QSC Audio Musical Instrument UF 3 User Guide

                
                 
                  
                   
                
                 
                  
                  
                   
                    
                     
                     
                      
                
                 
                 
                  
                  
                   
UF-3  
Universal  
Filter  
*TD-004031-00*  
*TD-004031-00*  
Rev. A  
 
UF-3 UNIVERSAL FILTER  
I. DESCRIPTION  
TheUF-3isanembeddeddual-channeluniversalfilteraccessoryforusewithselectQSCpoweramplifiers.Compatibleamplifiermodelsandlines,  
both current and discontinued, include:  
All PLX, two-channel CX, and two-channel DCA models (with a BSC-3 or BSC-5 BusCard installed)  
All four-channel CX and DCA models (with a BSC-7 BusCard installed)  
PowerLight models PL 1.0, PL 1.0HV, PL 1.4, PL 1.5X, PL 1.6HVX, PL 1.8, and PL 2.0HV (with a BSC-2 or BSC-4 BusCard installed)  
PowerLight models PL 3.4, PL 3.8X, and PL 4.0 (with a BSC-6 BusCard installed)  
All MXa models (MX 1000a, MX 1500a, MX 2000a, and MX 3000a; Note: does not include MX 700), which use Level 1 Open Input  
Architecture  
All EX models (EX 800, EX 1250, EX 2500, and EX 4000), which use Level 2 Open Input Architecture  
Legacy CX models CX6, CX6T, CX12, and CX12T, which use Level 1 Open Input Architecture  
UsingtheUF-3asadefaultcrossoverorEQisidealforrentalsoundsystems,sinceitvirtuallyeliminatesthepossibilityofunauthorizedtampering  
with settings or other such user errors.  
Physically, the UF-3 is a small circuit card that mounts inside the amplifier. Older amplifier models that use Open Input Architecture have a two-  
section row of 22 solder holes called a Mini Sloton their input boards. This is where the UF-3 is installed. The input board is part of the  
removeable input module, so the UF-3 can be installed without opening the amplifier chassis or even without removing the amplifier from an  
equipment rack.  
TheUF-3performsthesamefunctionsastheolderUF-2accessorydoes,butonasmaller,morecompactcircuitboardthatcanfitinmoreamplifier  
models, such as the PowerLight 3.4, 3.8X, or 4.0. To fit in these models, the circuit board has a pre-scored breakaway section.  
Newer models such as the PowerLight, PLX, DCA and CX series require the installation of an appropriate BusCard in order to provide a slot for  
the UF-3. Depending on the amplifier model, a BusCard can provide as many as four slots for accessory cards. Each slot is equivalent to the Mini  
Slotof the older amplifiersOpen Input Architecture. For ease of installation, it is best to mount the UF-3 to the BusCard before installing the  
BusCard itself inside the amplifier.  
Theinstallationprocessinvolvessoldering, soonlyqualifiedtechnicalpersonsshouldattempttoinstalltheUF-3;ideally, youshouldenlistQSCs  
TechnicalServicesdepartmentoranauthorizedservicecentertoperformthetask.Theinstallationsectionofthismanualoffersmoreinformation  
about installing the UF-3.  
II. FEATURES  
The UF-3 allows independent filtering of the two audio channels. You can select high-pass, low-pass, or bandpass filtering, as well as the  
frequencies of the filtering.  
Either channels circuitry contains electronically balanced input circuitry and bypassable low-pass and high-pass circuitry. Each filter circuit has  
a four-pole (24 dB/  
octave)Linkwitz-Riley  
Low-Pass Filter Bypass  
High-Pass Filter Bypass  
alignment. Figure 1  
shows a block dia-  
gram of the UF-3.  
(+) Input  
(-) Input  
Optional  
CD Horn  
Boost  
Programmable  
Linkwitz-Riley  
High-Pass Filter  
Programmable  
Linkwitz-Riley  
Low-Pass Filter  
1
2
1
2
Input  
Differential  
Amplifier  
Channel  
Output  
3
3
3-pin  
jumper block  
3-pin  
jumper block  
Figure 1—Block diagram of UF-3 (1 of 2 channels shown)  
1
 
III. PROGRAMMING THE UF-3  
The UF-3 circuit board has six 3-pin headers and four SIP resistor network sockets (see Figure 2). All are used for programming the module. The  
circuitryforthetwochannelsisidentical,sotheheadersandsocketsaredividedbetweenthem:thosedesignatedbyathree-digitnumberstarting  
in a 1(headers J101, J102, and J103; and SIP resistor network sockets RN102 and RN104) are for Channel 1, while those with a three-digit  
number starting in a 2are for Channel 2. The following instructions will use an xin place of the first digit, except where a specific channel  
reference is necessary.  
Channel 1  
Channel 2  
Notes on Stereo, Bridged, or Parallel  
Operation  
1
2
3
1
2
3
(low-pass bypass/enable) J101  
J102 (high-pass bypass/enable)  
(low-pass bypass/enable) J202  
(CD horn EQ) J203  
J201 (high-pass bypass/enable)  
1
2
3
1
2
3
Except for specialized bi-amp models such as the  
PowerLight 1.5X, 1.6HVX, or 3.8X, the amplifier in which the  
UF-3 is installed has a switch for setting the operating  
mode of the amplifier, i.e., stereo, parallel mono, or  
bridged mono. In the signal flow, the UF-3 accessory is  
located after the switch, so you must configure both  
channelsoftheUF-3accordingly, whatevertheoperating  
mode. Usually you would use identical settings on both  
J103(CD horn EQ)  
RN102  
RN104  
RN204  
RN202  
(f of low-pass filter)  
(f of high-pass filter)  
(f of low-pass filter)  
(f of high-pass filter)  
Figure 2UF-3 Circuit board jumper and resistor network locations  
1
2
3
channels in stereo or parallel mode, depending on the application. If the amplifier is in bridged mode, bypass  
Channel 2 of the UF-3 and use the Channel 1 input and processing only.  
Pins 1 & 2  
shorted together  
Bypassing the Filtering  
1
2
3
Pins 2 & 3  
shorted together  
To completely bypass the filtering circuitry of a channel, set the jumpers on both Jx01 and Jx02 across pins 1 and  
2, which are the upper two pins on their headers (see Figure 3). Note: If you neglect to place jumpers on either  
header, no signal will pass on that channel.  
1
2
3
Figure 3Jumper positions  
Frequency  
(Hz)  
SIP resistor  
network value  
80  
100  
120K  
82K  
68K  
56K  
47K  
33K  
18K  
12K  
8.2K  
6.8K  
5.6K  
4.7K  
3.3K  
1.8K  
1.2K  
560  
Programming the Low-Pass Filter  
120  
To use the low-pass filter, set the jumper on Jx01 across pins 2 and 3, which are the lower two pins on  
their header. If, however, you do not wish to use the low-pass filter and want to bypass it instead, set the  
jumper across pins 1 and 2.  
160  
200  
250  
Tosetthecornerfrequency(atwhichtheoutputis6dBdown)ofthelow-passfilter,choosetheappropriate  
value for RNx02; use the table at left.  
500  
800  
If there is a resistor network already installed in the socket, carefully pull it straight out. Insert the pins  
of the new resistor network into the socket holes and carefully press the network into the socket. Be  
careful to avoid bending the pins of the resistor network. Orientation of the resistor network is  
unimportant, as long as all eight pins are well seated in the socket.  
1000  
1200  
1600  
2000  
2500  
5000  
8000  
16000  
20000  
470  
2
 
Programming the High-Pass Filter and CD Horn Equalization  
Frequency  
(Hz)  
SIP resistor  
network value  
To use either the high-pass filter or the constant-directivity horn equalization, or both, set the jumper on  
Jx02 across pins 2 and 3, which are the lower two pins on their header. If, however, you do not wish to  
use either one and want to bypass them instead, set the jumper across pins 1 and 2.  
20  
30  
120K  
82K  
56K  
47K  
27K  
22K  
20K  
15K  
12K  
8.2K  
5.6K  
4.7K  
2.7K  
2.2K  
2.0K  
1.5K  
1.2K  
560  
To set the corner frequency (at which the output is 6 dB down) of the high-pass filter, choose the  
appropriate value for RNx04; use the table at right.  
40  
50  
If there is a resistor network already installed in the socket, carefully pull it straight out. Insert the pins  
of the new resistor network into the socket holes and carefully press the network into the socket. Be  
careful to avoid bending the pins of the resistor network. Orientation of the resistor network is  
unimportant, as long as all eight pins are well seated in the socket.  
80  
100  
120  
150  
200  
300  
400  
500  
800  
1000  
1200  
1500  
2000  
4000  
5000  
8000  
In addition to enabling the high-pass filter at Jx02, if you opt for CD horn equalization you must place a  
jumper at Jx03 as well. The UF-3 offers two equalization curves for CD horn correction: one with +6 dB  
of boost at 20 kHz (place the jumper across pins 1 and 2 of Jx03), and one with +10 dB of boost at 20 kHz  
(place the jumper across pins 2 and 3). If you do not place a jumper in one position or the other, the CD  
horn equalization circuit will be inactive.  
The table below is a summary of jumper settings for the UF-3; similar information is printed on the  
breakaway section of the UF-3s circuit board. Figure 4 shows how to identify the SIP resistor values.  
Pins 1 & 2 Pins 2 & 3  
None  
Function  
Bypass low-pass  
Header  
J101  
J101  
J102  
J102  
J103  
J103  
J103  
J201  
J201  
J202  
J202  
J203  
J203  
J203  
470  
X
X
X
X
270  
Enable low-pass  
Bypass high-pass  
Channel 1: Enable high-pass  
Disable CD horn boost  
X
CD horn boost, +6 dB @ 20 kHz  
X
X
X
X
X
X
CD horn boost, +10 dB @ 20 kHz  
Bypass low-pass  
Enable low-pass  
Bypass high-pass  
Channel 2: Enable high-pass  
Disable CD horn boost  
X
CD horn boost, +6 dB @ 20 kHz  
CD horn boost, +10 dB @ 20 kHz  
X
X
3
 
RESISTANCE CODE  
270 271  
470 471  
560 561  
1.2K 122  
1.5K 152  
1.8K 182  
2.0K 202  
2.2K 222  
2.7K 272  
3.3K 332  
4.7K 472  
5.6K 562  
6.8K 682  
8.2K 822  
12K 123  
15K 153  
18K 183  
20K 203  
22K 223  
27K 273  
33K 333  
47K 473  
56K 563  
68K 683  
82K 823  
120K 124  
Use only these three digits to  
determine resistance code.  
Disregard the other  
numerals and letters.  
Figure 4SIP resistor network  
identification  
IV. TYPICAL APPLICATIONS  
Subsonic Filter  
Subsonic filters are commonly used in sound installations to filter out rumbles and other inaudible or unwanted low frequency signals and to  
protect speaker drivers. Vented speaker enclosures in particular often exhibit a phenomenon in which the acoustical damping on the driver(s)  
drops at extremely low frequencies below their own resonant frequency. In a situation like this, a  
subsonic filter will help to prevent damage from over-excursion of the speaker cone.  
Program settings:  
Typ. 20–50 Hz  
1. Set the jumper on Jx01 to bypass the low-pass filter (across pins 1 and 2).  
Subsonic roll-off  
2. Set the jumper on Jx02 to enable the high-pass filter (across pins 2 and 3).  
3. No jumper on Jx03.  
Figure 5UF-3 as a subsonic filter  
4. Insert a resistor network in RNx04 that is appropriate to the desired roll-off frequencytypically 20, 30, 40, or 50 Hz.  
4
 
Ultrasonic Filter  
An ultrasonic filter is useful for minimizing RF interference, oscillations, leakage or aliasing from digital devices, and other signals that are too  
high in pitch to hear but may wreak havoc in an amplifier system.  
Program settings:  
Typ. 1620 kHz  
1. Set the jumper on Jx01 to enable the low-pass filter (across pins 2 and 3).  
2. Set the jumper on Jx02 to bypass the high-pass filter (across pins 1 and 2).  
Ultrasonic roll-off  
3. Insert a resistor network in RNx02 that is appropriate to the desired roll-off frequency—  
typically 16 or 20 kHz.  
Figure 6UF-2 as an ultrasonic filter  
Bandpass Filter  
Abandpassfiltermaybeusefulifthespeakersystemdrivenbytheamplifierhasalimitedbandwidth.Minimizingtheout-of-the-passbandenergy  
may result in reduced distortion and better intelligibility.  
Program settings:  
1. Set the jumper on Jx01 to enable the low-pass filter (across pins 2 and 3).  
2. Set the jumper on Jx02 to enable the high-pass filter (across pins 2 and 3).  
3. No jumper on Jx03.  
4. Insert a resistor network in RNx04 that corresponds to the lower limit of the desired frequency passband.  
5. InsertaresistornetworkinRNx02thatcorrespondstotheupperlimitofthedesiredfrequencypassband.Thisfrequencymustbehigher  
than the one selected for the previous step.  
CD Horn Equalization Filter  
A constant-directivity horn requires a 6 dB per octave high-frequency boost from about 3.5 kHz to provide a flat frequency response. On the UF-3  
you must use the CD horn equalization in conjunction with the high-pass filter.  
Program settings:  
1. Set the jumper on Jx01 to bypass the low-pass filter (across pins 1 and 2).  
2. Set the jumper on Jx02 to enable the high-pass filter (across pins 2 and 3).  
3. SetthejumperonJx03toselecttheEQcurveyoudesire:acrosspins1and2for+6dBat20kHz, oracrosspins2and3for+10dBat20 kHz.  
4. Insert a resistor network in RNx04 that corresponds to the desired low-frequency roll-off.  
Subsonic Filter with CD Horn EQ  
CD Horn boost  
Use settings 1, 2, and 4 from the Subsonic Filter, and setting 3 from the CD Horn Equalization Filter.  
This would be suitable only if the loudspeaker system uses passive crossovers.  
Subsonic roll-off  
Figure 7UF-2 as a subsonic filter with CD  
horn EQ  
Subsonic and Ultrasonic Filter  
Use settings 2, 3, and 4 from the Subsonic Filter along with 2 and 3 from the Ultrasonic filter.  
Typ. 16–  
20 kHz  
Typ.  
2050 Hz  
Figure 8UF-2 as a subsonic and ultrasonic  
filter  
5
 
2-Way Active Crossover  
ThisconfigurationroutesthefrequenciesbelowaparticularfrequencytoamplifierChannel1, whichshalldrivethelow-frequencyspeakers, and  
the frequencies above to Channel 2, which shall drive the high-frequency speakers. Using the UF-3 as a crossover requires that you drive both  
amplifier inputs with the same full-band signal.  
HF Driver  
Fc  
Channel 2  
Channel 2  
Amp  
Channel 1  
Channel 1  
SPA-2  
LF Driver  
Figure 9UF-2 as a 2-way active crossover  
Program settings:  
1. Ontheinputmodule, settheamplifiermodetoparallel. Alternately, youcoulduseaY-cabletoprovidethesamesignaltobothchannel  
inputs.  
Steps 2 through 5 configure Channel 1.  
2. Jumper J101 to enable Channel 1s low-pass filter (across pins 2 and 3).  
3. No jumper on J103.  
4. Insert a resistor network into RN102 that is appropriate to the desired crossover frequency.  
5. If you need subsonic filtering, set a jumper on J102 to enable Channel 1s high-pass filter (across pins 2 and 3) and insert a resistor  
network into RN104 that corresponds to the roll-off frequency you desire. If you do not want subsonic filtering, set J102 to bypass the  
high-pass filter (across pins 1 and 2).  
Steps 6 through 9 configure Channel 2.  
6. Set J202 to enable Channel 2s high-pass filter.  
7. Insert a resistor network into RN204 that is appropriate to the crossover frequency you set in #4.  
8. If you need equalization for a constant-directivity horn, set a jumper on J203 for the amount of boost you need. If you do not want CD  
horn equalization, do not place any jumper on J203.  
9. If you need ultrasonic filtering, set a jumper on J201 to enable Channel 2s low-pass filter (across pins 2 and 3) and insert a resistor  
network into RN202 that corresponds to the desired roll-off frequency. If you do not want any ultrasonic filtering, set the jumper on  
J201 to bypass the low-pass filter (across pins 1 and 2).  
6
 
Multi-way Crossover System  
The UF-3 allows you to set up 3- and even 4-way systems. Of course, this also requires that you use more than one amplifier and more than one  
UF-3. The other basic requirement of using the UF-3 as a crossover is that you must feed each amplifier with the same full-range signal and use  
the UF-3 to filter the signals in the individual channels.  
Figure 9 depicts an example of a 4-way system. Because of the multitude of possible system configurations, the fundamentals of the technique  
usedintheexamplewillbeexplainedbelow, withafewspecifics. Theactualcrossoverfrequenciesyoushouldusewilldependonyour  
speaker system.  
UF-3: Mids & Highs  
Ch. 1: LP @ 5 kHz; HP @ 1000 Hz  
Ch. 2 LP @ 20 kHz; HP @ 5 kHz  
Subwoofer  
The subwoofer subsystem in the example is driven by a bridged  
BSC-2  
amplifier. Channel 1 of the UF-3 in this amplifier is set with the high-  
passfilterat20Hz(forsubsonicfiltering)andthelow-passat150Hz,  
which is the crossover point to the woofers. Channel 2 of the UF-3 is  
bypassed.  
BusCard  
Ch. 2  
Ch. 1  
UF-3  
PowerLight 1.6HVX  
Woofer  
The woofers are driven by an amplifier operating in the parallel  
mode. Both channels of its UF-3 are set with the high-pass filter at  
150 Hz (the crossover point from the subwoofers) and the low-pass  
filter at 1 kHz.  
UF-3:Woofers  
Ch. 1: LP @ 1000 Hz; HP @ 150 Hz  
Ch. 2 LP @ 1000 Hz; HP @ 150 Hz  
BSC-6  
BusCard  
Midrange and High Frequencies  
Ch. 2  
Ch. 1  
The remaining speakers are driven by the same amplifier: the mids  
by channel 1, and the highs by channel 2. The settings for channel 1  
of the UF-3 are: high-pass at 1 kHz (the crossover from the woofers)  
and low-pass at 5 kHz (the crossover point to the high-frequency  
drivers).  
UF-3  
PowerLight 3.4  
(parallel mode)  
Channel 2 of the UF-3 is set for high-pass at 5 kHz. For ultrasonic  
protection, the low-pass is set at 20 kHz.  
UF-3: Subwoofer  
Ch. 1: LP @ 150 Hz; HP @ 20 Hz  
Ch. 2 Bypassed  
BSC-6  
BusCard  
Ch. 2  
Ch. 1  
UF-3  
PowerLight 4.0  
(bridged mode)  
Figure 10Multiple amplifiers with UF-3s, set up for 4-way crossover  
operation  
V. INSTALLATION  
Installating the UF-3 requires PC board soldering skills, so only qualified service technicians should attempt it. Any authorized QSC service  
centeror, for an additional installation fee, QSC Technical Services Groupcan perform the installation.  
The UF-3 installs on a BusCard, which mounts inside the amplifier. Make sure you have the right BusCard for the amplifier model.  
The UF-3 also installs on the amplifier input PC board of any QSC EX, MXa, or legacy CX Series amplifier. Some older EX amplifiers may require  
an upgrade to the current input board. Contact the QSC Technical Services Group for details on compatibility with older EX amplifiers.  
When installed, the UF-3 settings and adjustments are not externally adjustable; this can prevent tampering by unauthorized users.  
7
 
Tools and materials you will need:  
Soldering iron  
Desoldering iron or other suitable desoldering equipment  
Phillips screwdriver  
Wire cutters  
Rosin-core solder  
CAUTION:  
Do not use desoldering braid because it may damage the solder pads on the BusCard or input board, and it also might not adequately  
remove solder.  
The UF-3 contains active components which can be damaged by electrostatic discharge (ESD). Be sure to practice standard ESD  
precautions and always ground yourself and your workstation before handling exposed circuit cards.  
Preparing the input board for installation of the UF-3 involves removing solder from feed-through holes on a two-sided circuit card.  
Excessive heat can easily damage the solder pads you will be working on. Proper equipment and experience with desoldering delicate  
PC board circuitry is essential to successfully perform the following procedure.  
Please contact the QSC Technical Services Group if you feel you might not be qualified to perform the installation yourself.  
One last warning: damage caused by an improper installation will void the warranty.  
Installing the UF-3 on a BusCard  
It is easier to configure and install the UF-3 Universal Filter with the BusCard removed from (or not yet installed in) the amplifier.  
Turn off the amplifier and unplug it from the AC. Allow about 10 minutes or longer for the internal voltages to bleed down before you open the  
amplifier chassis.  
If the UF-3 is to be installed on a BSC-6 BusCard (for the PowerLight 3.4, 3.8X, or 4.0), snap off the breakaway section of the UF-3 circuit board  
by flexing it at the pre-scored line.  
Make sure you insert the UF-3 card on the correct side of the BusCard. Insert the UF-3 fully into the holes on the BusCard. Solder all 22 pins to  
the BusCard; make sure you dont create any solder bridges. Then install the BusCard in the amplifier; see the BusCard instructions for details.  
Installing the UF-3 on an input card  
Turn off the amplifier and unplug it from the AC. Allow about 10 minutes or longer for the internal voltages to bleed down before you open the  
amplifier chassis. Disconnect all cables from the amplifiers input panel.  
Position the amplifier so the rear of the chassis is facing you. The input panel is located on the left side of the rear panel. See Figure 11.  
Begin the installation by locating and removing the screws securing both the upper blank and lower input panels to the rear side of the chassis  
(two screws on each mini panel). The upper blank panel will simply drop off when its screws are removed.  
Gently pull the lower input panel out from the amplifier. Once it is removed, you will notice a ribbon cable connecting the input PC board to the  
amplifier. Disengage the locking wing clamps on the ribbon header and carefully remove the ribbon head from the socket on the board. Now the  
input panel assembly is completely free from the amplifier.  
Next, desolder and remove the wire jumper pairs W305/W306 and W405/W406 (W303/W304 and W403/W404 on MXa Series amplifiers).  
Under where the jumpers were are two rows of solder pad holes, one with 10 holes and another with 12. These make up the Mini-Slot,in which  
the UF-3 mounts. See Figure 12.  
LOW IMPEDANCE AUDIO TRANSFORMER  
CH1  
CH1  
70 100 ISOL.OUTPUT  
DIR. OUTPUT  
0
Input card  
70V 25V  
100V  
BRIDGE  
MONO  
CH2  
CH1  
10  
10  
12  
8
0
12  
8
0
LOW IMPEDANCE AUDIO TRANSFORMER  
CH2 INPUT CH1  
GROUND  
CH2  
CH2  
70 100 ISOL.OUTPUT  
14  
18  
24  
6
4
2
14  
18  
24  
6
4
2
DIR. OUTPUT  
0
STEREO  
-dB  
-dB  
LEVEL  
INPUT  
PARALLEL BRIDGE  
LEVEL  
70V 25V  
100V  
BRIDGE  
MONO  
Figure 11Location of the input card  
8
 
Figure 12The legacy CX (left) and EX Series (right) input cards  
Continue preparing the PC board by removing solder from all 22 in-line socket holes. Once this is done, you are ready to install the UF-3.  
With the input panel facing you and the component side of the UF-3 board facing away from you, carefully insert the header pins of the UF-3 fully  
into the socket holes. Turn the assembly over and solder the UF-3 in place. Make sure all the header pins are well soldered. Visually inspect for  
coldsolderjointsandverifythatyouhavesufficientclearancetore-installtheribbonconnectoronthetopsideoftheassembly.Finishbytrimming  
the UF-3 header pins as required.  
Reconnect the ribbon cable to the input board connector. Press the locking clamp wings of the connector closed. You will feel them snap onto  
place.  
If you need to make any adjustments to the UF-3 settings or if you need to record them, do so now, because the UF-3 will be inaccessible once  
the input panel is re-installed into the amplifier chassis.  
Carefully reposition the input board/UF-3 assembly into the amplifier chassis and secure it by fastening the two mounting screws. Make sure  
the screws are tightened snugly, but do not over-torque them. Re-install the upper blank panel.  
Installation of the UF-3 is now complete, and the amplifier is ready to be reinstalled into the system.  
VI. WARRANTY AND DISCLAIMERS  
Disclaimer  
QSC Audio Products, Inc. is not liable for any damage to speakers, amplifiers, or any other equipment that is caused by negligence or improper  
installation and/or use of the UF-3.  
Product Warranty  
QSC Audio Products, Inc. guarantees the UF-3 to be free from defective material and/or workmanship for a period of three years from date of  
sale, and will replace defective parts and repair malfunctioning products under this warranty when the defect occurs under normal installation  
and useprovided the unit is returned to our factory via prepaid transportation with proof of purchase (sales receipt). This warranty provides  
that examination of the returned product must disclose, in our judgment, a manufacturing defect. This warranty does not extend to any product  
which has been subject to misuse, neglect, accident, improper installation, or on which the date code has been removed or defaced.  
9
 
VII. TECHNICAL ASSISTANCE & SERVICE  
Servicing your QSC product requires a trained and qualified technician. There are no user serviceable components inside, and the danger of  
electric shock exists. Additionally, some of the components are QSC-specific parts that require QSC replacements. Comprehensive service  
manuals for most models are available from QSC.  
Technical Assistance  
If you suspect that your UF-3 is defective, check your system configuration and UF-3 settings to determine the origin of the problem. Incorrect  
audio interfacing, poor cabling, or other system-level impairments are the leading causes of problems in audio systems. For technical assistance  
beyond the information given in this manual, contact QSC Technical Services.  
Factory Service  
If your UF-3 needs factory service, contact QSC Technical Services for instructions and a Return Authorization (RA) number. QSC cannot be held  
responsible for products that are returned without a Return Authorization.  
Product Return Guidelines  
1. Pack the product well for protection during shipment. QSC will provide factory packaging upon request, free of charge.  
2. Includeacopyofthesalesreceipt, yourname, returnaddress, phonenumber, anddefectdescriptionwithyourreturncorrespondence.  
3. Call or e-mail QSC Technical Services for a Return Authorization number. Have the products model number and serial number, as well  
as your shipping and telephone information ready at hand.  
4. Mark the Return Authorization number on the outside of the packaging.  
5. Ship the product prepaid to QSC Audio Products. We recommend United Parcel Service (UPS).  
QSC Technical Services  
1665 MacArthur Blvd.  
Costa Mesa, CA 92626 USA  
Telephone:  
+1 (800) 772-2834  
+1 (714) 957-7150  
+1 (714) 754-6175  
Fax:  
+1 (714) 754-6173  
BBS:  
E-mail:  
Web:  
+1 (714) 668-7567  
Qualified Service Centers  
QSC maintains a service center network for your convenience. If you wish to return your product to a local service center, call QSC Technical  
Services for a referral. However, accessories, input modules, and other peripheral QSC products must be returned to the factory for service.  
International Servicing  
ForQSCproductsoutsidetheUnitedStates, contactthedistributorordealerfromwheretheproductwaspurchased. Therearenumerousservice  
centers in many countries. You can get a referral to a service center in your country from your dealeror distributor, or by contacting QSC Technical  
Services.  
10  
 
 
QSC Audio Products, Inc. 1675 MacArthur Blvd., Costa Mesa, California 92626 USA Tel: +1 714 754-6175 Fax: +1 714 754-6174 Web: www.qscaudio.com  
 

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