Amplifier Test And Calibration; Power Consumption - Mackie 406M Service Manual
Ppm series
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Also See for 406M:
- Specifications (6 pages) ,
- Hook-up manual (7 pages) ,
- Owner's manual (36 pages)
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Amplifier tests for the 808M and 808S
Power Consumption
With no signal and no load, the power consumption from the AC mains should be:
Variac
Up to 40vac
Up to 60vac
Up to 120vac
DC supplies
Set the Variac up to 120vac (US models)
Measure the DC supplies: (see page 193-5 for the pcb layout)
+96 to +98vdc
–96 to –98vdc
+86 to +89vdc
–86 to –89vdc
+42 to +44vdc
–42 to –44vdc
+14.5 to +16.5vdc U1 Pin 3
–14.5 to –16.5vdc U2 Pin 3
+4.75 to +5.25vdc U7 Pins 2 & 3
Bias Adjustment
The bias adjustment is best done when the amplifier has been warmed up. Run it with a music
program into a dummy load until the heatsink is warm to the touch.
The actual adjustment is done with no signal and no load:
Channel 1
Measure the DC voltage between J23 & J24
Adjust R7 for 18 to 20mvdc,
Seal the pot with a drop of nail paint
Channel 2
Measure the DC voltage between J21 & J22
Adjust R6 for 18 to 20mvdc
Seal the pot with a drop of nail paint
Power Tests
Continuous Sine Wave Average Output Power, both channels driven (rated power):
340 watts per channel into 4Ω from 40Hz to 20kHz, with no more than 0.15% THD
240 watts per channel into 8Ω from 40Hz to 20kHz, with no more than 0.10% THD
Check for symmetrical clipping and correct operation of the DC rail switching.
Ch.2 NPN
Ch.2 Bias pot R6
Q9
Q10
Q2
Q1
Q3
b c e
b c e
e c b
e c b
Q78
Q74
Test
Q68
Q69
points
Measure
Bias Ch. 2
Ch.2 PNP
14
This is the 193 amplifier circuit board, see chapter 193 for more details
Power consumption
< 5W
< 20W
< 50W
@pcb test point +100v
@pcb test point -100v
@pcb test point +90v
@pcb test point -90v
@pcb test point +45v
@pcb test point -45v
DC Rail
test points
90 Volt rect.
+15V
-15V
FET
Reg
Reg
Q11
Q7
D1
U1
U2
b c e
e c b
D100
U7
TH1
Q75
Q70
+5V
FET
Reg
45 Volt rect.
Ch.1 NPN
FET
D4
Q12
Q13
Q8
D2
b c e
b c e
e c b
e c b
D101
Q76
Q71
Q72
D99
FET
Ch.1 PNP
Ch.1 Bias pot R7
Q14
Q5
Q4
Q6
b c e
e c b
Q79
Q77
Test
Q73
points
Measure
Bias Ch. 1
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