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TOOLS AND EQUIPMENT REQUIRED
1. Multi-bit screwdriver set, M3, M4 & M17 Spanner and good quality hand tools.
2. A set of short medium bristled artist or horsehair brushes.
3. Methanol alcohol or a non-corrosive, non-lubricant solvent.
4. Digital multimeter with a 20 kHz bandwidth.
5. Audio signal generator.
6. Dual-trace oscilloscope.
7. Power supply board with a 60-watt series lamp on one socket, along with a shorting switch for the
lamp.
8. Variac 10KWA with AC voltage and current displays.
9. Analogue multi-meter with a sensitivity of minimum 20kΩ/V, and a maximum resistance scale of
10MΩ.
10. Resistive load – 4 Ohm 3000Watts Max (Qty. - 2)
2 Ohm 4000Watts Max (Qty. - 2)
8 Ohm 1500Watts Max (Qty. - 2)
It is advisable to use fine tip long meter probes and insulate the exposed metal of the probes with heatshrink
sleeving and leave only the tips exposed. This prevents accidental shorting while taking readings on any PCB.
If there is mains supply variation, with a Variac, you can adjust mains supply voltage going to
amplifier there by you can get correct power. An audio signal generator and an oscilloscope are required if the
waveform is to be monitored, and power measurements are to be made on an amplifier. They are also required
to check an amplifier where there is no apparent fault and no output either. However, all these methods are
recommended only for skilled technicians, experienced with class AB and class H amplifiers.
IMPORTANT NOTE:
This DJA series amplifier uses the latest technology in circuitry and fabrication.. If a technician attempting to
repair these amplifiers does not have extensive experience in working with PTH boards and SMT technology,
and with class AB/class H amplifier circuitry, it is strongly recommended that repairs at the component level
should not be attempted. In such a case, the technician should only attempt to identify the faulty module, and
replace it with a fresh module. The defective module should be sent back to Audioplus for repairs.
Even an experienced technician would be advised to work only on the power supply section of the amplifiers
that is if the fault exists in the bridge rectifiers, main filter condensers, regulated supplies or the mains
transformer. Attempting to work on the power amplifier module is fraught with danger, as to get access to the
components and to unsolder and solder the PCB; it is necessary to detach the PCB with the power transistors
and thermal sensor from the heatsink. In this condition it is impossible to power up the module without
damaging the power transistors, as there is no heatsink to remove the quiescent dissipation.
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