Register Ring Replacement; Piezo Replacement - Casio PRT-40C Repair Manual

8-3 Register Ring Replacement

Tool used
NO. Code No.
1 1904 5153 HP-fingerstall (two set)
2 1901 9524 Case opener A
3 1901 9521 Silicone grease coating case
The bezel provided on the upper surface of the watch case that rotates is referred to as a register ring.
A packing/O-ring is installed between the case and register ring so that the register ring rotates smoothly.
In addition, a spring/leaf is used on some models to prevent the register ring from rotating in the
opposite direction.
When the register ring suddenly is no longer able to be rotated or the rotary torque becomes extremely
heavy, this is frequently caused by a broken packing/O-ring.
When this happens, remove the register ring and replace the packing/O-ring.
When removing the register ring from the case, open the case by inserting a case opener A between
the case and register ring.
There are some models in which the gap between the case and register ring is slightly wider for
inserting the case opener.
When attaching the register ring, it is usually pressed onto the case from above until it catches on the
case. Use the hand press for the attachment.
Furthermore, there are many cases in which the register ring, panel and tape/adhesive (for securing
the plate) supplied from Casio are only available as separate parts for those register rings of the MD,
LD and AD series. In this case, order all three parts from Casio and assemble them into a single unit
before installing on the watch.

8-4 Piezo Replacement

In nearly all watches equipped with an alarm, a piezoelectric device on the inside of the watch cover/
back sounds an alarm as a result of a spring/coil and so forth contacting a P.C.board.
If this piezoelectric device is cracked, the alarm will no longer be sounded and the piezoelectric device
must be replaced.
Some piezoelectric devices are supplied in the form of a cover/back ass'y in which the piezoelectric
device is already installed in the cover/back, while other are supplied as individual parts referred to as
piezo.
In the case of the latter, a piezo must be available when replacing the cover/back.
The procedure for attaching the piezo to the cover/back is as described below.
Tool used
NO. Code No.
1 1901 9524 Case opener A
2 1901 9522 Hand press
3 Hair drier
Tool name
Tool name
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