QSC K8 Service Manual

3
TD-000487-00
K Series Service Manual
Table of Contents
1. Introduction ..................................................................................................................................................................................5
1.1 Restriction of Hazardous Substances Directive (RoHS) ...................................................................................................................................................... 5
1.2 Revision history ......................................................................................................................................................................................................................... 5
1.3 Service bulletins ........................................................................................................................................................................................................................ 5
1.4 Serial Numbers .......................................................................................................................................................................................................................... 5
1.5 The well-equipped service bench ........................................................................................................................................................................................... 6
2. Product specification and images ................................................................................................................................................7
3. Firmware .......................................................................................................................................................................................8
3.1 Firmware revisions and program numbers .......................................................................................................................................................................... 8
3.2 Firmware programming instructions ..................................................................................................................................................................................... 9
4. Operational description ............................................................................................................................................................. 11
4.1 Series description ..................................................................................................................................................................................................................... 11
4.2 Top-Box Models .......................................................................................................................................................................................................................11
4.3 KSub ..........................................................................................................................................................................................................................................12
4.4 Bucket of power (BOP) amplifier module............................................................................................................................................................................12
5. Top-box disassembly instructions .............................................................................................................................................. 15
5.1 Bucket of power .......................................................................................................................................................................................................................15
5.2 Front grille ................................................................................................................................................................................................................................16
5.3 Front baffle ...............................................................................................................................................................................................................................16
5.4 High frequency transducer.....................................................................................................................................................................................................17
5.5 Low frequency transducer .....................................................................................................................................................................................................18
5.6 Handles, feet, and pole mount ..............................................................................................................................................................................................18
6. KSub disassembly and repair procedures .................................................................................................................................20
6.1 Bucket of power ...................................................................................................................................................................................................................... 20
6.2 Low frequency transducers ................................................................................................................................................................................................... 20
6.3 Handles, threaded pole mount, and casters........................................................................................................................................................................21
7. BOP disassembly and repair procedures...................................................................................................................................23
7.1 Faceplate ................................................................................................................................................................................................................................... 23
7.2 PSU/amplifier board ............................................................................................................................................................................................................... 24
7.3 Input/DSP board...................................................................................................................................................................................................................... 25
7.4 Power inlet, power switch, and fan ...................................................................................................................................................................................... 25
8. Testing .........................................................................................................................................................................................26
8.1 Requirements .......................................................................................................................................................................................................................... 26
8.2 Bucket of power testing ......................................................................................................................................................................................................... 26
8.3 Loudspeaker testing ............................................................................................................................................................................................................... 29
9. Troubleshooting guide................................................................................................................................................................ 31
9.1 General tips and tricks.............................................................................................................................................................................................................31
9.2 Line filter - broken components (BOP) ............................................................................................................................................................................... 33
9.3 Broken capacitor C45 (BOP) ................................................................................................................................................................................................. 34
9.4 Input op-amp damage (BOP) ............................................................................................................................................................................................... 34
9.5 Amplifier section, MOSFET failure (BOP) ............................................................................................................................................................................ 35
9.6 Power supply, MOSFET failure (BOP) ................................................................................................................................................................................. 36
9.7 Fan behavior............................................................................................................................................................................................................................ 37
9.8 Internal wiring harness .......................................................................................................................................................................................................... 37
9.9 Front LED ................................................................................................................................................................................................................................. 38
9.10 Transducer issues .................................................................................................................................................................................................................. 39
9.11 Broken baffle ......................................................................................................................................................................................................................... 40
10. Service updates .......................................................................................................................................................................... 41
10.1 Inductor reinforcement, L13 .................................................................................................................................................................................................41
10.2 XLR combo jacks with locking tabs .....................................................................................................................................................................................41
11. Schematics and PCB images .......................................................................................................................................................42
11.1 Schematic with notes (all models) ...................................................................................................................................................................................... 42
11.2 PCB image with notes (all models) .................................................................................................................................................................................... 46
12. Component identification ..........................................................................................................................................................48
12.1 Top-box assembly components .......................................................................................................................................................................................... 48
12.2 KSub assembly components ............................................................................................................................................................................................... 49
12.3 BOP components .................................................................................................................................................................................................................. 50

QSC K8 Specifications

General

Product color	Black
LED indicators	Power, Signal strength, Stand-by
Housing material	Steel
Recommended usage	DJ
Suitable for outdoor use	-
Woofer	Yes
Speaker type	2-way
Number of drivers	1
Speaker placement	Floor
Audio output channels	1.0 channels
Woofer diameter (imperial)	8 \
Subwoofer driver diameter (imperial)	1.75 \
Impedance	40 Ω
Sensitivity	127 dB
Frequency range	61 - 20000 Hz
RMS rated power	1000 W
Peak Music Power Output (PMPO)	2000 W
Connectivity technology	Wired
AC input voltage	100 - 240 V
Power source type	AC
AC input frequency	50 - 60 Hz

Weight and Dimensions

Depth	269 mm
Width	280 mm
Height	450 mm
Weight	12200 g