Maintenance
Battery Replacement:
The 621 will display a battery symbol when the
internal 9V battery needs replacement.
Replace battery as follows:
1. Ensure instrument is switched off
2. Loosen the six cross head screws on the back
of the instrument
3. Remove the back cover
4. Remove old battery
5. Replace with new battery 9V NEDA 1604 or
equivalent
6. Reassemble the instrument in reverse order
from above being sure not to trap any wires
between the two halves of the case
7. Re-fit the six cross head screws being sure not
to over tighten
Cleaning:
Use a mild detergent and a slightly damp
cloth to clean the surfaces of the instrument.
