R&D Department
Testing Procedure
From PROEL R&D DEPT.
To PROEL SERVICE DEPT.
Object FLASH5A amplifier module - TESTING PROCEDURE
Date 30/04/2014
Instruments required:
1) Sinusoidal audio signal generator
2) 100MHz or more dual trace oscilloscope (scope)
3) True RMS digital multimeter (DMM) with dBu scale
4) 250W or more Variac transformer with 0-250 Vac range (230V european version)
or with 0-140 Vac range (120V US version)
5) 4 Ω 100W or more resistive load
6) 8 Ω 50W or more resistive load
7) Music and pink noise signal generator (CD player)
IMPORTANT: The oscilloscope must be insulated from the earth ground.
1. Set up
- Check the correct earth main connection on the rear surface of the front panel.
- Check the insulation between the heat sink and the case of IC4, IC5 and IC3.
- Set the LINE LEVEL control full clockwise.
- Set the NEARFIELD/MIDFIELD button in NEARFIELD position.
- Switch OFF the amplifier module.
2. Low amplifier check
- Connect the mains of amplifier module to VARIAC and set it at zero AC voltage.
- Connect the scope CH1 GND clip to P8 black wire/faston (GND), scope CH1 probe tip to P6 red wire/faston
(LOW OUT) and scope CH2 probe tip to P10 black wire/faston (HIGH OUT).
- Switch ON the amplifier module.
- Increase slowly the VARIAC voltage up to the nominal value (230Vac or 120Vac).
- Check the transformer secondary voltages with DMM (without signal on input):
52 ±2 Vac between red wire
32 ±2 Vac between yellow wire
- Using DMM check also the +15Vdc / -15Vdc supplies on relative voltage regulator outputs (IC4 & IC5
devices).
- Connect the signal generator to LINE INPUT (XLR/JACK socket) and set it at 100 Hz, -10 dBu.
- Verify that CH1 (LOW OUT) signal is 30V ±6 Vpp.
- Check of SIGNAL/LIMIT LED function, moving the volume potentiometer of the amplifier;
when the output signal is < 2 Vpp the led must be OFF
when the output signal is > 2 Vpp, the led must be GREEN.
- Rotate the volume potentiometer knob fully clockwise.
- Set the signal generator at 0 dBu.
- Connect the 4 Ω load resistor at LOW OUT and verify that the signal is symmetrical refer to GND, without
detectable distortion and oscillation.
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