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DISTRIBUTION AMPLIFIER/ZONE MIXER/MIC SPLITTER DA-410.
In the input stage, each one of the inputs has a jumper that lifts the input XLR ground. Next, the
signal crosses the input transformer (if the option is placed) and the switch LINE/MIC that allows to
choose the input gain (in line mode won't have gain, and in mic mode will have 12 dBu of gain).
Following the signal is electronically unbalanced and crosses the input level control. Note that the
input level detector reference signal is measured in two points. It's measured before and after the
input level control, in order to know if the input signal is overloaded before the DA-410 input or in the
input amplifier.
In the output stage, the signal crosses the input signal selector, that allow us to choose the input
signals A, B or both, for later carry out the input signals summing. Next it is the MONO switch that
adds the L and R output signals, and the output level control. Following the signal crosses the two
equaliser cards (if the options are placed), the electronic balanced output and the output transformer
(it the option is placed) and the output XLR connector. The output level detector reference signal is
measured in three points: A, B and C, the point A is located just after the input signal sum, the point B
after the output amplifier and the C point after the equaliser cards.
The monitor signal selector, take the output signal, just before the electronic balanced output,
allowing to listen the signal just in the output (either for the speakers or headphones), giving us a very
real signal reading. As seen in the block diagram, once selected the monitor signal, it crosses a level
control and a 10 dB amplifier driving the speakers (we could see in the block diagram, that when we
introduce a headphones jack, the signal in the speakers is muted).
9. REPAIR GUIDE
For service purposes, the unit must be open by removing the eight screws on the top cover.
NOTE:
This type of operations takes place with the unit open, for what it should be carried out by a
qualified technician.
DANGER:
Before opening the unit, disconnect it from the mains. It is important to indicate that
although the unit is power out (with the power switch in 0 position), if it continues connected to the
mains there are different parts of the unit that are subjected to high voltage.
CAUTION:
Protect the distribution amplifier from the rain and moisture, mainly if it is open. If liquid is
spilled into the unit, disconnect it from the mains and consult a qualified service technician.
Keep in mind that all the outputs are symmetrical, so when the section is identified, you could
interchange components, except for the circuits that are common to all the outputs as could be the
power supply, or the monitor signal selector.
We recommend a meticulous visual exam before beginning to change anything in the unit:
burnt resistors, potentiometers with a broken trace, etc. This exam many times gives us the key for the
problem, saving time and unnecessary efforts.
Keep in mind when removing an element of the main board, that it is double layer printed
circuit, and the components PADs goes joined from one layer to the other through a metal tube (VIA).
For that reason, avoid excessive overheating and strength that could pulled out the VIA. This is
important mainly in components having many pins (integrated circuits, connectors, etc.), for which it is
recommended to use a good desoldering station.
