Hach Ultra MET ONE 237AB, User Manual, Page: 29 / 57

26
Maintenance
.
6.2.1 Battery replacement
WARNING
An explosion can occur if the internal battery is replaced incorrectly.
To replace the rechargeable battery pack:
1. Remove the top cover from the counter.
2. Disconnect the battery cable.
6.3 Printer maintenance
6.3.1 Clean the print head
To clean the print head:
1. Run the MET ONE 237 particle counter with a short sample period and enable the
printer.
2. When the print head is in the middle of the plate, turn off the power to the counter.
3. Take a piece of printer paper. Fold the paper in half and soak the paper with Isopropyl
alcohol.
4. Wedge the paper between the print head and the plate.
5. Move the paper to the left and right to clean the print head.
6.3.2 Correct light print
CAUTION
Do not make the print dark as it can cause the print head to be damaged by
overheating.
Important Note: Darken it just enough to make the print easily readable.
The printer PCBA (Printed circuit board assembly) is on the bottom of the chassis tray.
To correct the light print:
1. Remove the two screws as shown in section 6.2 on page 25 , step 2. This allows the
chassis tray to tilt up for access to the PCBA.
2. Make a very small adjustment to the Varicap on the printer logic board.
3. Turn the Varicap by about
1
/
16th
to the left to darken the print or to the right to lighten
the print.
Figure 11 Position of screws on the top cover of the counter
1 Position of three screws on one side (Screws that hold top cover)