QSC PowerLight Series Operating manual

PowerLight™ Series
Two-ChannelPowerAmplifiers
TECHNICAL SERVICE MANUAL
*TD-000083-00*
TD-000083-00
Rev. Prelim.
▲▲
▲▲
▲PowerLight 6.0 II
▲▲
▲▲
▲PowerLight 6.0PFC
▲▲
▲▲
▲PowerLight 9.0PFC
ON
OFF
PROTECT
STANDBY
POWER
1 CHANNEL 2
9000 WATT POWER FACTOR CORRECTED PROFESSIONAL AMPLIFIER
22 22
32 32
24 24
26 26
28 28
30 30
-00 -00
20 20
18 18
14 14
88
dB
1 -CHANNEL- 2
dB
CLIP
-10dB
-20dB
SIGNAL
CLIP LIMITER
POWERLIGHT 9.0
PFC
HEARTHE POWER OFTECHNOLOGY.

TechnicalServiceManual 1
PowerLight6.0 II,PowerLight 6.0PFC,and PowerLight9.0PFC
QSC Audio Products, Inc.
Technical Services Group
Phone: 1-800QSCAUDIO(1-800-772-2834) USA only
[phone]
Fax: [phone]
Postal: 1665MacArthurBlvd.
CostaMesa, California 92626 USA
E-mail: [email protected]
Web: http://www.qscaudio.com(productinformationandsupport)
http://www.qscstore.com(partsandaccessorysales)
PowerLight Series
Technical Service Manual
Copyright 2004 QSC Audio Products, Inc. All rights reserved.
Document # TD-000083-00, Preliminary Rev. Released November 2004.
IMPORTANT NOTICE:
This document contains proprietary information that is the property
of QSC Audio Products, Inc, and may not be disclosed, reproduced or
used without express or written consent from QSC Audio Products.
▲▲
▲▲
▲PowerLight 6.0 II
▲▲
▲▲
▲PowerLight 6.0PFC
▲▲
▲▲
▲PowerLight 9.0PFC

2QSC Audio Products, Inc.
TD-000083-00
PowerLight 9.0PFC
PowerLight 6.0PFC
PowerLight 9.0 II

TechnicalServiceManual 3
PowerLight6.0 II,PowerLight 6.0PFC,and PowerLight9.0PFC
Table of Contents
PerformanceSpecifications ............................................................................................................................................................................................... 4
1. Introduction ..................................................................................................................................................................................................... 5
1.1Servicebulletins.............................................................................................................................................................................................................. 5
1.2The well-equipped servicebench ............................................................................................................................................................................... 5
1.3 Working with surface-mount components................................................................................................................................................................. 5
Two-terminalcomponents(resistors,capacitors,diodes,etc.)............................................................................................................................................................. 5
Multi-pincomponents(ICs,etc.) ........................................................................................................................................................................................................ 6
Three-terminalcomponents(transistors,etc.) .................................................................................................................................................................................... 6
1.4Series description ........................................................................................................................................................................................................... 6
1.5Technical descriptionsand theoryofoperation ........................................................................................................................................................ 7
Powersupplies ................................................................................................................................................................................................................................. 7
Audiocircuitry................................................................................................................................................................................................................................... 7
2. Servicing the amplifier.................................................................................................................................................................................. 8
2.1Mechanicaldisassemblyandreassembly ................................................................................................................................................................. 8
Introduction...................................................................................................................................................................................................................................... 8
Toolsandmaterialsneeded .............................................................................................................................................................................................................. 8
Disassembly ..................................................................................................................................................................................................................................... 8
Reassembly.................................................................................................................................................................................................................................... 11
2.2 The display board.......................................................................................................................................................................................................... 13
2.3AClinefilter ................................................................................................................................................................................................................... 13
2.4Powersupplyservicing................................................................................................................................................................................................ 15
Benchtestingpowersupplymodules .............................................................................................................................................................................................. 15
ReplacingswitchingMOSFETsinPFCmodels.................................................................................................................................................................................. 15
Suggestionsfortroubleshooting..................................................................................................................................................................................................... 17
Adjustingandcalibratingthepowersupplymodule......................................................................................................................................................................... 18
2.5ACvoltageconversions................................................................................................................................................................................................ 22
2.6Biasadjustments ........................................................................................................................................................................................................... 22
3. Troubleshooting............................................................................................................................................................................................ 23
3.1Initialcheck ................................................................................................................................................................................................................... 23
3.2Preliminarytroubleshooting........................................................................................................................................................................................ 23
3.3Furthertroubleshooting ................................................................................................................................................................................................ 24
4. Parts ................................................................................................................................................................................................................. 25
4.1 Semiconductor package descriptions and pinouts ................................................................................................................................................ 25
4.2Partslists ........................................................................................................................................................................................................................ 33
ChassisAssembly(QSCpart#WP-000268-00) ................................................................................................................................................................................ 33
ChassisAssembly(QSCpart#WP-000268-02) ............................................................................................................................................................................... 34
ChassisAssembly(QSCpart#WP-000260-00) ............................................................................................................................................................................... 35
ChassisAssembly(QSCpart#WP-000260-02) ............................................................................................................................................................................... 36
ChassisAssembly(QSCpart#WP-000170-00) ............................................................................................................................................................................... 37
ChassisAssembly(QSCpart#WP-000170-02) ............................................................................................................................................................................... 38
ChassisAssembly,Rear(QSCpart#WP-000271-00)....................................................................................................................................................................... 39
ChassisAssembly,Rear(QSCpart#WP-000264-00)....................................................................................................................................................................... 39
ChassisAssembly,Rear(QSCPart#WP-000172-00)....................................................................................................................................................................... 40
OutputPCBAssembly(QSCpart#WP-000179-00) ......................................................................................................................................................................... 40
InputPCBAssembly(QSCpart#WP-000272-00)............................................................................................................................................................................ 40
InputPCBAssembly(QSCpart#WP-000265-00)............................................................................................................................................................................ 41
InputPCBAssembly(QSCpart#WP-000175-00)............................................................................................................................................................................ 41
InputDaughterboardAssembly(QSCpart#WP-000178-00)........................................................................................................................................................... 42
AudioChannelModuleAssembly(QSCpart numberWP-000276-00)............................................................................................................................................. 42
AudioChannelModuleAssembly(QSCpart#WP-000182-00) ....................................................................................................................................................... 46
PowerSupplyAssembly(QSCpart#WP-000266-00)...................................................................................................................................................................... 50
PowerSupplyAssembly(QSCpart#WP-000266-02)...................................................................................................................................................................... 52
PowerSupplyAssembly(QSCpart#WP-000262-00)...................................................................................................................................................................... 55
PowerSupplyAssembly(QSCpart#WP-000262-02)...................................................................................................................................................................... 56
PowerSupplyControllerAssembly(QSCpart#WP-000263-00)...................................................................................................................................................... 58
PowerSupplyAssembly(QSCpart#WP-000173-00)...................................................................................................................................................................... 60
PowerSupplyAssembly(QSCpart#WP-000180-00)...................................................................................................................................................................... 61
PowerSupplyControllerAssembly(QSCpart#WP-000174-00)...................................................................................................................................................... 63
DisplayPCBAssembly(QSCpartnumberWP-000176-00)............................................................................................................................................................... 64
LineFilterAssembly(QSCpartnumberWP-000177-00)................................................................................................................................................................... 66
LineFilterAssembly(QSCpartnumberWP-000181-00)................................................................................................................................................................... 66
MatchedFETs................................................................................................................................................................................................................................. 67
5. Schematic diagrams .................................................................................................................................................................................... 68

4QSC Audio Products, Inc.
TD-000083-00
PowerLight6.0II PowerLight6.0PFC PowerLight9.0PFC
OUTPUT POWER in watts
FTC: 20 Hz–20 kHz, both channels driven
8Ωper channel 1150 (< 0.1% THD) 1400 (< 0.1% THD) 1800 (< 0.2% THD)
4Ωper channel 2050 (< 0.1% THD) 2500 (< 0.1% THD) 3200 (< 0.2% THD)
2Ωper channel 3250 (< 0.1% THD) 3250 (< 0.1% THD)
EIA: 1 kHz @ 1% THD, both channels driven
8Ωper channel 1300 1600 1950
4Ωper channel 2200 2800 3400
2Ωper channel 3500 3500 4500
Bridge Mono:
16Ω,1kHz,1%THD 2600 3200 3900
8Ω, 1 kHz, 1% THD 4400 5600 6800
4Ω, 1 kHz, 1% THD 7000 7000 9000
DYNAMIC HEADROOM 0.77 dB @ 4Ω
DISTORTION
THD: 20 Hz–20 kHz (8, 4, & 2Ω@ 10 dB below rated power) < 0.06% < 0.15%
(8 & 4Ω@ FTC rated power) < 0.1% (20 Hz–20 kHz) < 0.02% (20 Hz–2 kHz) < 0.03% (20 Hz–2 kHz)
20 Hz–2 kHz (2Ω)< 0.1% (20 Hz–20 kHz @ 3250 W) < 0.02% (@ 3250 W) < 0.05% (@ 4500 W)
SMPTE-IM: < 0.02% < 0.02% < 0.02%
FREQUENCY RESPONSE 20 Hz–20 kHz, ±0.15 dB
(at 10 dB below rated output power) -3 dB points: 2 Hz and 50 kHz
DAMPING FACTOR > 2000 @ 8Ω, at 1 kHz and below
NOISE (unweighted 20 Hz to 20 kHz, below rated output) 107 dB 107 dB 107 dB
VOLTAGE GAIN 40× (32 dB)
INPUT SENSITIVITY, V RMS
full rated power @ 8Ω2.4 v (+9.8 dBu) 2.6 v (+10.6 dBu) 3.0 v (+11.8 dBu)
full rated power @ 4Ω2.3 v (+9.5 dBu) 2.5 v (+10.2 dBu) 3.8 v (+11.2 dBu)
INPUT IMPEDANCE 10 kΩunbalanced
20 kΩbalanced
CONTROLS Front:ACswitch,Ch.1andCh. 2 gain, Ch. 1 and Ch. 2cliplimiterswitches
Rear: Parallel/Stereo/Bridge switch, remote power supply enable terminals
INDICATORS each channel PROTECT: Red LED CLIP: Red LED
STANDBY: Yellow LED -10 dB: Yellow LED
POWER: Green LED -20 dB: Yellow LED
SIGNAL: Green LED
CONNECTORS Input: Active balanced; “Euro-style” terminal block; Neutrik “Combo” XLR
and¼"(6.3mm)TRS,tipand pin 2 positive
Output: “Touch-Proof” binding posts (60A rated) and Neutrik Speakon™ (1 per channel)
DataPort: HD 15 female connector for use with QSControl, Basis, or accessories
COOLING Four continuously variable speed fans, back-to-front air flow
AMPLIFIER PROTECTION Fullshort circuit, opencircuit,thermal,ultrasonic, andRFprotection
Stable into reactive or mismatched loads
LOAD PROTECTION Turn-on/turn-off muting,
OUTPUT CIRCUIT TYPE H:Full-bridgecurrentcellvertical N-channel MOSFET linearoutputwithClassH4-stephigh efficiency circuit
DIMENSIONS 19.0"(48.3cm)wide,3.5"(8.9cm)tall(2rackspaces)
17.9"(45.5cm)rackmounting to rear support ears; 19.5”(49.5cm)overall
WEIGHT Shipping: 59lb.(26.8kg) 65lb.(29.5kg) 65lb.(29.5kg)
Net: 53lb.(24.1kg) 59lb.(26.8kg) 59lb.(26.8kg)
POWER REQUIREMENTS Available for 120 or 220–240 VAC, 50/60 Hz
POWER CONSUMPTION @ 120 VAC
(both channels driven)
Multiply currents by 0.5 for 230V units
1Pinknoise at 1/8 of full power; analogous to typicalprogramwithoccasionalclipping.
2Pinknoise at 1/3 of full power;analogousto typical program with heavy clipping.
3Continuous sine wave at threshold of clipping (1% THD). US patents pending
SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
PerformanceSpecifications
Idle Typical1Full2Max3
8Ω2.5 A 10.3 A 19.3 A 39.3 A
4Ω2.5 A 15.5 A 35.1 A 67.5 A
2Ω2.5 A 23.8 A 47.4 A 104.7 A
Idle Typical
1
Full
2
Max
3
8Ω 2.5 A 10.3 A 19.3 A 39.3 A
4Ω 2.5 A 15.5 A 35.1 A 67.5 A
2Ω 2.5 A 23.8 A 47.4 A 104.7 A
Idle Typical1Full2Max3
8Ω 2.5 A 10.3 A 19.3 A 39.3 A
4Ω 2.5 A 15.5 A 35.1 A 67.5 A
2Ω 2.5 A 23.8 A 47.4 A 104.7 A

TechnicalServiceManual 5
PowerLight6.0 II,PowerLight 6.0PFC,and PowerLight9.0PFC
Solder braid
1. Introduction
1.3 Working with surface-mount
components
PowerLight amplifiers, like many modern electronic products, use
surface-mount technology (SMT) components where appropriate in
order to make high-density circuitry that is reliable and economical
to manufacture.
SMT components in the PowerLight amps are used in the small-
signal and control circuits, so they do not handle significant
amounts of power; therefore, they are subject to very little stress
and should seldom fail. Sometimes they do fail, or they require
replacement for a performance upgrade or modification. Thus, it is
important to know how to work with SMT components.
Specialized tools and equipment exist for soldering, unsoldering,
and removing SMT components quickly and efficiently, but they are
often expensive. Most SMT repairs, though, can be handled reason-
ably well with common tools and equipment, such as tweezers,
solder braid, and fine-tip soldering irons.
Two-terminalcomponents(resistors,capacitors,
diodes, etc.)
Removal
1. Use two soldering irons, prefer-
ably about 25 to 40 watts, with
fine tips.
2. With a soldering iron in each
hand, hold one tip on the solder at
one end of the component and the
other tip on the other end (Figure
1.1).
3. Once the solder melts on both
ends, grip the component
between the two tips and lift it
from the circuit board.
4. Use solder braid and a soldering
iron to remove the solder from the
two pads (Figure 1.2).
Insertion
1. With a soldering iron and 60/40 or 63/37 eutectic-type solder,
melt just enough solder onto one pad to create a small mound
(Figure 1.3).
2. Grasp the component in the middle with tweezers. Melt the
small mound of solder with the iron and place the component
across the two pads (in the correct orientation, if the compo-
nent is sensitive to direction) and press it flat against the circuit
board, with one end of the component immersed in the melted
solder (Figure 1.4).
3. Hold the component in place and take the soldering iron away.
1.1 Service bulletins
Contact QSC Technical Services to make sure you have the most
up-to-date service bulletins for PowerLight Series amplifiers.
Service bulletins may be distributed in hard copy, via fax, and
electronically (Adobe Acrobat PDF) via CD-ROMs, FTP from the QSC
web site (www.qscaudio.com), and e-mail.
These service bulletins had been issued at the time this manual
was printed: PFC0001, “PFC MOSFET Replacement” (PowerLight
6.0PFC and PowerLight 9.0PFC only); PFC0002, “PFC Power Supply
Replacement Guidelines” (PowerLight 6.0PFC and PowerLight 9.0PFC
only); and PFC0003, “Amplifier Goes Into Protect When Turned On”
(all three models).
1.2 The well-equipped service
bench
To properly service QSC amplifiers, a technician needs the right
tools. The technician’s service bench should have the following
equipment:
• Digital multimeter with RMS AC voltage and current
• Digital clamp-on ammeter
• Dual-trace oscilloscope
• Audio distortion analyzer
• Non-inductive load resistors, configurable as 8 ohms (min. 1800
watts capacity), as 4 ohms (min. 3200 watts capacity), and as
2 ohms (min. 4500 watts capacity)
• Variable AC voltage source, such as a Variac or Powerstat
variable transformer, with a rated current capacity of up to 50A
(for 120V models) or 25A (for 230V models)
• Low-distortion audio sine wave generator
• Philips and flat screwdrivers
• Soldering iron with a fine tip (25–60W recommended)
• Rosin-core solder (60/40 or 63/37)
• Long-nose pliers
• Diagonal cutters
• Wire strippers
Automated test equipment, such as an Audio Precision worksta-
tion, is very useful for servicing PowerLight amplifiers. Contact
QSC Technical Services to obtain applicable AP test files.
Servicing power supply modules will require some additional
special-built equipment:
• Power supply remote controller
• PFC power supply fixture (for PFC modules only)
• CMP box
Becauseof the complexity of the PFC power supplies, QSC
recommends they be serviced only by QSC.
Figure1.1.
Figure1.2.

6QSC Audio Products, Inc.
TD-000083-00
Solder
Solder
Tweezers
Solder
Let the solder harden to tack the
component in place.
4. Fully solder the other end of the
component to its pad. Let the
solder harden (Figure 1.5).
5. Fully solder the tacked end of
the component to its pad (Figure
1.6).
Three-terminal
components(transistors,
etc.)
Removal
1. With a soldering iron and solder
braid, remove as much solder as
possible from the middle
terminal of the component.
2. With a soldering iron in each
hand, hold one tip on the solder
at the terminal at one end of the
component and the other tip on
the terminal at the other end.
3. When the solder on both ends
melts, grip the component between the two tips and lift it from
the circuit board. You might need to quickly touch the pad on
the middle terminal with a soldering iron to melt any remaining
solder that might be holding the component down.
4. Use solder braid and a soldering iron to remove the solder from
the three pads.
Insertion
1. With a soldering iron and 60/40 or 63/37 eutectic-type solder,
melt just enough solder onto one pad to create a small mound
of solder.
2. Grasp the component with tweezers. Melt the small mound of
solder with the iron and place the component in the correct
orientation across the three pads and press it flat against the
circuit board, with one terminal of the component pressed into
the melted solder.
3. Hold the component in place and take the soldering iron away.
Let the solder harden to tack the component in place.
4. Fully solder the other terminals of the component to their pads.
Let the solder harden.
5. Fully solder the tacked terminal of the component to its pad.
Multi-pincomponents(ICs,etc.)
Removal
Removing a multi-pin SMT component is a delicate procedure.
Ideally, you should use a soldering iron with an attachment that
allows you to heat all the pins simultaneously.
If such a soldering device is not available, use this procedure:
1. Use a soldering iron and solder braid to remove as much solder
as possible from the pins of the component.
2. With fine tweezers, carefully try to lift each pin to see if it’s
free. If it’s not, touch it with the tip of the soldering iron and if
necessary, use the solder braid to remove the remaining solder.
3. Repeat the process until all the pins are free and you can
remove the component.
Insertion
1. With a soldering iron and 60/40 or 63/37 eutectic-type solder,
melt just enough solder onto one pad to create a small mound
of solder. It is usually easiest to use a pad that corresponds to
one of the end or corner pins of the component.
2. Grasp the component with tweezers. Melt the small mound of
solder with the iron and place the component in the correct
orientation upon its pads and gently press it flat against the
circuit board, with the appropriate terminal of the component
pressed into the melted solder.
3. Hold the component in place and take the soldering iron away.
Let the solder harden to tack the component in place.
4. Fully solder the other terminals of the component to their pads.
Let the solder harden.
5. Fully solder the tacked terminal of the component to its pad.
1.4 Series description
QSC’s PowerLight Series amplifiers are high-performance
professional audio products, designed primarily for live and touring
sound and large-scale installations.
This service manual covers the three most powerful models
developed for the PowerLight Series: the PowerLight 6.0 II, the
PowerLight 6.0PFC, and the PowerLight 9.0PFC. Each one has two
audio channels and is three rack spaces tall. See page 2 for
complete specifications.
The PowerLight 6.0PFC and PowerLight 9.0PFC feature power
supplies with power factor correction, which reduces peak current
demand by drawing power throughout the AC voltage waveform.
The PowerLight 6.0 II has power supplies that don’t have PFC but
are simpler and less expensive to manufacture.
The first four digits of the amplifier’s serial number indicate the
month and year of manufacture in MMYY formay. For example,
0701xxxxx = July 2001). A serial number that starts with “13”
indicates the amplifier was made during the model’s beta
production. The PowerLight 9.0PFC entered production in May 1998.
The PowerLight 6.0PFC followed in March 1999, and the
PowerLight 6.0 II, in August 2002. Many PowerLight 6.0PFC
amplifiers, however, have been converted by QSC Technical
Services into PowerLight 6.0 II amplifiers, so you may encounter
PowerLight 6.0 II amplifiers with serial number date codes that
precede the model’s actual release date.
The PowerLight 6.0PFC and PowerLight 9.0PFC ceased production in
March 2004.
Figure1.3.
Figure1.4.
Figure1.5.
Figure1.6.

Technical Service Manual 7
PowerLight 6.0 II, PowerLight 6.0PFC, and PowerLight 9.0PFC
1.5 Technical descriptions and
theory of operation
Powersupplies
QSC PowerLight amplifiers feature high-frequency switch-mode
power supplies that help reduce noise, increase electrical
efficiency, and lower weight. Two models, the PowerLight 9.0PFC
and the PowerLight 6.0PFC, had power factor correction to reduce
the peak current demand from
the AC mains. They accom-
plished this by drawing current
throughout the AC voltage
waveform, instead of just at
the peaks, as most amplifiers
and other electronic equipment
do. The PowerLight 6.0 II was
developed later, and its power
supplies do not have power
factor correction.
All three models have a four-
tier class H system of multiple
rail voltages to boost efficiency.
A power amplifier is most efficient at or near full power, yet the
dynamic nature of music and other typical audio requires much less
than full power most of the time. Thus, this class H scheme creates
essentially four different “full-power” levels within the amplifier
channel. The amplifier circuitry
automatically and instanta-
neously switches to the lowest
rail voltage that will allow the
reproduction of the audio
signal without discontinuity.
Each amplifier channel has its
own power supply. In addition,
each has a small “housekeep-
ing” supply that manages the
turn-on functions before the
main power supply starts up.
Audiocircuitry
The audio inputs are balanced to offer a high amount of common-
mode noise rejection. The input balancing is done using an
instrumentation amplifier arrangement, which uses a single op
amp, arranged as a voltage follower or buffer, on each leg of the
balanced input, driving a single op amp differential amplifier. The
degree of common-mode rejection is dependent on the close
matching of the impedance between each leg and ground and
around the differential amplifier. The circuitry uses 1% precision
resistors to ensure at least 40 dB of common-mode rejection.
The differential amplifier circuitry includes a first-order high-
frequency roll-off, down 3 dB at 280 kHz (nearly four octaves above
the high end of the audio spectrum). This makes the amplifier less
susceptible to RF interference,
high-frequency oscillations, etc.
The audio signal passes through
a pre-clipper, which prevents
the audio signal from driving
the output section itself into
actual clipping. This maintains
damping on the channel output
even during clipping so that it
continues to tightly control the
loudspeaker motion, which is
something most amplifiers
cannot do. A defeatable clip
limiter on each channel reduces
signal level when clipping occurs; it does not prevent clipping, but
reduces the amount of distortion to inaudible or barely audible
levels.
An all-pass filter uses group delay to slow the audio signal by 4 µs,
but the class H steps are controlled by the undelayed signal. This
reduces IM distortion by ensuring that the steps are executed
before the audio signal in the output section reaches the transition
thresholds.
The audio signal voltage is converted into current by transistors
Q87 and Q89, to be precisely bifurcated into positive and negative
halves by the current steering circuitry. These current signals are
the controls for the output devices.The output devices are vertical
MOSFETs, which are commonly
used for very high power
switching because of their
power handling capability and
general nonlinearity. Using
them for linear audio amplifica-
tion requires an unorthodox
approach. In these three
PowerLight amplifier models,
each channel has eight MOSFET
devices arranged in a full bridge
configuration. Each one has a
local management circuit called
a current cell that controls and
linearizes the device by
providing the necessary
compensation to make the
MOSFET’s conductivity track the
signal current.
Figure 1.7. Amplifiers without
PFC draw current only at the
peaks of the AC voltage
waveform.
Figure 1.8. An amplifier with PFC
draws current throughout the
AC voltage waveform.
Figure 1.10. Most amps lose
feedback during clipping,
resulting in loss of damping and
in “clip sticking.”
Figure 1.9. The rail voltages of
the output section switch
among four tiers to reproduce
the signal faithfully while
maximizing efficiency.
Figure 1.11. The pre-clipping
scheme in the PowerLight 6.0
PFC
,
9.0
PFC
, and 6.0 II keeps the
output signal clean despite the
flat-topping of the waveform.

8QSC Audio Products, Inc.
TD-000083-00
2. Servicing the amplifier
2.1 Mechanical disassembly and reassembly
Key QSC Part Description Qty.
1
2
3
4
5
WP-000170-XX Chassis assy., PL 9.0 1
CH-000079-00 Top cover 1
SC-082051-PL Screw, #8-32 × 5/16”, pan head 6
SC-080051-PU Screw, #8-32 × 5/16”, flat head 12
PL-000104-00 Insulator, high volt. 2
Introduction
Replacing components will usually require removing the affected
modules from the amplifier chassis. The two channels each have
their own power supply module and audio module, and they share
the line filter assembly and the input, output, and display board
assemblies.
Within the chassis, the power supply modules are on the bottom,
and the audio modules are on top. Getting at a power supply
module requires removal of its audio module first.
The following instructions describe the procedure for removing
both audio and both power supply modules. However, if you only
need to work on one channel, you do not need to remove the
modules from the other.
Tools and materials needed
• Philips screwdriver
• Diagonal cutters
• Tie wraps
• Needle-nose pliers
• Adhesive rubber foot (one per channel), QSC part # QQ-
QQQQQQ-QQorequivalent
• 5/64”hex(Allen) key
• 11/32” nutdriver or socket wrench
• Isopropyl alcohol and a small brush
Disassembly
Removing the top cover
1. Disconnect the amplifier from AC power and allow at least 10
minutes for internal voltages to bleed down.
2. A total of 18 screws—six with pan heads and twelve with flat
heads—hold the top cover to the chassis. Using a Philips
screwdriver, remove them and set them aside. See Figure 2.1.
3. Lift the top cover up at the front until it clears the side rack ear
pieces, then lift it off the chassis. If the front of the cover is
bent or dented, make sure the front edge clears the two
display board headers.
Figure 2.1. Removing or installing
the top cover.

TechnicalServiceManual 9
PowerLight6.0 II,PowerLight 6.0PFC,and PowerLight9.0PFC
Fan (4-pin header;
2 pins per fan)
Power supply
(wires 0 through 4)
Housekeeping
supply
Display
board
(via multi-
conductor
ribbon cable)
From input
board
(detachable
latching header)
(2 bundles)
Preparing the audio modules for removal
4. There are two fishpaper insulators on each audio module.
Remove them by lifting them straight up off the heat sinks. Do
not slide them forward or backward.
5. Cut the tie wraps in the seven locations shown in Figure 2.2.
6. Disconnect the display board header in front of each module.
7. Using needle-nose pliers, grasp one of the housekeeping
supply connectors and disconnect it from the modules (see
Figure X.X). Repeat for the other(s).
8. Disconnect the fan connections (two on each module).
9. Spread open the latches on the power
supply control interface connections and
disconnect the headers from the
modules.
10. Remove the two screws that secure the
audio module to the chassis partition.
One screw is at the corner near the
power supply connections, and the other
is about 6 cm (2.5 inches) behind the
housekeeping supply connections.
11. Locate the power supply connections, the
five screw terminals at the front of each
module. Loosen them and remove the
wires.
12. There may be an adhesive rubber foot
wedged in front of each module circuit board.
Grasp it with the needle-nose pliers and pull
it out.
Removing the chassis rear panel
13. Remove the four screws on the rear panel
(see Figure 2.4).
14. Tip the amplifier up on its right side (the side
opposite the power cord). There are three flat
head screws in a line along the center of the
side panel. Remove them.
15. Remove the two pan head screws on the rear
rack tab.
16. Set the amp back down and remove the two
pan head screws from the other rear rack tab.
17. Remove the two screws under the power
cord.
18. Tip the chassis rear panel back and discon-
nect the header from the input board.
19. Lift the fan wires clear of the heat sinks on
the audio modules.
Power supply
control (8-pin
header)
Figure 2.2. Seven tie wraps.
Figure 2.3. The connections to
the audio module.

10 QSC Audio Products, Inc.
TD-000083-00
Key QSC Part Description Qty.
1
2
3
4
5
CH-000078-00 Chassis, PL 9.0 1
WP-000172-00 Rear chassis assembly 1
SC-082051-PL Screw, #8 × 5/16”, pan head 4
SC-080051-PU Screw, #8-32 × 5/16”, flat head 4
SC-082051-PL Screw, #8 × 5/16”, pan head 2
20. Remove the chassis rear panel from the main chassis.
21. Cut and remove the tie wraps that secure the output wires to
the rear panel.
Removing the audio modules
22. There is a ground screw at the back of each audio module
(see Figure 2.4). Remove it.
23. Slide the audio module toward the front of the chassis so that
its keyed mounting holes are clear of the standoffs.
24. Lift up the back of the audio module slightly, then lift the
entire module clear of the chassis.
Removing the power supply modules
25. If you need to remove one or both power supply modules, you
will need to remove both audio modules. Invert one audio
module and set it on top of the other channel’s audio module,
then set them aside.
26. Straighten the five power supply wires on each channel.
27. Remove the three screws from the front of the chassis
partition.
28. Remove the side-facing screw from the front of the partition
on channel 1’s side.
29. Remove two black pan head screws from the center line of
the chassis partition.
30. Slide the chassis partition back, then lift up on the channel 2
side of it. Press down on the back of the partition, then lift it
clear of the chassis.
31. Remove the two screws at the front of the power supply
module.
32. Use a 5/64” hex (Allen) key to remove the screw at the rear of
the power supply module.
33. Use an 11/32” nutdriver or socket wrench to remove the two
nuts on the AC connection (a white and a black wire).
34. Slide the power supply module toward the rear of the chassis,
then lift it up and out of the amplifier.
Inspectingthepower supply modules
35. Visually inspect the power supply module. Check the leads of
diodes D1 and D12, because they sometimes crack due to
flexing of the circuit board.
36. Using isopropyl alcohol and a brush, clean any dirty or charred
parts of the circuit board. Look for burned-off circuit board
traces, especially around the switching MOSFETs; missing or
damaged ones can be repaired using a trace repair kit. If the
Locations of
ground screws
for audio modules
Figure 2.4. Removing or installing the
chassis rear panel.

TechnicalServiceManual 11
PowerLight6.0 II,PowerLight 6.0PFC,and PowerLight9.0PFC
Key QSC Part Description Qty.
1
2
3
4
5
8
CH-000078-00 Chassis, PL 9.0 1
PL-000107-00 Heatsink insulator 2
CH-000080-00 Chassis horiz. partition 1
SC-080051-PS Screw, #8-32 × 5/16”, SEMS 3
PL-000109-00 Insulator, mega platform 2
PL-000137-00 2
6
7
SC-082051-PU Screw, #8-32 × 5/16”, pan head 3
SC-060042-PP Screw, #6-32 × 1/4”, SEMS 3
Insulator, amp rear bottom
circuit board is burned into the fiber layers or badly damaged,
replace the entire module.
See instructions for servicing the power supply module
elsewhere in this chapter.
Reassembly
Reassembling the amplifier chassis is essentially reversing the
order of the disassembly process.
Installingthepowersupplymodule
1. Align the keyed slots in the power supply module circuit board
with the chassis standoffs. Watch out for the fish paper
insulators, which may get caught underneath. Drop the
module into place on the standoffs and slide it forward.
2. Using the 11/32” nutdriver or socket wrench, attach the AC
wires to the module. The black wire attaches in front (closer
to the front of the amplifier chassis) of the white one.
3. Using the 5/64” hex (Allen) key, insert and tighten the screw
at the rear of the power supply module.
4. Insert and tighten the two screws at the front of the module.
5. Install the chassis partition.
6. Insert and tighten the two screws along the center line of the
chassis partition.
7. Insert and tighten the side-facing screw at the front of the
chassis partition on the channel 1 side.
8. Insert and tighten the three screws at the front of the chassis
partition.
Installingtheaudiomodules
9. Place the audio modules in position.
10. Insert and tighten the ground screw at the back of each
module (see Figure 2.4).
11. With new tie wraps, secure the output wires to the chassis
rear panel.
12. Loosely insert one screw on each end of the chassis rear
panel, then tighten them both.
13. Insert and tighten the other two screws.
Figure 2.5. Removing or installing the chassis partition.

12 QSC Audio Products, Inc.
TD-000083-00
Key QSC Part Description Qty.
1
2
3
4
5
CH-000078-00 Chassis, PL 9.0 1
WP-000173-00 Power supply PCB assy. (120V) 2
WP-000180-00
SC-040155-00 Screw, #4-40 shoulder hex head 2
SC-060042-PP Screw, #6-32 × 1/4”, SEMS 4
NW-080500-KP Keps nut, #8-32 4
Power supply PCB assy. (230V) 2
14. Insert and tighten the two screws under the power cord.
15. On each audio module, tuck the two fan wires into one or two
slots of the heat sink. Reconnect both to the four-pin header
on the audio module.
16. Reconnect the input headers to the audio module.
17. Tip the amplifier up on its right side (the side opposite the
power cord). Insert and tighten the three flat head screws in a
line along the center of the side panel.
18. Set the amp back down. Reconnect the five power supply
wires, 0 through 4, to their respective screw terminals at the
front of the module. Make sure they are placed in the proper
sequence—from left to right, as viewed from the front of the
amplifier:.0, 1, 2, 3, and 4.
19. Reconnect the power supply control interface. Make sure the
latching wings of the board-mounted connector are up all the
way.
20. Reconnect the housekeeping supply wires at the front of the
module.
21. Using five new tie wraps, secure the wire bundles to the
chassis partition at or near the front of the amplifier. Each
secures one bundle, except for the one at the center, which
secures two.
22. Using two new tie wraps, re-connect and secure the two
headers to the display board.
23. Re-install the top cover of the amplifier.
Figure 2.6. Removing or installing the
power supply modules.

TechnicalServiceManual 13
PowerLight6.0 II,PowerLight 6.0PFC,and PowerLight9.0PFC
Key QSC Part Description Qty.
1
2
3
4
5
6
CH-000078-00 Chassis, PL 9.0 1
HW-000079-00 Hex standoff #6-32 x 9/16” 5
WP-000176-00 Display PCB assy. 1
SC-060042-PP Screw, #6-32 × 1/4”, SEMS 2
HW-060080-HW Hex standoff #6-32 x 1/2” 3
PL-000054-00 Knob fab. 2
2.2 The display board
The display board contains the signal metering, clip, power, and
status LEDs. It also holds the two gain potentiometers. LED failures
are very rare, but you will need to remove the board if the gain
pots become damaged or badly contaminated. See Figure 2.7.
2.3 AC line filter
The AC line filter is an important part of the amplifier because it
reduces noise and interference from the internal switching
circuitry to prevent its radiation into the AC wiring. It also contains
part of the housekeeping supplies for the two audio modules;
without the housekeeping supplies, the amplifier’s power supply
modules will not start up even if they are in working order.
The line filters are the same among the three amplifier models,
but the 120-volt and 230-volt versions are not interchangeable.
See Figure 2.8.
Figure 5.7. Removing or installing the display board.

14 QSC Audio Products, Inc.
TD-000083-00
Key QSC Part Description Qty.
1
2
3
4
WP-000177-00 Line filter PCB assy. 1
NW-000021-03 Flat Washer 1
WP-000042-00 AC power cord assy., 30A 125V 1
SW-000027-SW Switch AC 1
Key QSC Part Description Qty.
1
2
3
4
5
WP-000181-00 Line filter PCB assy. (230V) 1
C0-000099-00 Connector line side flange 1
SC-083061-PU Screw, #8-18 × 3/8”, flat head 2
SW-000027-SW Switch AC 1
WC-000022-00 Cord set 3 cond. 16A 250 VAC 1
120V version
230V version
Figure 2.8. Assembly details of the AC line filter.

Technical Service Manual 15
PowerLight 6.0 II, PowerLight 6.0PFC, and PowerLight 9.0PFC
2.4 Power supply servicing
Bench testing power supply modules
The housekeeping supplies provide electrical power to certain
control circuitry in their respective audio channel modules. The
control circuitry in turn enables the power supply module to
operate. Thus, a power supply module normally will not operate
when it is not connected to an audio channel.
The remote control circuit shown in Figure 2.9 allows the power
supply module to operate without an audio channel module
connected. This is useful for verifying the power supply’s operation
independently of other amplifier circuitry.
Partslist
• 8-pin header (J1)
• 9-volt battery (B1)
• SPST switch (S1)
• Three-lead tri-color LED (LD1)
• 18 kΩresistor (R1)
• Two 1.5 kΩresistors (R2 and R3)
ecnerefertraP #trapweN noitpircseD #trapdlosecalper… noitpircseD ?sledomhcihW
4Q&,3Q,2Q,1Q 00-881000-DQ TEFSOMA5505N55FXI 00-911000-DQTEFSOMA8405N84FXI
sledomllA
8R&,7R,6R,5R 01-10574.-ER 57.4 ΩΩ
Ω
ΩΩ rotsiserttaw-¼ 01-20001.-ER1Ωrotsiserttaw-¼
sledomllA
8D&,7D,2D,1D 00-381000-DQ edoid80SPE06 00-621000-DQedoidA60-06IESD
ylnosledomV021
8D&,7D,2D,1D 00-281000-DQ edoid21SPE06 00-761000-DQedoid21-06IESD
ylnosledomV032
02C 00-900014-AC roticapacV052Fµ1.0 00-004743-ACroticapacV004Fµ740.0
sledomllA
Replacementparts
Replacing switching MOSFETs in PFC models
Replacing the power MOSFETs and their associated components
requires that the power supply modules be removed from the
amplifier.
Tools and materials required:
• Soldering iron
• Rosin-core solder (60/40 or 63/37 eutectic type)
• Long-nose pliers
• #1 and #2 Philips screwdrivers
• Thermal grease (heat sink compound)
• Small diagonal cutters
• Desoldering equipment or solder braid
• Micro-torque wrench with 9/64” Allen (hex) and #1 Philips bits
If fuse F1 on the power supply module’s printed circuit board (PCB)
is blown, you will also need a 1A 250V 5×20 mm slow-blow fuse
(QSC part # MS-000113-00) to replace it with. Also, the alumina
insulator between the diodes and the heat sink is very fragile and
often breaks when the diodes are removed; replace it with QSC
part # PL-000085-00.
To ensure that the devices will share power equally, the four
MOSFETs must have similar VDSS. For a set of four matched
MOSFETs, as pre-sorted by QSC production, order QSC part #
WP-000056-00.
Procedure: replacing Q1, Q2, Q3, and Q4
1. Remove the heat sink assembly to which the MOSFETs are
attached.
To do this, remove the clamps on the four diodes (D1, D2, D7,
and D8) to free them from the heat sink. Keep the two mica
insulators (from between the
diodes and clamps) and set
them aside for when you
reassemble the heat sink and
diodes later; they are fragile,
so be careful handling them
but replace any that are
damaged. The QSC part
number is PL-000059-00.
Remove the alumina insulator
Figure 2.10. Bottom view of a
MOSFET
THIS REMOTE CONTROL IS USED TO TURN ON THE
PFC POWER SUPPLY VIA J100 ON THE CONTROLLER
BOARD.
CLOSING POWER SWITCH S1 ENABLES THE POWER
SUPPLY, AND LED LD1:2 WILL GLOW GREEN.
LED1:1 WILL ALSO LIGHT, AND THE RESULTING
COLOR WILL BE YELLOW-ORANGE.
WHEN
THE AC INPUT VOLTAGE APPLIED TO THE PS
MODULE REACHES THE TURN-ON THRESHOLD (65
VAC FOR 120V UNIT OR 130 VAC FOR 230V UNIT),
POWER SUPPLY
CONTROLLER BOARD
POWER SUPPLY TEST
REMOTE CONTROLLER
Figure 2.9. Remote controller for power supply testing.

16 QSC Audio Products, Inc.
TD-000083-00
(from between the diodes and the heat sink); it is extremely
fragile, so it is best to replace it during reassembly with a
new one.
Then remove the 16 screws that attach the MOSFETs to the
printed circuit board (PCB); if the MOSFETs are blown, some
of the mounting screws may be melted or damaged. The new
MOSFETs come with new mounting screws with captive
washers, so there is no need to save old ones for reuse.
Remove the other four mounting screws so that the heat sink
assembly is free from the circuit board. Set the hardware
aside.
Find where the twisted wire lead from the heat sink’s thermal
sensor attaches to a pair of pins on the board, and unplug it.
Detach the gate drive cable, which is an 8-conductor ribbon
cable that plugs into an 8-pin header. Lift the heat sink and
MOSFET assembly from the board. If the strip of fishpaper
(Figure 2.11) remains stuck to the PCB, leave it there; if it
comes loose, set it aside for re-assembly later.
2. Remove the MOSFETs from the heat sink. Thoroughly clean the
old thermal grease off the heat sink. Apply fresh thermal
grease to the new MOSFETs (QSC part # QD-000188-00) and
attach them to the heat sink.
Make sure the new MOSFETs are correctly oriented. One end
of each MOSFET has a mounting hole, while the other has an
open-ended slot (see Figure 2.9). Each MOSFET must be
mounted so the slot end faces
away from the diode end of the
heat sink (see Figure 5.11). Try to get the MOSFETs evenly
spaced and as close to perfectly in line as you can. The silk
screen print on the circuit board (see Figure 5.12) shows the
correct orientation.
Tighten the MOSFET mounting screws to 32–35 lb-in (3.6–4.0
N-m) torque. Do not over-torque them.
3. Remove the four diodes on the circuit board (D1, D2, D7, and
D8). See Figure 2.12.
4. Check the value and rating labeled on capacitor C20 (see
Figure 2.13). If it is not a 0.1 µF 250V capacitor (early modules
will have the original 0.047 µF 400V component instead),
replace it with QSC part # CA-410009-00.
5. Remove resistors R5 through R8 (see Figure 2.11) and replace
them with 4.75Ω¼-watt resistors (QSC part # RE-.47501-10).
6. Set the MOSFET and heat sink assembly upside-down and
place the PCB on top of it. Make sure all the threaded holes in
the heat sink and the MOSFETs line up exactly with the holes
in the board. If any MOSFETs don’t line up, reposition them so
they do because misaligned mounting screws can damage
them when tightened.
Make sure the fishpaper strip is in place, and then reattach
the MOSFET and heat sink assembly to the PCB. Make sure
you use the correct screws and washers in each location.
Tighten the four heat sink screws to 32–35 lb-in (3.6–4.0 N-m)
torque and the MOSFET mounting screws to 12 lb-in (1.4 N-
m). Do not over-torque them.
CAUTION: Overtightening its mounting screws will destroy a
MOSFET. When tightening a screw, use the split lockwasher
as a visual guide; as soon as it is flattened, the screw is tight
enough.
Plug the thermal sensor lead onto its two pins on the circuit
board.
7. Clear any solder from the circuit board holes for the four diodes.
Apply a thin coating of new thermal grease to both sides of
the alumina strip and set it in place on the heat sink.
Insert the four new diodes (120V models: QSC part #
QD-000183-00; 230V models: QSC part # QD-000182-00) into
their holes in the PCB, but do not solder them in place yet.
Then set the two mica insulators in place over the diodes
(they will overlap in the middle), and clamp and fasten the
diodes to the heat sink; tighten the screws to 32–35 lb-in
(3.6–4.0 N-m) torque. Do not over-torque them. As you do
Figure 2.10: The heat sink assembly, with all four MOSFETs
attached. The “diode” end of the heat sink is at right; the slots in
the MOSFETs would face to the left.
Figure 2.11. The silk screen on the circuit board shows the
correct orientation of the MOSFETs. This photo also shows
the four resistors (R5–R8) to be replaced.
“Diode”
end of
heatsink

TechnicalServiceManual 17
PowerLight6.0 II,PowerLight 6.0PFC,and PowerLight9.0PFC
this, make sure the diodes are straight and evenly spaced, and
reposition them if necessary.
8. Solder the four diodes to the circuit board.
9. Reattach the gate drive cable.
10. Check the fuse (see Figure 2.14). If it is blown, replace it with
a slow-blow 1A 250V 5×20 mm fuse (QSC part #
MS-000113-00).
11. Repeat the procedure for the other channel’s power supply
board if it also has failed or is to be updated.
Suggestionsfortroubleshooting
If you are repairing a failed power supply module and not simply
upgrading a working one, you should determine whether other
components have also failed.
Typical collateral failures around PFC power supply module failures
include:
Blown high rail diodes: Check D12 and D14 for sooty or
blackened thermal grease around their edges or for any other
signs of damage. If you suspect that they might be damaged,
remove them from the circuit board and check them with the
diode test function on a DMM. Replace them if necessary
(QSC part # QD-000126-00). These diodes are clamped onto
the other heat sink, at the end next to the power transformer.
If you remove the diodes, thoroughly clean away the old
thermal grease from that portion of the heat sink and from
the mica insulators; apply fresh thermal grease when you
reassemble or replace them.
Blown driver ICs: The two MIC4452BN MOSFET driver ICs, U1
and U3, are under the MOSFET heat sink. Frequently, when
MOSFETs fail, the driver IC associated with the transistor(s)
fails, too. The IC’s QSC part # is IC-000064-00.
Fuses: Conditions that cause the MOSFETs to fail also frequently
cause the fuses on the AC line filter to blow. The filter circuit
board runs along the side of the amplifier between the AC power
cable and the AC power switch. Each channel has two fast-blow
ceramic AC fuses, for a total of four (120V models: 125V 25A,
QSC part # MS-000112-00; 230V models: 250V 15A, QSC part #
MS-150250-FU). Check them and replace any that are blown.
Also on the AC line filter board are the housekeeping supplies
for each channel; if they do not work, the channels will not
start even if the power supply modules are in perfect working
order. The housekeeping supplies each use a 250V 1A slow-
blow fuse (QSC part # MS-000113-00).
FuseF1
CapacitorC20
Figure 2.12. These four diodes need to be replaced.
Figure 2.13. Capacitor C20 may also need
replacement. See the text.
Figure 2.14. Fuse F1 may need replacing.

18 QSC Audio Products, Inc.
TD-000083-00
Adjustingandcalibratingthepowersupply
module
Adjusting and calibrating the power supply card will help ensure
the success of the repair; this portion of the service bulletin
describes a series of five procedures for doing so. Because of the
specialized nature of the power supply fixture required for these
procedures, it can only be performed at the QSC factory by trained
personnel. Follow these procedures exactly and in order.
There are four trimpots, VR1–VR4 (see Figure 2.14), on the
controller card that must be adjusted correctly before reinstalling
the power supply in the amplifier:
VR1 On the PL 9.0PFC, this trimpot sets VOUT/32; on the PL 6.0PFC, it
sets VOUT/26.6.
VR2 This trimpot is for balancing the transformer to the PFC circuitry.
VR3 This trimpot sets the maximum 2-ohm output power. For the
PL 9.0PFC, it will be set for 4500 watts @ 2 ohms at 2 kHz; for
the PL 6.0PFC, it will be set for 3600 watts @ 2 ohms at 2 kHz.
VR4 This trimpot sets the power supply’s idle voltage. For the PL
9.0PFC, it will be set for 191.3 volts DC; for the PL 6.0PFC it will
be 166.5 volts DC.
Tools and materials needed:
• PFC power supply fixture with external power supply and CMP
(Control-Monitor-Power) box
• Two digital multimeters (DMM #1 and #2) with clip-on leads
• Digital multimeter (DMM #3) with clamp-on AC current probe
• 0–240 VAC Variac™, Powerstat™, or similar variable AC
transformer; 60 amperes or higher rating, with RMS voltage
and current metering
• 120 VAC power (for the fixture’s housekeeping supply)
• Four-channel oscilloscope with ×1/×10 probes
• Oscilloscope with differential probe (optional; see
step 10 of the V
OUT
procedure)
• Small pocket-type flat-blade screwdriver
• Grounded anti-static work surface
• Audio Precision (AP) workstation with PFC test
procedure files* and 2-ohm load resistor banks
(mimimum power handling capacity: 1250 watts per
8-ohm resistor; 5000 watts total in 2-ohm configura-
tion).
*The four AP test procedure files are available on the QSC Technical
Support CD-ROM: Pfcxf.tst; Pfcpwr2k.tst; Pfcpwr20.tst; and
Pfctherm.tst.
The PFC power supply fixture
The PFC power supply fixture is a special test bed for PowerLight 6.0
and 9.0 supply modules. It has the necessary connections and
indicators for adjusting, calibrating, and testing the modules. It
also contains one audio channel of a PowerLight 9.0 to allow
testing of the module’s capability to power an actual amplifier
channel. The fixture is custom built by QSC.
Front panel switches and indicators
From left to right (Figure 2.14):
•Power switch. For the AC lines to the power supply module
being tested.
•Power indicator. It lights when the fixture is connected to AC
power and is turned on.
•Blown fuse indicator. Connected across the large fuse under
the door in the top of the fixture chassis, this indicator will light
if the fuse blows. The fuse, however, is merely a backup in case
the CMP box’s solid-state electronic fuse malfunctions.
•Protect, Standby, and Power indicators. In the portions of
the test that use the amplifier channel, these LEDs function just
as they do on a regular amplifier.
•Fan switch. Some portions of these procedures require the
module fans running, and others need them off.
•“Set VOUT” switch. This switch is used for the first procedure.
•“ISET” switch. This switch also is used in the first procedure
for checking the module’s ISET circuit.
•“ISET” indicator. This tri-color LED indicates the status of the
module’s ISET circuit.
Rear panel switches and attachments
From left to right (Figure 2.15):
•Audio input. This is where to connect the signal output from
the AP workstation.
•DC high rail outputs. These are two pairs of red and black
binding posts, and they carry the DC output of the supply
module’s high rails. Connect DMM #1 to one of these sets of
binding posts.
•Audio output. This Neutrik Speakon connector carries the
audio output of the fixture’s amplifier channel. Connect this
VR1
VR2
VR3
VR4
Figure 2.16. The front of the fixture. The amplifier channel’s gain control is
to the right, out of the picture
Figure 2.15. The locations of the four trimpots, VR1–VR4