OHAUS AV114C, Service Manual

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3-1
CHAPTER 3 REPAIR PROCEDURES
3.1 REPAIR PROCEDURES SMALL FRAME AS and AV MODELS
This section of the manual contains detailed disassembly procedures of the AV and AS model
balances. There are two physical sizes of balances for the AV and AS models (large and small). This
section deals only with the small frame models. Housing measures 7.6 x 10 / 19.3 x 25.4 in/cm.
Section 5 of this manual contains exploded views and associated parts lists for all models. Refer to
Section 5 drawings before disassembling the balance. It should be noted that components inside of
the balance are delicate and need to be handled with care. The small frame AS and AV models contain
strain gauge load cells. It is imperative that the Load Cell should never be subjected to any excessive
torque, stress, or abrasion as damage may result. Once the balance has been disassembled, any
small scratch or abrasion made to any of the Individual Strain Gauges will render the entire Load Cell
unusable. The Main Printed Circuit Board, RS232 Interface Printed Circuit Board (on some models)
and the LCD and Backlight Board contain integrated circuits which employ CMOS technology,
therefore, caution must be exercised so as not to subject any of these components to static electricity
discharge. When servicing, a wrist Ground Strap with a 10 Megohm series resistor to earth ground is
highly recommended. The Printed Circuit Boards should be handled by grasping the edges only and
never placing fingers on any of the runs or traces.
3.1.1 Opening the Balance
To disassemble the balance, refer to Figure 3-1 on the next page that illustrates all of the Adventurer
Pro and Adventurer SL models. Components shown on top of the balances must be removed before
gaining access to the inside of the balance.proceed as follows:
Always use an antistatic kit!
1. Turn the balance off and if using an AC Adapter, disconnect it from the balance.
2. On balances containing a draft shield, remove the draft shield.
3. Remove the Pan from the balance. Pan sizes and shapes vary.
4. Remove the Pan Support from the balance.
5. Remove the Wind Ring on round pans and Adapter ring on square pans.
6. Remove the 2 screws from the top of the balance, then remove the EMC Plate.
7. If a battery is being used, hold the balance on its side without touching the Load Cell Cone.
Remove the Battery Compartment Cover as shown in Figure 3-2. Remove the 4 AA
batteries from inside the battery compartment and replace the Battery Compartment Cover.
8. Remove the 4 Feet by unscrewing each counter-clockwise.
9. Remove the 4 cover screws. The screws are in deep recessed holes. See Figure 3-2.
10. Turn the balance over in an upright position and carefully lift the Top Cover from the
balance Bottom Housing. Be careful as the Top Cover is connected by a cable to the
Main Board Assembly.
10. Unplug the cable from the Main Board Assembly. Set the Top Cover aside.
11. After repairs and or adjustments have been made, reassemble the balance in the reverse
order.