Chapter 2 Diagnosis; Diagnosis; Scale Setup And Examination; Preliminary Checks - OHAUS FD SERIES Service Manual

2.

DIAGNOSIS

This section contains information needed to properly evaluate the reported problem and diagnose its
cause.

2.1 SCALE SETUP AND EXAMINATION

Set up the scale according to the Instruction manual. Allow the scale to stabilize to room temperature.
Examine the scale for signs of corrosion or physical damage.

2.2 PRELIMINARY CHECKS

Power up the scale using the customer's ac adapter. In the case where the scale will not power up,
check the ac adapter. Observe and record the error codes and software revision. Record all menu settings
as received.

2.3 TROUBLESHOOTING TABLES

Troubleshooting tables 2-1 through 2-7 identify actual types of problems that could be encountered with
the scale.
The troubleshooting tables refer to interconnection and wiring diagrams in this section to assist in locating
the problem.
SYMPTOM
Scale will not turn on with AC
adapter supplied.

2-1 SCALE WILL NOT TURN ON WITH AC ADAPTER.

PROBABLE CAUSE
Adapter defective.
DC input connector at the
bottom of scale is defective.
Membrane Switch defective.
Main PC Board is defective.
2-1

CHAPTER 2 DIAGNOSIS

REMEDY
Refer to Section 3.1 and check the ac
adapter voltage output. If voltage is
low or nonexistent, replace the ac
adapter. If OK, proceed.
Refer to Section 4.1 and open the scale.
Reconnect the ac adapter to the scale.
Check dc voltage on the Main PC Board
or test points as shown in Figure 3-2.
Voltage should read between 9 and 14
Volts (power off), and above 9 Volts dc
(power on). If voltage is not present,
check and replace the Harness. If OK,
proceed.
Refer to Section 3.2 and test the Mem-
brane Switch. Replace if necessary.
See Repair Procedure 4.2
If the scale fails to turn on with a new
Membrane Switch, the Main PC Board
should be tested in accordance with
section 3.4. The Main PC Board if
defective should be replaced. See Re-
pair Procedures 4.3. After repair, per-
form Operational Tests in Section 3.6.