NKI1480B DAX60 and DAX120 Amplifiers—Installation
Page 11 of 18 (Jul-98)
Service Information
Do not attempt to service your amplifiers unless you are an authorized technician.
Important:
T
he information that follows is intended for qualified service technicians only
Locating the Test Points
Whenever possible, take the voltage readings on the large connector on the main
printed circuit board. You will have to remove the front cover to access it.
The DAX6O has a single 16-pin connector labeled "T” on the schematic; the pins
are numbered from bottom to top on the board.
The DAX12O has two 16-pin connectors: the top connector and the top half of the
bottom connector are referred to as "J1" on the schematic, and the rest of the
bottom connector is referred to as "J2" on the schematic. The pins are numbered 1-
24 and 1-8, from top to bottom on the board.
Measuring DC Voltages
DC voltages are printed in rectangular boxes at various points on the schematic.
When measuring these voltages on the amplifier, use a DC meter with a resistance
of 1 megohm per volt and proceed as follows:
Step 1. Place the amplifier on a suitable work surface and make sure that no signal
is present at the input terminals. Disconnect the speakers and connect a suitable
resistive load in their place:
DAX6O: The load should have at least a 60-watt power rating and a value of 10.4
ohms across the 25-volt output or 83.3 ohms across the 70.7-volt output.
DAX12O: The load should have at least a 120-watt power rating and a value of 5.2
ohms across the 25-volt output or 41.6 ohms across the 70.7-volt output.
Step 2. Plug the amplifier into a 12Q-VAC, 60-Hz source.
Step 3. On the DAX6O: Connect the meter's negative lead to the amplifier common
at Connector “T-14." As you locate each DC voltage on the schematic, note the
number of the nearest "T" terminal in that leg of the circuit and, if possible, take the
readings between such a "T" terminal and “T-14."
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