Instruction manual

UAM4SYS • 35
(mute) button. The reading should be 0VDC with the button
pressed and +5VDC when not pressed. If this is not the case
check all connections and components between pin 4(12) and
the push button for opens, shorts and incorrect installation.
3. If only the loudness (mute) LED does not turn on and off but the
functions operate properly go to step 5.
4. While measuring the voltage at U5 pin 6(10) press the loudness
(mute) pushbutton one time.
Note that the voltage on pins 7(9) and 3(13) MUST be
opposite the voltage on pin 6(10).
The voltage should change state to either +5VDC or 0VDC. If it
does change check all connections and components between
U5 pins 6(10) and the LED for opens or shorts and proper
installation and values. If it does not change go to step …….
5. While measuring the voltage at U5 pins 7(9) and/or 3(13), (they
MUST be the same voltage), press the loudness (mute)
pushbutton one time. The voltage should change it’s state to
either +5VDC or 0VDC. If it does not change go to step 6. If it
does change check all connections and components between
U5 pins 7(9) and 3(13) and the LED for opens or shorts and
proper installation and values. Note that pins 7(9) and 3(13)
MUST be the same voltage
6. Measure the voltage at U5 pins 7(9) and/or 3(13). [READING =
+5VDC or 0VDC] If the reading is +5VDC and the LED is not
on go to step 7.
7. If the LED is not on measure the voltage on both sides of R28
(R22). If both readings are 5VDC check all connections
between D3(D1) and R28(R22). If the LED is still not on the
LED may be defective or installed wrong.
POWER AMPLIFIER OUTPUT SECTION
The power amplifier section of your UAM4SYS was preassembled and tested
at the factory but there is a possibility you may have problems with it’s
operation. If you think there is a problem we suggest you first make sure you
have installed and configured headers H3, H4 and H5 properly and there are
no solder bridges in those areas. Also make sure the 18 volt power supply
jumper between location JP1 and JP2 is installed. If you are using the
UAM4SYS in single channel mono mode make sure you have installed the
jumpers between “L+” and “R+” and “L-“ and “R-“ correctly, H3 is installed and
you are applying the input signal to the RIGHT input channel. Other than the
surface mounted capacitors and resistors there is nothing else you can repair
without specialized soldering equipment. Any attempt to repair this section