Internal Jumper Settings for Custom Installation
(see figure 1)
There are internal jumpers that can be used to disable the front panel level controls, to select one of two input sensitivity settings, and to engage the special Parallel Mono mode for driving low impedance speaker combinations in custom installations.
WARNING: Removing the top cover of the am- plifier to access the jumpers may expose you to potentially dangerous voltages. These set- tings should only be made by a qualified tech- nician. The AC power cord must be removed from the amplifier before the top cover is re- moved.
After removing the top cover, the jumper blocks can be found on the circuit board as shown in Figure 1. Each jumper block has a printed identification number. The function, ID num- bers, and settings for each jumper block are provided below. To change the setting, place the jumper on the appropriate pins as indi- cated.
Bypassing the Variable Level Controls (S603 and S604)
The front panel Level Controls allow you to adjust the input gain for each channel of the amplifier. These level controls can by bypassed by changing the jumper position on jumper blocks S603 (for CH 1) and S604 (for CH2).
To disable the variable level controls:
place a jumper across pins 2 and 3 on jumper block S603 and across pins 1 and 2 on jumper block S604.
To enable the variable level controls:
place a jumper across pins 1 and 2 on jumper block S603 and across pins 2 and 3 on jumper block S604.
10
Input Sensitivity
(S605 and S606)
Jumper blocks S605 and S606 are used to set the input sensitivity of the amplifier.
For high sensitivity (0.775v input for
rated power): place the jumpers across pins 1 and 2 on jumper blocks S605 and S606.
For low sensitivity (1.5v input for rated
power): place the jumpers across pins 2 and 3 on jumper blocks S605 and S606.
Selecting Parallel Mono Mode (S602 and P1/P3)
As described earlier in this manual, the two most common operating configurations for the
The third configuration, Parallel Mono mode, allows both channels of the amplifier to be com- bined in parallel. This mode is useful for driv- ing a low impedance speaker load such as driving multiple speakers in a custom instal- lation.
This Parallel Mono mode can be selected only by setting internal jumpers (jumper block S602) and changing a buss wire connection (con- nectors P1and P2).
NOTE: it is essential that Parallel Mono mode not be engaged at the same time as Stereo mode. This will blow the internal rail fuses. Make sure that you follow all of the instruc- tions below carefully.
To convert to Parallel Mono mode:
1.Place the jumper across pins 1 and 2 on jumper block S602.
2.Locate the buss wire linking the P2 connector to the P3 connector. Remove the wire from P3 and move it to the adjacent P1 connector. For Parallel Mono mode, the buss wire must link P2 to P1.
To return to normal configuration (Ste- reo or Bridged Mono modes):
1.Place the jumper across pins 2 and 3 on jumper block S602.
2.Locate the buss wire linking the P2 connector to the P1 connector. Remove the wire from P1 and move it to the adjacent P3 connector. For normal mode, the buss wire must link P2 to P3.
Troubleshooting
Most difficulties in audio systems are the re- sult of poor or wrong connections, or improper control settings. If you encounter problems, isolate the area of the difficulty, check the control settings, determine the cause of the fault and make the necessary changes. If you are un- able to get sound from the
Front Panel Power Indicator Is Not Lit
No main power to the
No Sound
If the amp is getting AC power, but is producing no sound, check the PROTECTION INDICA- TORS on the front panel. If lit, see below. If not, check all of your connections and con- trol settings on associated components. Make sure that your input connections and speaker connections match your selected stereo/mono configuration.
Protection Indicator Is Lit
The front panel PROTECTION INDICATORS light when the
