAR COVER
Pry Here Carefully
CASE
Figure II.G.5
Figure II.G.4
Figure II.G.6
!
CAUTION - READ FOLLOWING CAREFULLY