
To access the Model 1008’s internal PC boards, insert a small flat- blade screwdriver between the connector and the lip of the case and twist gently as shown in Figure 3 (below).
Figure 3. Opening the Model 1008’s plastic case with a small screwdriver
Both DIP switch S1 and S2 are marked with individual switch numbers 1 thru 4. Use these numbers, as well as the “ON” designation to orient the switch properly (see Figure 4, below). Use a small screw driver or similar instrument to set each individual switch.
| “ON” | ON | 
| 
 | 
| “OFF” | 1 | 2 | 3 | 4 | 
Figure 4. Close-up  of DIP switches S1 and S2, showing ON/OFF orientation.
3.1.2 DIP SWITCH S1 SETTINGS
DIP switch S1 is used to configure receive impedance, 
SWITCH S1 SUMMARY TABLE (factory defaults in bold)
| Position | Function | ON Position | OFF Position | 
| 
 | 
 | 
 | 
 | 
| RCV Impedance | 120 Ohm | 16 kOhm | |
| 
 | 
 | 
 | 
 | 
| 
 | 
 | 
 | 
 | 
| Echo Mode | Echo ON | Echo OFF | |
| 
 | 
 | 
 | 
 | 
*Note: Switches 
S1-1:  Receive Impedance
The setting for switch 
| Setting | |
| On | Low (120 Ohm) | 
| Off | High (16 kOhm typical) | 
S1-2  and S1-3:  2-wire/4-wire  Modes
Switches 
| Setting | ||
| On | On | |
| Off | Off | 
S1-4:  Echo Mode
The setting for switch 
| Setting | |
| On | Echo On | 
| Off | Echo Off | 
| 5 | 6 | 
