Circuit Board Identification; Fuse And Connector Locations - Hach Sigma 950 Instrument Manual

9.3 Circuit Board Identification

9.4 Fuse and Connector Locations

Figure 18 Screw-Tightening Sequence
Note: Removal and handling of the circuit boards used in the 950 Flow Meter requires knowledge of
ESD (Electrostatic Discharge) precautions and the CMOS circuit components used in the meter.
Static electricity can damage the CMOS components of the meter when the boards are unplugged
and removed from the case. Precautions must be taken to assure a static-free work area prior to
handling the circuit boards.
The 950 Flow Meter contains two main circuit boards: the Base Board and the CPU
Board. The CPU board is located on the front panel assembly and the Base Board is
located inside the back section of the case.
In addition, a liquid crystal display (LCD) circuit board is located behind the CPU board.
The LCD board is an integral part of the LCD screen and contains no user serviceable
components (see Figure
Four fuses are provided to protect the 950 Flow Meter electronics from damage due to
short circuits or excessive current draw. Three fuses are located on the Base Board
(Figure 19) and one fuse is located on the CPU Board
Table 33 list the functions associated with the connectors and the fuses and their ratings
for both circuit boards.
17).
Maintenance
(Figure 20). Table 30 through
75