Shure FP51 Instruction manual

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GENERAL Listed by Underwriters Laboratories Inc.; listed by Cana-
The FP51isa compact, portable, high-qualitygated memory dian Standards Association as Certified
compressor combined with a four-input, one-output
microphone mixer. Designed for applications in broadcasting,
SPEClFlCATlONS
recording and sound reinforcement, the FP51integrates all the
features of professional compressors and mixers in a single
Frequency Response
unit-small and lightweight enough for location use, but with 30 to 20,000 Hz,
2 2 dB
the reliability of a studio console.
Voltage Gain (at 1 kHz)
FEATURES
OUTPUT
40 dB compression range, with compression ratio approx- INPUT PHONES
imately 10:l in normal operating range MIX BUS PHONES (CUE)
Gated memory minimizes "pumping," has LED indicator
True average-responding compression maximizes output Line 55dB 5dB -25dB 65dB 45dB
level regardless of peak-to-average ratio of program Mix Bus 70dB 20dB -- 80dB --
material. Peak-responding circuit reduces gain rapidly for
significant increases in input signal
Inputs
Front-panelresponse rateadjustment (averaging time con-
lMWX)ANCE (at 1 kHz)
INPUT CLIPPING
stant) compensates for variations in program material
INPUT FOR USE WITH ACTUAL LEVEL AT
1 kHz
Extremely low distortion, noise and RF su'sceptibility, with
25-600Qmics
wide, flat frequency response at all compression levels
Reliable operation under wide temperature and humidity
Line level sources
conditions
Mix Bus >3.5k 3.5k +2 dBV
Protected against damage from input overload and
shorted outputs
*Dependent on input control setting.
Four transformer-coupled XLR inputs, each micro- outputs
phonelline switchable with low-cut filter and cuing func-
tions
Phantom power for condenser microphone operation
OUTPUT
Built-intone oscillator permits checking levels and testing
lines
Mic
Transformer-coupled XLR output with microphonelline
switch
Line
Headphonejacks (114-inchand mini-3.5mm)with level con- Mix Bus
trol
Active, feedback-type input gain controls allow high-level Headphones
input signals without input attenuators
Illuminatedtriple-functionVU meter indicatesoutput level, Compressor
dB compression and battery condition Threshold: -88 dBV typical at maximum input gain
Powered by ac (120V or 240V-internally selectable) or (mic); -38 dBV typical at maximum input
built-in battery pack gain (line)
Low battery drain provides up to 10 hours operation under Ratio: 8:l minimum from 10 to 20 dB comprssion
normal conditions 5:l minimum from 10 to 30 dB compression
Noiseless and automatic switchover to and from battery Attack Time: 3 msec for level increases greater than 15
power without affecting compressor dB; 120 msec to
6 sec for increases of less
Rugged, durable construction than 15 dB
Compact and lightweight for field use and transporting Recovery Time: 120 msec to
6 sec
Rack-mountablewith accessory rack mount kit
Copyright 1989, Shure Brothers Inc. Printed in
U.S.A.
27A2216 (IJ)
OUTPUT CLIPPING
LEVEL AT 1 kHz,
5% THD
-34 dBV min.
(150-ohmload)
+ 18 dBm min.
(600-ohmload)
-7 dBV min.
(3.5k load)
+ 7 dBV min.
(200-ohmload)
WJEDANCE (at 1 kHz)
FOR USE WITH
25-600Qmic
circuits
600 ohms
3.5k
8-2000ohms
ACTUAL
1 ohm or
less
185 ohms
3.5k
100 ohms

INPUT LEVEL IMIC I1 IN dBV
COMPRESSIONSYSTEM
INPUT-OUTPUTCHARACTERISTICS
FIGURE 1
Gated Memory
Threshold: -90.5 dBV typical at maximum input
gain (mic); -40.5 dBV typical at max-
imum input gain (line)
Recovery: In "hold" position, less than 20 dB gain
recovery after 1 minute
VU Meter
Dual-range, 3-function(output level in dB, gain reduction in
dB, battery check), illuminated (ac operation only)
Gated MemorylPeak Indicator
With meter switch inVU position, lights6dB below clipping;
with meter switch in Comp position, lights when gated
memory is "holding"
Noise
Equivalent lnput Noise: - 129 dBV (low-impedance
microphone, 150 ohms, 300 to 20,000 Hz) into600-ohm load
at full gain
Equivalent lnput Hum and Noise: -127 dBV (low-
impedance microphone, 150 ohms, 20 to 20,000 Hz) into
600-ohm load at full gain
Output Noise: -77 dBV maximum (output control full
counterclockwise[off]), -40 dBV maximum (output control
full clockwise [on]) (input control down, 300 to 20,000 Hz)
Output Hum and Noise: -75 dBV maximum (output con-
trol down), -38 dBV maximum(outputcontrol up, input con-
trol down, 20 to 20,000 Hz)
Distortion
0.4% THD, 30 to20,000 Hz at + 15dBm output; 0.5% or less
IM distortion at + 15 dBm output into 600 ohms
Common Mode Rejection
65 dB minimum with input of -20 dBV at 100 Hz
Control Interaction
Less than 1 dB with any control combination
Overload and Shorting Protection
Shorting outputs, even for prolonged periods, will cause no
damage; microphone input will not be damaged by signals
up to 3V
Low-Cut Filters
6 dB per octave rolloff at 150 Hz
Phase
All outputs inphasewith respect toall inputs. Pin2 is"high"
with respect to pin 3; pin 1 isground. Tip of mix bus jack in
phase with pin 3. Tip and ring of headphone jacks in phase
with pin 2
Tone Oscillator
1 kHz; + 15 dBm minimum at line output with output level
full up
Phantom Power
30 Vdc nominal, 3.3k series resistance, automatically dis-
abled with input switch in Line position
OperatingVoltage
Ac Operation: 120 or 240 Vac -r-10% (internally
selectable), 50160 Hz, 5.5W
Dc Operation:
27 Vdc nominal at 27 mA typical no-signal,
30 mA typical at 0VU (+4dBm)output; 21.5 Vdc minimum;
battery lifeapproximately 10 hours with alkaline batteries
at
+ 4 dBm output in continuous use; three 9-volt bat-
teries,type NEDA 1604A(Duracell MN1604or Eveready 522
recommended)
Temperature Range
Operating: -18O to 57OC (0° to 135OF)
Storage: -2g0 to 71°C (-20° to 160°F)
Dimensions
79.5 mm H x 310 mmW x 230 mm D(3-118in. x 12-7132in. x
9-1132 in.)
Weight
Net: 2.75 kg
(6 Ib 1 02)
Packaged: 3.25 kg (7 Ib 3 oz)
Certifications
Listed by Underwriters Laboratories Inc.; listed by Cana-
dian Standards Association as Certified
CONTROLS AND CONNECTORS
Power Off-On
Switch: applies power to the FP51 circuitry.
Channel Levellcue Rotary Controls: adjust individual input
channel signal levels. Eachchannel can becued by pulling the
control knob outward to the detent position, rotating the knob
to the desired level, and pushing the knob inward to activate
'the channel.
Lo Cut Filter Slide Switches: reduce unwanted low-frequency
signals such as wind noise by 6 dB per octave at 150 Hz.
Master Rotary Control: determines mixed output level at out-
put connector. The control also sets the tone oscillator level
when the
Tone Osc switch is turned on.
Gated MemorylPeak LED: indicates, in gated memory mode,
that gated memory is "holding" prior amount of compression
during a low input signal, and turns off when input signal is
above compression threshold. In peak mode, the LED indi-
cates approaching program overload. It is activated by the
shortest transient peak, but remains on long enough to pro-
vide easy recognition. The chart below shows the effect of
Compressor and Gated Memory switches on indicator opera-
tion.
GATED MEMORYIPEAK LED FUNCTIONS
Gated Memory off I Gated Memory on
Compressor out No operation
Compressor in Gated memory
VU Meter: indicates 0 VU with a +4 dBm output (recom-
mended for normal use to provide approximately 14 dB
headroom from operating levelto clipping level)with
VUlComp
switch in VU position. Rear-panel VU Range +41+8 slide
switch permits changing to 0 VU
= +8 dBm. With VUlComp
switch in Comp position, indicates compression due to input
signal above threshold (lower meter scale). The VU meter is lit
during ac operation only; therefore, the illumination serves as
a visual alarm if the ac is interrupted and the unit has
automatically switched to battery operation.
Batt Check Momentary Push-buttonSwitch: operates in con-
junction with the VU meter to indicate battery condition. With
the
Power switch on and the switch depressed, a new set of
batteries will give about a
+ 2 VU indication. Battery condition
is good if the reading is above 0 VU; a lower reading means
that new batteries are required for proper operation.
Gated Memory Slide Switch: disables the gated memory
function without affecting other operations.
Response Rate Rotary Control: adjusts the compression
system time constant tocompensate for different types of pro-
gram material. In general, a faster setting (toward the
counterclockwise position) results in a more constant output
level, but a more audible compression effect. Although the
control setting issubjective, thefollowing knob positions offer
guidelines: speech-2; pop music-4; symphonic music- 7.

Compressor Off-On Slide Switch: disables the compressor
and gated memory functions, converting the FP51 to a stan-
dard microphone mixer.
Tone Osc Off-On Slide Switch: provides a highly stable, low-
distortion 1 kHz tone for line tests and level checks. The tone
signal level iscontrolled by the
Master Level control.The tone
signal appears on both the lipe and microphone outputs, as
well as the
Headphones and Mix Bus connectors. The tone
oscillator should be switched off when not in use.
Headphones 1M-inchPhoneJack and Miniature3.5 mm Phone
Jack: permit monitoring mixer output through most stereo
headphones. The
Headphones rotary control adjusts the out-
put level of bothjacks. Notethat the headphones output level
is high enough for use as an auxiliary unbalanced line feed to
drive a tape deck or a power amplifier.
lnput 1-4 XLR Connectors: are transformer-balanced, profes-
sional three-pin audio inputs. Pins 2 and
3 are "hot" and
"neutral," and pin 1 is ground. For microphone operation, the
lnput MiclLine switches must be in the Mic position; for line
level inputs, the switches must be inthe Line position.
Phantom Off-On Slide Switch: controls the application of
phantom power for condenser microphones to all inputs. With
the switchon and
lnput MiclLine switches inthe Mic position,
+30 Vdc is applied to pins 2 and 3 of each input connector
(power is automatically removed in the Line position). Series
current-limitingresistance is3.3 kilohmsfor each input. When
using other than Shure microphones, verify that the voltage
and resistance requirements are compatible.
Output XLR Connector: isa professional three-pinaudio con-
nector for connection to either low-impedance microphone or
line-level inputs of power amplifiers, mixers, or other signal-
processing equipment. The
Output MiclLine switch selects
either microphone-or line-leveloutput signals.
LineOut PushTerminals: provide direct wire connection to a
balanced600-ohmline. Terminals are in parallel with the 3-pin
Output connector when the Output MiclLine switch is in the
Line position only. The red terminal is in parallel with pin 2 of
the
Output connector, andthe black terminal isin parallel with
pin 3. Note that the line-leveloutput signal is always present
on these terminals.
Mix Bus Phono Pin Jack: provides direct access to the out-
put channel mixing bus. This facilitates stacking or "multing"
FP5lsto achieve additional input capacity without losing any
inputs. With two FP5ls connected at their
Mix Bus jacks, for
example, the mix buses of each unit are directly connected,
providing two independent
Master gain controls and two
isolated line amplifiers with eight individually control\ed in-
puts. Since the busesaredirectly connected,a6dBdrop inthe
gain of each output channel will occur, and the
Master or In-
put
controls must be increased to compensate. Noise
specifications are not adversely affected by this connection.
INSTALLATIONAND OPERATION
BatteryOperation
Inaddition to 120-or 240-volt ac operation, the FP51can be
operated from an internal battery pack. Current drain is
typically 30 mA at +4 dBm output level. Battery operation is
recommended for remote, on-location operation, and as an
emergency backup source in case of ac power failure.
Access to the batterycompartment isthrough the bottomof
the chassis. Three 9-volt transistor radio batteries power the
FP51 at full rated out~ut.Duracell MN1604 or Evereadv 522
batteries are recommended. Battery life is approximat~ly10
hours at +4 dBm continuous use. Note that ~hantomDower
loading will increase battery drain.
With batteries in the battery compartment, the FP51 will
automatically and silently switch to battery operation should
the ac voltage fall below a suitable level.
Battery condition can be determined using the
Batt Check
switch on the front panel. With the FP51 Power switch on, ac-
tivate the
Batt Check switch and observe the VU meter. A new
set of batteries will give about a +2 VU indication. Battery
condition isgood if the reading is above 0 VU; a lower reading
means that new batteries are required for proper operation.
Connections
Connect the signal sources to the three-pin XLR lnput con-
nectors. Connect the three-pin XLR
Output connector andlor
Line Out terminals to the input of a power amplifier, mixer,
telephone line, etc. Set the
Output MiclLine switch for the
appropriate signal level.
Refer to the Operating Hints section titled, Additional In-
puts, for information on increasing the number of available
microphone-or line-level inputs.
Connect headphones to the phone jack or 3.5 mm mini
phone jack, if desired, for monitoring the FP51 output.
Connect the linecordtoa 120Vac
2 lo%,50160 Hz source if
the FP51 is to be ac-operated. If 240-volt ac operation is
desired, refer to the Service section.
Adjustments
Turn the Compressor and Gated Memory slide switches on,
the
VUlComp switch toComp, and the VU Range switchto + 4
or
+8 dBm. Rotate the Channel Level and Master Level con-
trols fully counterclockwise to 0, and set the
Response Rate
control for the program material to be used.
If desired, turn on the
Lo Cut Filter switchesabove the Chan-
nel Level
controls. The filter action will help reducewind noise
and undesirable low-frequency signals (see Figure 2).
FREQUENCY IN HERTZ
LO CUT FILTER ACTION
FIGURE 2
Note that each input Channel Level control has a cuing
capability. To cue a channel while the other channels are
carrying programmaterial, pull the desired
Channel Level con-
trol outward to the cue position. This removes that channel
from the mixingcircuitry and routes itonly tothe
Headphones
jacks. Adjust the Headphones level control to a comfortable
listening level, and adjust the cued
ChannelLevel control for a
proper mixing level. Restore the cued signal to the program
mix by pushing the
Channel Level control inward.
Turn on the
Power switchand allow approximately 1minute
warmup time. The VU meter will light inac operation. Turn the
Phantom switch on if non-battery-operated condenser
microphones are to be used with the FP51.
(Caution: Do not
turn the Phantom switch on when using unbalanced low im-
pedance microphones.) Note that phantom power cannot be
applied to the inputs with the
MiclLine switches in the Line
position; if line-levelcondenser microphones (such as Shure's
SM82) are to be operated on phantom power, contact Shure's
Service department for modification instructions.
Turn on the
Tone Osc switch. A dB compression reading of
approximately 10 on the VU meter lower scale will result, and
the
Gated MemorylPeak LED will turn off.
Set the
VUlComp switch toVU and rotatethe Master control
for a 0 VU meter reading (upper scale). The tone signal can be
heard inheadphones connected to either phone jack. The tone
signal can be used to calibrate equipment following the FP51.
Reduce the Master control setting for a -2 VU meter
reading, and turn off the
Tone Osc switch. The Gated
MemorylPeak LED will turn on, indicating that the gated
memory is "holding" the prior amount of compression. Note
the
Master control setting for future use. (Note: This output
reduction is made to compensate for the moderate short-term
output dynamic range encountered for speech using the

suggested response rate setting. A faster setting would
eliminatethe need, but compression would become more audi-
ble.)
Operation
Set the VUlComp switch to Comp, and with an average
sound level entering the Channel 1 microphone, set the Chan-
nel 1
LevellCue control for an average compression readingof
approximately 10 dB. This is the FP5l's recommended
operating level, because with this setting the unit can main-
tain a substantially constant output level for input reductions
of 10 dB and increases of as much as 30 dB.
With the
VUlComp switch inthe Comp position, observe the
Gated MemorylPeak LED. It should remain off during speech
input, and turn on during pauses between sentences and
words (indicating that the compression level is being
"remembered" during program lapses).
Ifthe LEDremainsoff or flickerswith nospoken microphone
input, the acoustic background noise level at the microphone
is near or above the gated memory threshold. This can be cor-
rected by reducing the Channel 1
LevellCue setting until the
Gated MemorylPeak LED stays on without speaking into the
microphone. The compression level is then determined by the
loudness of the talker and the talker's proximity to the
microphones. This adjustment is very important for proper
operation in installations with high background noise levels,
such as sporting events or parades.
Program levels can be monitored by moving the
VUlComp
switchto VU. The meter then indicates programoutput level(0
VU = +4 or +8 dBm). The VU meter is factory-calibratedfor
use with a 600-ohmterminated line. The
VU Range switch on
the rear panel selects either a
+ 4 or a + 8dBm output at 0VU
meter indication. (This switch changes the meter indication
but does not change the actual output level.) Microphone out-
put levels are 50 dB below line output. The +4 range isrecom-
mended for normal use to provide approximately 14 dB of
headroom from operating level to clipping level.
The VU meter is illuminated by a single cartridge-type, 6.3V
incandescent lamp. The lamp is only lit for ac operation. Con-
sequently, the illumination serves as a visual alarm if the ac is
interrupted and the unit has automatically switched to battery
operation.
TheVU meter isconnected on the primary side of the output
transformer to assure protection from any dc level on a
telephone line.
OPERATING HINTS
Large Input Level Changes
If the overall sound and noise levels at the microphone do
not significantly change from those encounteredduring setup
(as indicated by a compression meter reading of 0 to 20 dB),
and if proper operation of the
Gated Memory LED continues,
further control adjustment is not necessary. However, if large
changes in the signal andlor background noise at the
microphone do occur, some
Channel Level control readjust-
ment may beadvisable, based on changes inthe compression
meter readingand actionof the
Gated Memory LED. For exam-
ple, a significant increase inbackground noiseand signal may
occur during an exciting part of a sporting event, so that the
gated memory no longer "holds" during pauses and the com-
pression reads higher than previously. A gradual reduction of
the
Channel Level setting will not be noticeable to the listener,
due to the automatic effect of the compressor, but proper ac-
tion will be restored.
During a later, more subdued part of the program, it may
become apparent that the compression meter is reading near
0, and the
Gated Memory LED does not always turn off during
speech. A gradual increase in
Channel Level setting will allow
operation at the proper level.Thus, during operation, after set-
ting the proper output level with the
Master control, it is
generally only necessary to monitor compression level on the
compression meter and to observe proper action of the
Gated
Memory
LED.
Control setting changes need only be made for long-term,
large signal or noise level changes. It is not necessary to "ride
gain" to maintain a constant line level output as measured on
the VU meter, since that is the compressor's function.
Response Rate Adjustment
Proper setting of the Response Rate control for different
types of program material isdetermined by subjective factors,
that is, by the operator's individual perception of what con-
stitutes"good sound." Generally,
a slower setting will result in
less audible compression, but a wider, short-term output
dynamic range, i.e., a lessconsistent output level.A faster set-
ting means a moreconstant output level, but the compression
effect becomes more audible.
The
Response Rate control setting can be changed during
operation if desired. An initial setting guideline based on pro-
gram material is: Speech-2; Popular Music-4; Symphonic
Music-7. The output leveling effect can be observed for
various settings by observing the VU meter
(VUlComp switch
set toVU), while the subjective effect is monitoredby listening
on headphones.
Multiple Inputs
Up to four microphones or other input sources can be used
with the FP51. With multiple sources, the overall "mixed"
signal and background noise levels determine compression
and gated memory action. For optimum results when several
inputs are used, only the
Channel Level controls for the chan-
nels in use should be turned up.
For a conference or conversation setup, with several "live"
microphones but only one person talking at any time, each
ChannelLevel control should beset sothat eachtalker results
in approximately the same amount of compression. At the
same time, the overall level should be monitored for proper
gated memory action.
Simultaneous Mixed Inputs
With simultaneous mixed inputs (up to four signal sources
operating at the same time), the compressor automatically
maintains a constant overall output level. Therefore, the
balance of signal sources is easily adjusted using head-
phones. Simply observe the compression meter for normal
operating range, and check the
Gated Memory LED for proper
action.
Automatic "Ducking"
The balance between twosound sources can be adjusted to
produce automatic "ducking," that is, the lowering of one
signal as another signal commences. A prime example of this
technique is the lowering of the music level when an an-
nouncer's voice begins. This is accomplished by setting the
Channel Level for themusic source toa low compression level,
say 5dB(withthe
VUlComp switchinthe Comp position).Then
the announcer's
Channel Level isset for a higher level, say 15
dB. When the announcer speaks during musical numbers, the
FP51gain isreduced by 10dB, "ducking" the music level 10dB
below thevoice level.When the announcerstops speaking, the
music returns to full output.
Additional Outputs
If more inputs than the four available on the FP51are need-
ed for the installation, another FP51or any Shure mixer with a
mix bus jack can beconnected. Notethat when the FP51isus-
ed with a different mixer, a compressed output is available
from the FP51 and an uncompressed output is obtained from
the other mixer.
lnputscanalso beadded tothe FP51by connectingthe line-
or microphone-level output of another mixertoone of the FP51
inputs. Theadded mixed input signalswill be processedby the
compressor and gated memory if they are in use.
ExcessiveAmbient Noise
Under certain conditions, such as high noise levels, it may
be impossibleto adjust the
Channel Level control so that the
gated memory can consistently discriminate between
background and program. If this happens, the
Gated Memory
switch should be turned off and the amount of dB compres-
sion reduced to minimize the audible effects of "pumping."
Inextremely severe cases, compression should not be used
at all, because the increase in background noise during
pauses will bequite unpleasant.The FP51canthen be used as
a high-quality linear mixer by turning the
Compressor swritch
off and setting the VUlComp switch to VU to monitor output
level. As with any mixer, set the
Channel Level control as high
as possible without clipping, and set the output VU level with
the
Master control for optimum signal-to-noiseratio.

Fadingwith Compression
lnput fading with a compressor is accomplished somewhat
differently than with a linear mixer. Since a
slow reductionof
input level within the compression region is compensated by
an automatic increase in gain, no audible fading will occur.
Consequently, fading an inputdown should be done rapidly, at
least to the point where the gated memory changes to the
"hold" state.
For overall fades, use the
Master control, since it affects
only the output level, not the amount of compression.
Sound Reinforcement
Some care must be exercised when using the FP51in sound
reinforcement installations. Since the compressor can only
reduce its gain when a signal exceeds its compression
threshold, maximum gain occurs with low-level signals, and
the sound reinforcement system's gain must be adjusted for
stability (no ringing or howling) with no compressor gain
reduction. This can beaccomplished by adjustingsystem gain
with the FP5l's
Compressor switch turned off. With proper
system adjustment, the FP51canbe usedto levelthe sound of
a "wavering" talker, or to prevent power amplifier overdrive
with extremely strong signals.
Single lnput Program Compressor
If the FP51 is to be used as a single-input, permanently in-
stalled program compressor, the signal-to-noise ratio can be
improvedby disablingthe remaining inputs,thusreducing the
electrical noise of the mixing system. This modification is
described in the Service section.
Telephone Interconnection
When using the FP51connected directly to a telephone line,
check tosee whether thetelephonecompany requiresan inter-
face coupler between the FP51 and the telephone line. If a
coupler is required, make certain the coupler selected and the
wiring arrangement are in compliance with local telephone
company regulations. Connect the telephone line to the FP51
Output connector.
When direct connection to a telephone line is not possible,
acoustic coupling to a telephone handset may be used. A
Shure Model 50AC Telephone Acoustic Coupler can be con-
nected to the 600-ohm
Line Out terminals of the FP51and at-
tached to most telephone handsets.
Telephone Line Surge Protection
When usingthe FP51connected directly to a telephone line
subject to lightning-inducedvoltage surges, the following part
(commercially available) can be installed across the
Output
connector to provide additional protection for output circuit
components: Metal Oxide Varistor, General Electric Co.,
Type No. V22ZA1.
ACCESSORY
The ModelA16R Rack Panel Kit consists of a 19in. x3-112in.
(483 mm x 89 mm) precut rack panel and necessary hardware
for rack-mounting the FP51 with its cover in place and end
caps removed ina standard 19 in. (483 mm)audio rack panel.
SERVICE
WARNING
Voltages in this equipment are hazardous to life. Refer
servicing to qualified service personnel.
The FP51 can be disassembled as follows. Remove four
screws securing the cover assembly to the chassis. Carefully
lift the cover assembly up and away from the chassis, taking
care not to snag any wire leads or components. (It is not
necessary to removethe end caps from the cover for accessto
the chassis.)
240 Vac Operation
To change the FP51 operating voltage from 120 Vac to 240
Vac, follow these steps.
1. Locate the Power board.
2. Remove the jumper plug from connector J205 (marked
120V), and carefully insert it in connector J206 (marked
240V), making sure all six pins are properly engaged.
3. Insert the T50mA1250V fuse (packaged with the FP51) in
the fuseholder marked F202.
4. Replace the ac line cord (if necessary) with one designed
for the240-volt source. Ifthe FP51istobeused outsidethe
U.S. and Canada, local regulations may require replacing
the line cord with one having wire insu(ation colors as
follows:
"Live"or Earth or
"Hot" Neutral Ground
US., Canada Black White Green
Europe Brown Blue Green/Yellow
5. Mark the FP51rear panel with the new operating voltage.
Single lnput Compressor
To disable Inputs2, 3 and 4 so that the FP51can operate as
a single-input programcompressor with an improved signal-to-
noise ratio, follow these steps.
1. On the main board, locate interboard connector J302.
2. Lift the connector locking latch upward approximately 3
mm (118 in.) and carefully withdraw the
ribbon cable from the connector.
3. Carefully bend leads 2, 3 and 4 approximately 45O to pre-
vent their reentering the connector. Note that the board is
marked with a "1" for the channel 1 lead.
4. Carefully reinsert the ribbon cable (leads 1 and 5-8)in the
connector housingand depress the locking latch.
5. Mark the FP51 rear panel indicating that inputs 2, 3 and 4
are disabled. This modification will provide an improve-
ment in signal-to-noise of approximately 2.5 dB.
Lamp Replacement
To replace the VU meter lamp (PL501), locate the lamp
directly behind the front panel and above the meter housing.
Using a small screwdriver or fuse puller, carefully remove the
cartridge-type lamp. Replace only with an identical lamp.

REPLACEMENT PARTS LIST
REFERENCEDESIGNATION
BTI-BT3 C202
C203
C204-C205.C323. C325. C335. C379-C382 C206, C702
C301-C304,C316,C342.C350,C368, C370,C375
C317, C322.C327.C332. C366, C703.C705-C706 C329. C601-C602 C369.C707
C372
C374. C377
D201-D204. D206-D207 D205
D301-0312. D314-D325, 0330-D333. D701 D313,0326-D329
D336
D501 F201 F202 J1 J101,J104
J105
J107 J701 J702
L101-L113, L301-L304. L701
MI MPI MP2
SHURE
PART
NUMBER OR
COMMERCIALALTERNATE
Shure 30206FT
Shure 4021OFT
Shure 86A8302;TI TIP30A
ShureMotorola86A350;2N5210 Shure 86A329; Motorola 2N5458
Shure 50601FT
Shure86A335; Rohm ns93
Shure 86A334; RohmTIS92 Shure 50301FT
Shure 50303FT
Shure 50304FT Shure 50305FT Shure 50306FT Shure50311FT -- Shure 50401FT
Shure 50402FT; Alco TPB21RG-PC6 Shure 50403FT;Alco MSS4200
Shure 60402FT;Alco MSS4200RG
Shure 60403FT:Alco MSS4200R Shure 50501FT
Shure 50502FT
Shure 60502FT
Shure 86A808A;RaytheonRC4156DB Shure 50601FT; NationalLM78L12C
Shure 50602FT; TI TL062D Shure 60604FT;Motorola LM393M Shure 50603FT;TI no71
Shure 30601
FT,
NationalLM386N-4
Shure95A8015
DESCRlFllON
Battery,Alkaline, 9V
Capacitor,Electrolytic,330pF, 63V Capacitor,Electrolytic,100pF, 63V
Capacitor,Electrolytic, 10,pF, 35V
Capacitor,Electrolytic,33 pF, 35V
Capacitor,Electrolytic,22 pF, 35V
Capacitor,Electrolytic.4.7 pF, 35V
Capacitor,Electrolytic, 100pF, 35V
Capacitor,Electrolytic.220pF. 16V
Capacitor,Electrolytic.1000,IF, 16V Capacitor, Electrolytic, 470 pF, 35V
Diode.Silicon,1OOV. 112A
Zener Diode.9V, 112W Diode,Computer,75V
Diode, German~um
Zener Diode. 5.6V
Diode, Light-Emiiting.Red
Fuse, Slow-Blow, 3AG, 0.1A. 250V
Fuse, Time Delay, 0.05A, 250V
PhonoPin Jack (MixBus)
Connector,%SocketXLR (Input)
Connector,3-Pin XLR (Output)
DualPushTerminal (LineOut)
PhoneJack, 3-Circuit Switching
(Headphones) MiniPhoneJack, 3-Circuit
Switching (Headphones) FerriteBead Ring
Meter, VU/Comp
Knob(ChannelLevellcue) Knob(MasterLevel)
REFERENCEDESIGNATION
MP3 PL501
Q201
Q202-Q203,Q306.0308, Q310 0301-Q305, Q311-0312 Q307.Q309 P313.Q315 Q314
R317-R320
R340.R.383,R420 R343 R363.R411.R430 R364 R701 5301-5304 S501-S508
S509 S510
S601-S604, S606 S605, S607 T201 T301-T304 T305 U301,U304-U306
U302 U303,U309
U307-U308 U310
U701
W25
SHURE
PART
NUMBER OR
COMMERCIALALTERNATE
Duracell MN1604 Shure 60111FT;
Sprague503D337F063CK;
Shure40101FT; Sprague503D107F050PD Shure 60112FT: Sprague503D107F050W Shure 40102FT; Nichicon1V330MAA
Shure 40103FT;
Sprague503D226M050LA Shure60105FT; PanasonicECE-A35ZR7 Shure 60107FT; NichiconIVlOlMPA Shure30107FT Shure 101l2FT; NichiconlClO2MRA Shure 60108FT; Sprague503D477F035QE Shure 86A404; Motorola1N4002 Shure60202FT; Motorola IN5239 Shure 86A415.TIIGE 1N4148 Shure 66A405; RCA SK3087 (IN48) Shure50201FT;
Motorola 1N56232A
Shure 60206FT; Rohm SLR340R3 Shure 80F159;Littelfuse 313.100
Shure 60208FT;Littelfuse218.050
Shure 50202FT
Shure60216FT:CannonXLB-3-31WV Shure 60217FT; CannonXLB-3-32WV Shure 10202FT Shure 60218FT Shure 20203FT Shure 60219FT;Stackpoie57-3425 Shure50203FT
Shure 50204FT
Shure 50205FT
DESCRlFllON
Knob(ResponseRate
8
Headphones)
Lamp. Meter.6.3V. 150mA
Transistor, NPN
Transistor, NPN
Field Effect Transistor
FieldEffectTransistor
Transistor.PNP
Transistor, NPN
Potentiometer,Dual
50k150k (ChannelLevellCue) Potentiometer, Trimmer,50k Potentiometer.CW AudioTaper. 200k (Master) Potentiometer, Trimmer. 5k Potentiometer, LinearTaper, 2M
(ResponseRate)
Potentiometer,CW Autio Taper, 10k
(Headphones)
PartolR317-R320
Switch. Slide DWT (LoCut. Tone OSC.Compressor,GatedMemory. VUIComp)
Switch.Push-button (BattCheck) Switch, Slide. 4PDT (Power)
Switch. Slide, 4PDT (MiclLine)
Switch,Slide, 4WT
(Phantom,VU Range)
Transformer, Power
Transformer,
Input
Transformer,Output IntegratedCircuit,OpAmp IntegratedCircuit. Op Amp
IntegratedCircuit.OpAmp IntegratedCircuit,DualComparator
IntegratedCircuit. OpAmp
integrated
Circult. Audio Amp
Line Cord and Plug, 3-Conductor
Grounded, 1.Em (6
ft)

PRINTED CIRCUIT BOARDS
Component Side
PRINTED CIRCUIT BOARDS
Solder Side