1
TEST PROCEDURE MODEL – AMC+60
1.
Perform physical inspection (Visual Inspection stage).
1.1
Check:
•
All screws for tightness (esp. transistor bolts),
•
Capacitors for polarity,
•
Earth connection for good contact (XLR GND to AC earth),
•
Power transistors for shorts to heatsink,
•
All wiring points for good contacts (soldering and crimping)
PRETESTING
PRE TESTING SETUP REQUIREMENT
a
Oscilloscope.
b
Variac.
c
Multimeter.
d
Load [4
Ω
]
e
Signal generator.
2.
Set up amplifier for test (Pretesting stage).
2.1.
Check
•
AC fuses (2A), 20mm HRC
•
DC fuses (8A), 20mm HRC
2.2.
Connect amplifier to:
•
Variac (0Vac),
•
Signal generator (mic1, no signal),
•
Resistive load ( 4
Ω
on 4
Ω
terminal ).
2.3.
Reset controls:
•
Volume controls to minimum,
•
Bass/treble control to center,
•
PR1 (presets) Amplifier PCB fully clockwise.
3.
Power up
3.1
Turn on power switch and adjust voltage to 230VAC. Watch current meter for excess current
draw. Current should not exceed 0.5A.
3.2
Check DC power supply at fuses. Should be approx. +49V (
±
1.5V)
3.4 Check DC voltage on mixer board. Should be approx. 12V(
±
0.5V)
3.5
Check 1/2 VCC on mixer board should be 5.4 VDC (
±
0.5)
3.6
Measure DC voltages on IC of mixer & input PCB's, p8 12V (+5%), p4 0V (+100mV), p1 5.4V
(
±
5%).
3.7
Put a multimeter across R32 the meter read 0mV then slowly adjust the preset PR1 so that you get 4mV
+ 5mV. Check Quiescent Vtg across all Emitter resistors.
4.
AC Check
4.1
Set signal generator to 1mV. Turn up Mic1 volume control to full. Watch for irregularities with output.
4.2
Set output to 7V using master volume control. Check voltage across Emitter resistors (on power
devices)