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.