CHAPTER 3 MAINTENANCE PROCEDURES
3.2.1 Printed Circuit Board (PCB) Replacement
Repairs are not recommended on the PCB. Component parts of the PCB are not stocked by
Ohaus. Replacement is recommended rather than repairing.
Replace the PCB for any of the following reasons:
– Display is defective; characters missing or partial display.
– Indicator fails to calibrate properly.
– Display is erratic or unstable.
– Certain functions are not operational.
– Indicator does not operate at all.
1. Unplug the Indicator from the AC power source.
2. Remove the four screws from the Bottom Housing.
3. Carefully separate the Top Housing and Bottom Housing.
4. On the T31XW:
– Remove the Keypad connector ribbon cable by pulling it out.
– If the RS232 Interface is connected, disconnect its wire leads from the PCB’s
RS232 Terminal Block J7. (See Figure 1-1.)
5. On the T31P:
– Disconnect the battery.
– Pull the horizontal white-tab plug connecting the RS232 Interface to
the PCB’s Terminal J6. (See Figure 1-1.)
6. On both models:
– Pull the white-tab wire plugs connecting the PCB to the unit’s power supply.
– Disconnect the wire leads connecting the scale’s load cell to the PCB’s Load Cell
Terminal Block J5. (See Figure 1-1.)
7. Remove the four screws from the PCB. (…and, on the T31XW, the grounding cable
screwed to the PCB near the Keyboard connector.)
CAUTION
When handling the PCB, grasp it by the edges only!
Do not touch the foil side. Static discharge may damage some components.
8. Lift out the PCB.
9. Carefully re-position the replacement PCB over the screw holes in the Top Cover.
Re-insert and tighten the screws.
10. Reconnect the Cable Sets removed in Steps 4 – 6.
11. Perform calibration procedures. (See Section 1.8.)
12.
Perform testing procedures. (See Chapter 4.)
Ohaus Corporation www.ohaus.com
3-2
3000 Series T31 Indicators Service Manual
Summary of Contents for 3000 Series T31P
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