5400 Testing and Exchanging CPU Backup Batteries

Purpose:  Follow these steps to test and determine or exchange the three AA batteries used in the role of backup power for the instrument CPU.

Required Equipment:  3 AA batteries

                                          Digital Volt Meter

                                          12 Inch Adjustable Wrench

Reference:  Section 3: Service Procedures Page 3-17

1. Down OC, TC, and CO2 Purge channels with "set flag" button located on the right side of the site manager screen.

2. Press the RUN/STOP button once.

3. Select F1 (Immed).  This stops the collection of data.

4. Allow 10 minutes for the instrument to cool down.

5. Disconnect the inlet sample line inside the instrument; there is a Swagelok fitting located on the left side of the bulkhead just above the pinch valve.

6. Pull out the bulkhead to its fully outward position.

7. To check whether the batteries need replacing, measure the voltage across the test point labeled “BATV” in the lower right hand corner of the interface board and the ground test point labeled “DGND” in the same corner of the board.  If the measured voltage is less than 4.5 VDC, the batteries need replacing.

8. To replace the three AA batteries, remove the two clips that hold the batteries in their mounting.  Pull the old batteries out and replace them with three new ones.  Perform this exchange within an elapsed time of five minutes to avoid the loss of data stored in the battery-backed RAM (read-only memory).

9. Reinstall the clips to hold the new batteries in position. Test for 4.5 VDC (step 7).

10. Push the bulkhead into its fully inward position.

11. Replace the sample inlet line.