Shure Audiomaster 1200 User Manual

Model 1200 Powermixer

Price $7.50

SERVICE MANUAL

ISSUE NO. 1

Manufactured by

SHURE BROTHERS INC.

222 Hartrey Avenue

Evanston, Illinois 60202-3696

Copyright 1988, Shure Brothers Inc.
AL954 (HE) 27A8187

Printed in U.S.A.

SPECIFICATIONS

Type

Mono Powermixer

Frequency Response

Flat +1, -3 dB, 40 Hz to 20 kHz (any input to any output)

Inputs

Six input channels: six unbalanced high- and/or bal­anced low-impedance inputs; channels 1 and 2 high­impedance inputs switchable to Aux level; available
expansion modules* each contain 2 high- and 2 low­impedance microphone inputs; two modules (4 chan­nels) can be added to each 1200

Power Output (1 kHz, 120 Vac, 1% THD)

200 watts minimum with 4 ohm speaker
120 watts minimum with 8 ohm speaker

Distortion

THD typically less than 0.15% at 1 kHz, 0.35% at 70 Hz

and 20 kHz (180 watts to 4 ohms, measured from low-

impedance input, Input Attenuation, individual channel

and Master Volume controls at typical user settings)

IM distortion typically less than 0.4% (116 watts to 4
ohms, Input Attenuation, individual channel and Master
Volume controls at typical user settings)

Low- and High-Frequency Equalization (Individual channel

and Monitor)

±10 dB at 100 Hz and 10 kHz

Input OVERLOAD Indicators

Illuminate 3 dB before clipping of input preamplifier or
equalizer stage

Power Amp Limiter

Threshold: 1.5 dB below speaker output clipping level

Input signal range: 15 dB beyond limiting threshold

Output PEAK/LIMIT Indicator

With Limiter Out: Lights 2 dB before clipping at speaker

outputs
With Limiter In: Lights 0.5 dB before onset of Limiter

action

Output NORMAL Indicator

Lights when speaker output level is greater than 1.4
Vrms (0.5 W into 4 ohms)

Input Sensitivity (full power output)

BAL LO Z: -66 dBV (0.5 mV)

HI Z: -44 dBV (6.3 mV)
AUX: -26 dBV (50 mV)

PA INPUT: 0 dBV (1.0 V)

Input Clipping Level

INPUT

CLIPPING LEVEL

ATTENUATION

BAL LO Z -33 to -3 dBV 0 to -30

(22 to 707 mV)

HI Z

-11 to +18 dBV 0 to -30

(281 mV to 8.41 V)

AUX +6 to +36 dBV 0 to -30

PA INPUT -1 dBV

2 to 63 V

--

(891 mV)

Voltage Gain (at 1 kHz)

INPUT OUTPUT

SPEAKERPGM MIXMONITORPHONES

LO Z

HI Z 73 dB

95 dB 65 dB

43 dB 49 dB

AUX 55 dB 25 dB

PA

29 dB - - 16 dB -

71 dB

31 dB

82 dB51 dB
60 dB29 dB

42 dB11 dB

TAPE

Output Clipping Level

OUTPUT
SPEAKER

MONITOR
PROGRAM MIX
PHONES

TAPE

MINIMUM CLIPPING LEVEL

+29 dBV (28 V)
+18 dBV (7.9 V)
+18 dBV (7.9 V)
+16 dBV (6.3 V)
+18 dBV (7.9 V)

Impedance

INPUTS
LO Z MIC

HI Z MIC

AUX

PA

ACTUAL

1 kΩ

130 kΩ

50 kΩ
50 kΩ

FOR USE WITH
75 to 600 Ω

100 kΩ or less
10 kΩ or less
10 kΩ or less

OUTPUTS

MONITOR
PROGRAM MIX

TAPE

PHONES
SPEAKER

2.4 kΩ 2 kΩ or more

2.4 kΩ 2 kΩ or more

2.4 kΩ
430 Ω 4 Ω or more

-

2 kΩ or more
4 Ω or more

Hum and Noise

Less than -126 dBV equivalent input hum and noise

(20 Hz to 20 kHz, LO Z input to SPEAKER output)

Noise

Less than -127 dBV equivalent input noise (300 Hz to

20 kHz, LO Z input to SPEAKER output)

Signal-to-Noise Ratio

Greater than 80 dB (below full output) at typical control

settings

Phantom Power

24 Vdc ± 10% open circuit, 1.8 k series resistance

Power Requirements

120 Vac ± 10%, 50/60 Hz, 420 watts typical with no ac

receptacle load

AC Convenience Receptacle

120 Vac, 100 watts maximum

Certifications

Listed by Underwriters Laboratories Inc. and by

Canadian Standards Association as certified

Environmental Conditions

Operating Temperature: -7 to 43°C (20 to 110°F)
Storage Temperature: -40 to 74°C (-40 to 165°F)

Relative Humidity (Operating and Storage): 0 to 95%

Overall Dimensions

191 mm H x 483 mm W x 343 mm D (7-½ x 19 x 13-½ in.)

Weight

12.3 kg (27 lb)

18.2 kg (40 lb) in A1200C Carrying Case

RECOMMENDED LOUDSPEAKERS

AUDIOMASTER Model 3200, 100 W, 8 Ω, vented two-way
speakers

OPTIONAL ACCESSORIES

Carrying Case. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1200C

Input Expansion Module*

(2 channels, 2 each HI Z and LO Z inputs). . A1200MX

Speaker Cable, 15 m (50 ft) with phone plugs

Line Matching Transformer (LO Z to HI Z)

. . . . . .

. . . . . . . . .

A50SC
A95UF

240-V Conversion Kit* . . . . . . . . . . . . . . . . . . . . . . . . RKC209

Phono Preamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M64A

*For installation by qualified service personnel only.

MODEL 1200 SERVICE MANUAL

TABLE OF CONTENTS

Description
For Years of Dependable Service

Troubleshooting ..................................

Service Instructions

External Parts

Diagnosis .....................................

External Fuse Replacement
Service Access
General Service Procedure
AC Voltage Measurements
DC Voltage Measurements
Resistance Measurements
Chassis-Mounted Boards and Components

A1 Reverb Pan
SHR-11 (and SHR12) Power Amplifier

SHR-12 Temperature Sensor Board
SHR-14 Main Board

Rear-Panel Boards and Components

SHR-10 Input-Output Board
SHR-03 Aux/Mic Board
SHR-02 Hi-Z Input Board

SHR-01 Lo-Z Input Board.......................

SHR-13 Speaker Output Board
B1 Fan
S3 Phantom Power Switch

Front-Panel Boards and Components

SHR-04 Channel Board (6)......................

Front Mounting Panel
SHR-05 Master Control Board
SHR-09 Limiter Board
SHR-06 Headphones Output Board and

SHR-08 Indicators Board

S2 On/Off Switch
A1200MX Input Expansion Module
Checking Active Components
Ferrite Beads
Service Illustrations
Optional Accessories

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Board Assembly

SHR-11 Potentiometer Adjust

VR1101 Output Voltage Offset
VR1102 Driver Balance

VR1103 Idle Current
VR1201 Temperature Sensor Threshold
VR1401 Power Amplifier Limiter Threshold

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SHR-07 Headphones Control Board

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DESCRIPTION

The Shure Model 1200 AUDIOMASTER® Powermixer is a

compact, flexible microphone mixer with six inputs for high- or

low-impedance sources and a 200-watt power amplifier. The

1200 is human-engineered for ease of setup and operation.

Connection of microphones, speakers and other equipment

(tape recorder, equalizer, effects device, remote amp, etc.) is

fast and convenient.

The 1200 is rack-mountable or portable. Its 6 inputs are

expandable to 8 or 10 inputs through the use of A1200MX

Expansion Kits. Inputs accept both high- and low-impedance
microphones (dynamic, ribbon or condenser), as well as ampli-

fied instruments or other high-level sources. Individual channel

input attenuators with overload indicators permit precise gain

control to prevent input overload. The 1200 has built-in rever-

beration with individual channel and overall level adjustments.

Other effects devices or an equalizer can be connected through
a post-master control program loop. An integral power amp
limiter prevents overload distortion over a wide signal input
range. Pre-volume monitor send controls and pre-master vol­ume tape output provide maximum versatility in stage or record­ing applications. The control panel has color-coded knobs for
ease of adjustments, while LED indicators give instant notice of
operating status.

In addition to the A1200MX Expansion Module, the following
accessories are available for the 1200: A1200C Carrying Case,
A95UF Line Matching Transformer, RKC209 240 V Conversion
Kit, and M64A Phono Preamplifier.

The 1200 is Listed by Underwriters Laboratories, Inc., and

listed by Canadian Standards Association as certified.

1

FOR YEARS OF DEPENDABLE OPERATION...

The AUDIOMASTER® System is exceptionally well designed,
with all components of the highest quality, operating well within
their respective ratings to assure long life. The following list of
Do’s and Don’ts describes minimal operating precautions and
maintenance to provide years of dependable service.

DO

use a 16 AWG or larger, heavy-duty, 3-conductor extension

cord when additional line cord length is needed.
DON’T replace the rear-panel fuse with a different size or type.

Use only 5 A, 250 V, Type 3AG.
DON’T operate the Powermixer with its air vents blocked; don’t

place it on a radiator or heat-producing equipment. Avoid oper­ation in direct, hot sunlight.

DO unplug the Powermixer before cleaning. Use only mild
detergent and a damp (never wet) cloth to clean the outer

SYMPTOM

Powermixer is “dead” (no output, POWER LED off)

OVERLOAD LED illuminates, either

A.

Flickering with program material, indicating abnormal
speaker load

B.

Continuously to indicate power amplifier shutdown

No signal at speaker (all other functions appear normal), either

A. NORMAL LED illuminated, or
B. NORMAL LED not illuminated

Fuse blown

One of two inputs on same channel not working properly (both

1/4-inch and 3-pin jacks in use)

surfaces; Don’t use strong solvents or cleaning fluids.
DON't use unbalanced low-impedance microphones with the

PHANTOM 24V switch on; turn off the switch if not required for
powering condenser microphones. If phantom power is in use,
connect unbalanced low-impedance microphones through a
line matching transformer (Shure A95UF) to a HI Z input. Phan­tom power will not affect balanced low-impedance dynamic
microphones.

DON’T risk fire or shock hazard by operating the Model 1200
in the rain.

TROUBLESHOOTlNG

Should any difficulty be encountered in operation of your AUDIO­MASTER System, the trouble can often be traced to some
simple source. The following is offered as a basic guide to
solving this kind of problem.

PROBABLE CAUSE AND CORRECTION

1.

Check that ac power source is “live” and Model 1200 is
plugged in.

2. Check that POWER switch is on.

3.

Check that rear panel fuse (5 A, 250 V) is good.

4.

If the 1200 has turned off due to excessive internal tempera­tures, allow at least an hour for cooling, and reactivate unit.
If difficulty persists, refer to General Service Procedure in
this manual.

1.

Check total speaker load (must be no lower than 4 ohms)
and for possible shorted speaker cable.

1.

Check air vents for blockage.

2.

Check that internal fan is operating (fan located on rear

panel).

3.

Turn MASTER volume control down for several minutes to
allow proper cooling. If difficulty persists, refer to General
Service Procedure.

1.

Check for defective or improperly connected speaker cables.

1. Check settings of channel VOLUME and MASTER VOLUME
controls.

2. Check connections to EXTERNAL DEVICE LOOP

1. Replace with identical fuse (5 A, 250 V, 3AG).

2.

If second fuse blows, refer to General Service Procedure.

1.

Make sure similar microphones are used on both inputs,
and microphone impedances match the inputs used.

2.

Make sure a low-impedance microphone is not used with
aux level equipment on other input.

3.

Make sure MIC/AUX switch is in MIC position (Ch. 1 and 2

only).

4.

Make sure microphone switches are on; check microphone

cables.

2

SYMPTOM

INPUT OVERLOAD LED flashing

NOTE: Occasional flashing is acceptable

Loud clicks when certain microphones or cables are used

No MONITOR output (program output normal)

Sound quality poor (weak or thin)

SERVICE INSTRUCTIONS

PROBABLE CAUSE AND CORRECTION

1.

Adjust INPUT ATTENUATION counterclockwise to reduce
channel input level.

2.

Reduce input signal level at source.

1. Make sure PHANTOM 24V switch is not on (when not needed).

2. Make sure unbalanced low-impedance microphone or cable

is not used when PHANTOM switch is on.

3.

Check for defective microphone cables.

1.

Make sure channel MONITOR and MONITOR MASTER

controls are turned up.

2.

Make sure controls on external equipment connected to
Monitor output jack are turned up.

3.

Check for defective cable from MONITOR output jack.

1.

Check for excessive treble boost or bass cut on equalization
controls.

2.

Check PROGRAM and MONITOR output jacks for signal

quality (if acceptable, problem is in power amplifier section).

3.

Check for defective cables.

4.

Check impedance match (high- or low-impedance mics)

at input.

EXTERNAL PARTS

The knobs and feet can be replaced without disassembling

the 1200. All knobs are of the pull-off type, and are color-coded

by function. The Equalization knobs are dual concentric types;
all other knobs are single.

DIAGNOSIS

A simple method of localizing problems without opening the
1200 is as follows. Turn off the Power switch. Do not connect a
speaker or headphone load. Set all controls of the channel
under test only to full clockwise (other channel volume and
monitor controls full counterclockwise), except: Reverb Return
full counterclockwise, and Eq controls centered. Turn the unit
on and apply a 0.5 mV, 1 kHz test signal across pins 2 and 3 of
one of the Bal Lo Z input connectors. Normal voltmeter readings

taken at each output connector are given in Table 1. Similarly, a

5 mV signal inserted in a HI Z input, 50 mV in an AUX input, or
891 mV in the Power Amp and Monitor Inputs will yield similar
output voltages. This method is useful for saving time in localiz­ing problem areas. Internal servicing should be performed only
by qualified service personnel.

TABLE 1. NOMINAL TEST VOLTAGES

OUTPUTS

INPUT

LO z 0.5 mV 28 V
HI Z
AUX
PA

Input

50 mV

891 mV 25 V

Spkr Prgm Mix

890 mV

5 mV 22 V 708 mV

28 V 890 mV 1.78 V 6.31 V

Mon Phones

1.78 V

1.41 V

--- ---

Tape

6.31 V

5.01 V 141 mV

5.62 V

178 mV

178 mV

---

WARNING

Voltages in this equipment are hazardous to life. Refer

servicing to qualified service personnel.

EXTERNAL FUSE REPLACEMENT

To replace line fuse F1 (with no apparent problems in the
Powermixer), disconnect the line cord from the ac source and
remove the rear panel fuseholder cap by pushing it in and

turning it counterclockwise (either a screwdriver or fingertip

may be used.) Replace the defective fuse only with a 5A 250V
Normal Blow type.

CAUTION

If trouble symptoms (overheating, erratic operation, etc.)
were apparent before the fuse blew, or if the replacement
fuse blows, a qualified service person should trouble-

shoot the Powermixer carefully to find the source of the

problem. Do not continue to replace fuses; have the
trouble corrected.

SERVICE ACCESS

Disconnect the 1200 from its power source. To open the unit
for servicing, remove ten screws and lockwashers from the top
and five from each side of the cover. The cover can then be

lifted off exposing the internal parts (see Figure 1).

3

PRINTED CIRCUIT BOARD AND PARTS LOCATION

FIGURE 1

After replacing high-voltage parts such as the fan, power

WARNING

cord, rear panel convenience receptacle, or printed wir­ing assemblies SHR-11, SHR-12, or SHR-14 (or their
components), make certain that a dielectric voltage
breakdown test is performed before connecting the unit
to a power supply. With the unit disconnected from the ac
source, turn the unit on and measure the resistance
between the ground contact of the power plug and each
of the other two prongs. This resistance should measure
infinite. Then measure the resistance between the plug
ground and exposed metal parts of the chassis, screws,
connectors, fan grille, etc. This resistance should be zero
ohms. If any measurements are recorded outside the
specified limits, a shock hazard exists. The unit must be
repaired and rechecked before it is returned to operation.

IMPORTANT: When removing any printed wiring board, be sure
the wires and connectors detached from the board are identified
for proper reconnection. This may be done by affixing a piece
of masking tape marked with the reference designation
(connectors) or terminal letter or color (wires).
NOTE: Any cable ties that were loosened or removed must be
tightened or replaced after servicing.

Similar wire colors and connectors with the same number

CAUTION

of pins are used in different circuits; make sure proper

reconnections are made. Push-on connectors must be

removed by pulling straight out. The side of a small screw­driver blade inserted between the free and fixed connector
can sometimes be helpful in separating the connector.

Do not apply side force when removing or reconnecting
terminals, or damage may result. Reference to the service

illustrations will be helpful in case of difficulty.

GENERAL SERVICE PROCEDURE

To isolate a problem area, a general procedure is as follows. If
the Powermixer is completely dead, check the ac power source,
line cord, and fuses (external and internal). If the unit turns on
but operation is abnormal, check the chassis power supply
output (-56 Vdc between test point SHR-11-AB and ground,
and +56 Vdc between test point SHR-11-AA and ground; -15

Vdc across C1421, +15 Vdc across C1420, and +24 Vdc

between P1404-A and ground). If the measured dc voltages are
correct, perform additional AC and DC Voltage Measurements
as described below to isolate the problem.

4

AC VOLTAGE MEASUREMENTS

Numbers within rectangular symbols on the circuit diagrams
denote ac voltages at that point under the following test
conditions:

1.

Voltages measured with respect to chassis unless other­wise indicated.

2. Line voltage: 120 V, 60 Hz.

3.

Test signal of 0.5 mV across pins 2 and 3 of connector
J101.

4. AC voltage measurements may vary ±20% from values
shown.

5.

Measurements made with ac voltmeter of 1 megohm or
greater input impedance.

6.

No load on Speaker Outputs.

7.

All controls (of channel under test only) full clockwise

except Equalization controls centered.

8. Reverb Return full counterclockwise.

9. Limiter switch and Phantom switch in Off position.

10.

Monitor Master control clockwise.

DC VOLTAGE MEASUREMENTS

Numbers within elliptical symbols on the circuit diagrams
denote dc voltages at that point under the following test
conditions:

1.

Voltages measured with respect to chassis unless other-

wise indicated.

2. Line voltage: 120 V, 60 Hz.

3.

No input signal applied.

4.

Dc voltage measurements may vary ±20% from values
shown.

5.

Measurements made with dc voltmeter of 11 megohms or
greater input impedance.

6.

Phantom switch in On position.

RESISTANCE MEASUREMENTS

With the ac line cord disconnected from the ac source and
the Power On/Off switch off, the following ohmmeter measure-

ments may be made.

1.

Reverb pan output coil: approximately 360 ohms; input

coils approximately 40 ohms.

2.

Transformers may be checked for continuity of each winding.

3. To test transistors, ICs and diodes, refer to the section on
CHECKING ACTIVE COMPONENTS.

To replace the reverb pan, connect the white lead connector
to the reverb Input and the orange lead connector to the reverb
Output. Use the previously removed screws to secure the reverb
pan to the reverb shield, and to secure the shield to the chassis
bottom and the parallel vertical interior shield. Be sure to replace
any cable ties that were removed or loosened.

SHR-11 AND SHR-12 POWER AMP BOARD ASSEMBLY

The Power Amplifier Board Assembly consists of SHR-11
and SHR-12 mounted on the large aluminum heat sink. To
separate the heat sink and its associated boards from the 1200,
remove the screws holding the sink to the power transformer
shield bracket, and those holding the sink to the metal shield

that divides the fan from the input and output connectors and

boards. Disconnect the connectors from P1101, P1102 and
P1201, and unsolder the red, green, and white leads from AA,

AB and AC, respectively, on SHR-11. (The opposite ends of

leads AA and AB are connected to SHR-14, Main Board; the
opposite end of lead AC is connected to SHR-13, Speaker
Output Board.) The Power Amp Board is now free of the 1200.

To replace parts on SHR-11, it is then necessary to remove
SHR-11 from the large heat sink. Do this by removing the four
Phillips screws holding the power transistors at the corners of

the board, and the two Phillips screws holding the board on the

brass standoffs.

NOTES:

1.

Removal of SHR-11 from the heat sink may damage the
insulators below the power transistors. Therefore, when
servicing SHR-11, be prepared to replace all four 802639FK
insulators. If either predriver transistor Q1103 or Q1104
(mounted on the vertical heat sink fastened to SHR-11)
is replaced, be prepared to replace insulator 802681FK
beneath it.

2.

If transistor Q1105, mounted on the solder side of board
SHR-11, is replaced or if the board has been removed from
the heat sink, make certain that Q1105 physically contacts
the large heat sink after reassembly of the board to the heat
sink is completed. Apply a small amount of Wakefield Type

120 Thermal Joint Compound to the top surface of the
transistor in order to ensure proper heat transfer.

CHASSIS-MOUNTED BOARDS AND COMPONENTS

The following printed wiring boards and components are

chassis-mounted.

SHR-11
SHR-12

SHR-14
A1
T1

POWER BOARD
SENSOR BOARD
MAIN BOARD
REVERB PAN
POWER TRANSFORMER

REVERB PAN

To remove the reverb pan assembly, turn the 1200 on its side

(power transformer down) and remove the three screws holding
the reverb shield to the chassis bottom. Turn the 1200 upright
and remove the screw holding the reverb shield to the standoff
attached to the parallel vertical interior shield. Disconnect the

phono connectors at the bottom of the reverb pan assembly.

Remove the four screws holding the reverb pan to the vertical

metal interior shield, and lift the reverb shield and pan assembly
out of the chassis holding the pan to the shield. (If necessary to
free the reverb shield, remove the cable tie(s) holding the
orange and white leads to the metal shield.)

To replace SHR-11 in the 1200, solder the red, green and
white leads to AA, AB and AC. Connect the cable assembly with
three leads from P1405, SHR-14, to P1101 ; and connect the
cable with a single lead from P1407, SHR-14, to P1102.

SHR-11 POTENTIOMETER ADJUSTMENT

If any components are replaced on SHR-11, trimpots VR1101,
VR1102 and VR1103 may require readjustment. Measure the
SHR-11 voltages described in the following paragraphs. If

measured voltages are not correct, make adjustments as follows.

With power off, no input signal applied, and no load on the

1200’s speaker output, turn VR1103 completely clockwise. Turn
power on and allow unit to warm up or thermally stabilize for ten
minutes prior to making the adjustments. See Figure 2 for
trimpot locations.

5

VR1101 OUTPUT VOLTAGE OFFSET ADJUSTMENT

1.

Connect a dc voltmeter between SHR-11 terminal AC and
ground (see Figure 2).

2.

Adjust VR1101 so that V1 equals 0 V ±15 mV

VR1102 DRIVER BALANCE ADJUSTMENT

1.

Connect a dc voltmeter between CP1101 and ground (see
Figure 2).

2. Adjust VR1102 so that V2 equals 1.2 V.
VR1103 IDLE CURRENT ADJUSTMENT

1.

After the unit has been turned on for at least five minutes,

connect a dc voltmeter between R1126 and R1127 as shown
(see Figure 2) and check the idle current. If the value of V3

does not equal 6.6 mV ±3.3 mV, use a razor blade to carefully

remove from the top and side of VR1103 the old cement that
prevented its adjustment from changing.

2. Adjust VR1103 so that V3 equals 6.6 mV ±3.3 mV.

3. Apply a drop of cement (white glue, hot melt glue, caulk, etc.)
to VR1103 to eliminate movement due to vibration.

VR1201 TEMPERATURE SENSOR THRESHOLD ADJUSTMENT

If U1201 or other SHR-12 parts are replaced, VR1201 will

probably require recalibration as follows.

1.

Turn off the unit long enough for the heat sink to reach
ambient temperature. Remove all input signal sources and

speaker loads.

2.

Measure the heat sink temperature or ambient temperature
around the heat sink. Consult the graph in Figure 3 to
determine the proper voltage at test point CP1402.

3.

Attach a dc voltmeter between CP1402 (+) and ground (-).

4.

Apply power to the unit and quickly adjust potentiometer
VR1201 on SHR-12 until the proper voltage is reached.

SHR-11 POTENTIOMETER ADJUSTMENTS

FIGURE 2

SHR-12 TEMPERATURE SENSOR BOARD

To remove SHR-12 from the large heat sink, remove the
Power Amplifier Board Assembly from the 1200 as described
above. Then remove the two Phillips screws that hold SHR-12 to
the small vertical heat sink. When replacing SHR-12, U1201
(mounted on the solder side of the board) must physically
contact the vertical heat sink in order to ensure correct opera­tion of the power amplifier over-temperature protection circuitry.
In addition, apply a small amount of Wakefield Type 120 Thermal
Joint Compound to the top surface of the IC to allow good heat
transfer.

TEMPERATURE SHUTDOWN SENSOR CALIBRATION

FIGURE 3

SHR-14 MAIN BOARD

The 1200 contains four internal fuses mounted on the Main
Board (SHR-14). If replacement becomes necessary, replace
only with identical Normal Blow fuses: two 0.75 A 250 V, and two
8 A 250 V. Do not continue to replace fuses if a fuse continues to
blow; have the trouble corrected.

To remove SHR-14 from the chassis, remove the three Phillips
screws on each of the long sides of the board and the single
screw next to the two 8 A fuses on the short side of the board.

This will allow the board to be lifted free of the chassis. If it is

necessary to completely separate SHR-14 from the 1200,
remove all seven connectors (be sure to label the four 4-pin
connectors and their receptacles to ensure proper reattachment).
Unsolder the six transformer and two fan leads from pins AA
through AH, and the two ground leads connected to Al and AJ.
Be sure to label leads also so they can be resoldered to the
proper pins. Unsolder from connection pins AA and AB of
SHR-11 the red and green wires attached to the solder side of
SHR-14. (Remove cable ties as necessary.) The SHR-14 board
can now be completely detached from the 1200.

6

If any of the heat-sink-mounted parts (voltage regulators
U1408, U1409 and U1410, or silicon rectifiers D1423 and D1424)
is replaced, be sure to apply a small amount of Wakefield Type
120 Thermal Joint Compound between the component and the
heat sink to allow maximum heat transfer.

A number of components on SHR-14 are mounted on spacing
insulators to keep them a measured distance from the board,
e.g., R1460, D1422. If any of these parts is replaced, be sure to
remount them the required distance above the board on spacing
insulators as originally supplied.

VR1401 POWER AMPLIFIER LIMITER THRESHOLD ADJUSTMENT

This adjustment is made under the following conditions.

1.

Terminate the Speaker Output in a 4-ohm resistive load.

2.

Set the Master control and trimpot VR1401 on SHR-14 fully
clockwise.

3.

Set the Limiter switch to Out.

4.

Connect the unit to a 120 Vac, 60 Hz power source and
switch the unit on.

5.

Drive one low-impedance input channel at 1 kHz with its
channel control fully clockwise. (Turn all the other input
channel Volume Controls fully counterclockwise.) Increase

the input signal until the signal at the Speaker Output just

visibly clips.

6.

Reduce the input signal level such that the output voltage
drops 1.5 dB.

7.

Switch the Limiter In. Slowly turn trimpot VR1401 counter­clockwise until the output voltage drops an additional 0.2 dB.

REAR-PANEL BOARDS AND COMPONENTS

The following printed circuit boards and components are
mounted on the rear panel.

SHR-10

INPUT-OUTPUT BOARD
SHR-03 AUX/MIC BOARD
SHR-02
SHR-01
SHR-13
B1
S3
W1
J1
XF1

HI-Z INPUT BOARD

LO-Z INPUT BOARD

SPEAKER OUTPUT BOARD

FAN

+24 VDC PHANTOM POWER SWITCH

POWER CORD

AC CONVENIENCE RECEPTACLE

EXTERNAL FUSEHOLDER

SHR-02 HI-Z INPUT BOARD

To remove SHR-02, remove the six 1/2-inch nuts on the input
jacks. Disconnect the four 3-pin connectors from the SHR-01
LO-Z INPUT BOARD and the two 3-pin connectors from the
SHR-03 AUX/MIC BOARD. Pull the board straight back to
disengage the jacks from the rear panel: SHR-02 can then be
completely separated from the 1200.

SHR-01 LO-Z INPUT BOARD

Remove the twelve screws (two per input) connecting the
XLR-type connectors to the rear panel. To remove SHR-01 without
first removing SHR-02 HI-Z INPUT BOARD, remove the four
Phillips screws that hold the rear panel to the chassis bottom.

Rest the unit on its side while performing this operation. Then

swivel the rear panel away from the chassis (it is still held by the

power cord). This allows SHR-01 to be pulled straight back and
away from the rear panel without being stopped by the interior
vertical metal shield. Disconnect the four 3-pin connectors (two
from SHR-03 and two from SHR-04 CHANNEL BOARDS) and
the four 4-pin connectors (from SHR-02 and SHR-04). (Be sure
to label all removed lead-connector assemblies.) Unsolder from

point AA the yellow lead from SHR-10 REAR PANEL INPUT­OUTPUT BOARD: SHR-01 is now completely free of the 1200.

SHR-13 SPEAKER OUTPUT BOARD

To remove SHR-13 SPEAKER OUTPUT BOARD:

1.

Disconnect the 3-pin connector from P1301.

2. With a 1/2-inch nutdriver or wrench, remove the nuts holding

the speaker output jacks to the rear panel.

3.

Unsolder the leads from AA and AB.

4.

The SHR-13 board is now free of the 1200.

B1 FAN

To remove the fan:

1.

Remove the four screws, nuts, and starwashers at the four

corners of the fan grille. This frees the fan from the rear
panel.

2. Unsolder the black fan leads from pins AE and AG on SHR-14.

3.

If necessary to remove the fan from the 1200, slide the fan

leads out of the insulating tubing and separate the fan from
the unit.

For access to or replacement of any of these parts, turn
the 1200 on its side (power transformer down) and remove the
four Phillips screws that hold the rear panel to the chassis
bottom. The rear panel then can be separated sufficiently from
the chassis bottom to permit access to these boards and
components.

SHR-10 INPUT-OUTPUT BOARD

To remove SHR-10, use a 1/2-in. nutdriver to remove the nuts
on the five phone jacks. Carefully pull the board straight back
until the connectors are free of the rear panel. To separate the
board completely from the rear panel, remove the 6-pin and
4-pin connectors from P1001 and P1002. Unsolder the green
and red leads from the Phantom Power switch, and unsolder
from SHR-10 the yellow lead that connects AC on SHR-10 to
AA on SHR-01. SHR-10 can now be completely separated from
the 1200.

SHR-03 AUX/MIC BOARD

To remove SHR-03, disconnect the four connectors from AA,
AB, BA, and BB to P201 and P202 of SHR-02 and from AC, AD,
BC, and BD to P102 and P104 of SHR-01. Remove the four
Phillips screws that hold the switches to the rear panel; SHR-03
can be completely separated from the 1200.

CAUTION

When replacing the fan, be sure to slide the leads through
the insulating tubing before soldering them to the pins on

SHR-14.

S3 PHANTOM POWER SWITCH

Remove the two screws that fasten the Phantom Power Switch

to the rear panel. This will free the switch from the panel. to

separate the switch completely from the 1200, unsolder the red
and green leads from the switch terminals.

FRONT-PANEL BOARDS AND COMPONENTS

The following printed wiring boards and components are

mounted on the front panel.

SHR-04 CHANNEL BOARD (6)
SHR-05

MASTER CONTROL BOARD

SHR-07 HEADPHONES CONTROL BOARD
SHR-06
SHR-09
SHR-08

S2

HEADPHONES OUTPUT BOARD
LIMITER BOARD
INDICATORS BOARD
POWER ON/OFF SWITCH

7

SHR-04 CHANNEL BOARD

The SHR-04 Channel Boards are assembled and installed in

pairs. Therefore, SHR-04s for Channel 1 and Channel 2 constitute

one pair, those for Channel 3 and Channel 4 constitute another

pair, etc. To remove any pair of Channel Boards:

SHR-09 LIMITER BOARD

To free SHR-09 LIMITER BOARD from the Mounting Panel,
remove from the front of the panel the two Phillips screws that
attach the Limiter Switch to the panel. This frees the board from

the panel.

1.

Remove the control knobs by pulling them off the shafts.

2.

Remove the two flat-head Phillips screws that hold the Channel
Board Assembly in place. One screw is attached to the top of
the front panel ledge, the other to the chassis bottom.

3.

Disconnect the Channel Bus Connector from the top of each
of the two Channel Boards.

4.

Disconnect the 3-pin connector (coming from SHR-01 Input

Board) from the bottom of each of the two SHR-04 Channel
Boards.

5.

Pull the Channel Board Assembly horizontally backward to
free the control shafts from the front panel; the Assembly is

now free of the 1200.

FRONT MOUNTING PANEL

The Front Mounting Panel must be freed from the Front Panel

in order to work on or remove SHR-05 MASTER CONTROL

BOARD, SHR-06 HEADPHONES INPUT BOARD, SHR-07

HEADPHONES CONTROL BOARD, SHR-09 LIMITER BOARD,
SHR-08 INDICATORS BOARD and the Power On/Off Switch
from the 1200. To remove the Mounting Panel:

1.

Remove the two flat-head Phillips screws from the front

panel ledge above the Mounting Panel.

2.

Rest the 1200 on its side with the fan and mounting panel
upwards.

3.

Remove the top three Phillips screws holding the front panel
to the chassis bottom. Leave the bottom screw (below Channel

1) in place. (This will permit swiveling the front panel far
enough away from the chassis to allow the Mounting Panel
to be freed from the 1200 after other required disconnections

have been made.)

4.

Remove the knobs from the control shafts of the Master and
Headphones Controls.

5.

Disconnect the 3-pin connector from P701 on the HEAD-

PHONES CONTROL BOARD.

6.

Disconnect the 3-pin connector from P601 on the HEAD­PHONES OUTPUT BOARD.

7.

Disconnect the CHANNEL BUS connector from P501 at the
top of the MASTER CONTROL BOARD and disconnect 8-,
4-, and 5-pin connectors from P502, P503, and P504 at the

bottom of the MASTER CONTROL BOARD.

IMPORTANT:

Mark all connectors before removing them so

that they can be reconnected correctly.

8.

Loosen the cable tie that holds the cable harness to the hole

in the outside bottom of SHR-05.

9.

Swivel the front panel away from the chassis bottom enough
to permit pulling the control shafts out of the front panel and

partially freeing the Mounting Panel from the 1200. (The

panel is still connected to the 1200 by the transformer leads

connected to the On/Off switch.) From this position it is

possible to remove or work on boards SHR-05, -06, -07,

-08, and -09.

SHR-05 MASTER CONTROL BOARD

To remove SHR-05 MASTER CONTROL BOARD from the

Mounting Panel:

1.

Remove the control knobs.

2.

Use a nutdriver or wrench to remove the nuts holding the
control shafts to the Mounting Panel.

3. To free the board, pull the shafts back out of the panel.

SHR-06 HEADPHONES OUTPUT BOARD AND SHR-07 HEAD-

PHONES CONTROL BOARD

SHR-06 and SHR-07 are connected together by a soldered­in-place 4-conductor ribbon cable. If it is not necessary to
replace the cable, either remove both boards (if desired to free
one of them completely from the 1200), or only remove one (if

freeing the assembly from the 1200 is not essential).

To remove SHR-07 HEADPHONES CONTROL BOARD, remove

the 7/16-inch nut that holds the control shaft to the Mounting

Panel. This permits the board to be freed from the panel (although
it is still connected via the ribbon cable to SHR-06 HEADPHONES

OUTPUT BOARD).

To remove SHR-06 HEADPHONES OUTPUT BOARD, remove

the 1/2-inch nut that holds the phone jack to the Mounting

Panel. This permits the board to be freed from the Panel.

SHR-08 INDICATORS BOARD

Remove the two Phillips screws holding SHR-08 to the back
of the Mounting Panel. Pull the board back from the panel to
remove the LEDs from their holes and to free the board.

S2 ON/OFF SWITCH

To remove the On/Off Switch from the Mounting Panel:

1.

Pull the switch button off the switch control shaft.

2.

Remove the two Phillips screws that hold the switch to the

panel.

3.

Unsolder the red and black transformer leads from the switch.

A1200MX INPUT EXPANSION MODULE

The A1200MX is an optional input expansion module kit that

provides two additional input channels to the 1200. A maximum

of two A1200MXs can be added to the 1200 for a total of 10
inputs. The A1200MX consists of an input connector module

(SHR-15 and SHR-16), an input transformer module (SHR-17),

a channel control module (two SHR-04s), control knobs, and
hardware.

The A1200MX circuitry is identical to the input circuitry of the
other six input channels. Servicing can be accomplished in the
same manner. Printed wiring board drawings are provided with
the service drawings.

CHECKING ACTIVE COMPONENTS

Integrated circuits can be checked without removing them
from their circuit board. Measure the input, output and power
supply voltages as shown on the applicable circuit diagram.

Defective transistors and diodes can be located by use of a
standard ohmmeter such as a Simpson 260. Polarity of the
ohmmeter must be verified before these checks are made; all
resistance measurements are made with the power off in the
circuit under test.

With a known diode orientation, measure the diode resistance

in the forward and reverse directions. The lowest meter reading
will establish the probe at the cathode end (schematic symbol
arrow points to cathode) as the “minus” probe while the other
probe will be “plus.” (Some ohmmeters are not polarized in this
manner with relation to “volts plus probe” and “volts minus
probe.“) With the ohmmeter “plus” probe on the anode end of a
diode, and the “minus” probe on the cathode end, the ohmmeter
should be read approximately 2000 ohms or less. With the
meter probes reversed, a reading of about 10,000 ohms or
more should be obtained. If either of these conditions is not

met, one lead should be unsoldered from the circuit and the test

repeated. If the results are identical, the diode should be replaced.

8

To check LEDs, connect the cathode (notch or flat on flange,

tab on lead or short lead) of the LED to the negative terminal of a

standard 9 V transistor battery. Connect the positive battery

terminal through a 4.7 k resistor to the LED anode. Replace any

LED that does not light.

CAUTION

Do not check LEDs with an ohmmeter. The LEDs may be
damaged or erroneous readings may be obtained.

To check transistors, the ohmmeter should be set to the 100­or 1,000-ohm scale. Transistors must be removed from the
circuit before testing. If all conditions in the following table are
met, the transistor may be considered free of any major defect;
if any of the following conditions are not met, the transistor
should be replaced. See Figure 3 for active component lead
codes.

OHMMETER CONNECTlON

“Plus” Lead
Collector

Emitter
Collector
Emitter Base
Base
Base

“Minus” Lead Transistor
Emitter

Collector
Base High Low

Collector
Emitter Low High

OHMMETER READING

NPN PNP

High High
High High

High Low
Low

Transistor

High

FERRITE BEADS

All low-impedance microphone connectors contain ferrite
beads (L101-L112, SHR-01). Be sure to replace any ferrite
beads removed during servicing.

SERVICE ILLUSTRATIONS

Immediately following the parts list on the pages that follow

are printed wiring board foil and legend drawings, and circuit
diagrams. Once a board has been located through the parts
location photo (Figure 1), the components on that board can be
located from the board drawing. The function of the part is
shown on the relevant circuit diagram.

OPTIONAL ACCESSORIES

The following optional accessories are designed for use with
the Shure 1200 AUDIOMASTER Powermixer.

Carrying Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1200C

Input Expansion Module (2 channels,

2 each HI Z and LO Z inputs . . . . . . . . . . . . . . . . A1200MX*

Speaker Cable, 15 m (50 ft), with phone plugs . . . . . . A50SC

240 V Conversion Kit . . . . . . . . . . . . . . . . . . . . . . . . . RKC209*

Line Matching Transformer (LO Z to HI Z) . . . . . . . . . . . A95UF

Phono Preamplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . M64A

*For installation by qualified service personnel only.

9

REPLACEMENT PARTS LIST

The following list provides information on replacement parts for the Shure Model 1200 AUDIOMASTER Powermixer. Shure part numbers
are given for all parts and, where available, manufacturer’s name and part number for acceptable equivalents in parentheses following the
part description (note that for optimum performance, only direct replacement parts should be used).

NOTE: Carbon film resistors shown in this parts list are rated at 0.2 watts. Standard 1/8-watt resistors should only be used as
replacements if circuit power requirements are not exceeded. Standard 1/4-watt resistors can only be used if they are physically mounted
in a vertical position.

NOTE: In early production, PC Board Assembly SHR-14 contains the following legend error: Capacitor C1423 is marked “+” on the

wrong lead. Note the position of C1423 and replace (if necessary) according to the part, not the legend.

REFERENCE DESIGNATION

A1
B1
C401, C702, C1405, C1408
C402, C410-C411, C413, C508, C509
C404
C407, C503
C408-C409, C501-C502, C1410
C412, C1411, C1415
C506, C510-C511, C1414
C701
C1006
C1101
C1103
C1104, C1113
C1105, C1107
C1106
C1108
C1109, C1112
C1110-C1111
C1201
C1301
C1401
C1403
C1406, C1412-C1414
C1407
C1417-C1418
C1419
C1420-C1421
C1422-C1423
C1424-C1425
C1426-C1428
D401-D404, D701-D702, D1401-D1418
D405
D801-D802
D803
D804
D1101
D1102-D1105
D1106-D1107, D1419-D1421
D1422
D1423
D1424
F1
F1401-F1402
F1403-F1404
J1
J101-J106
J201-J206, J1001-J1005
J601, J1301-J1302
L101-L112
L1101
MP1
MP2
MP3
MP4
MP5

SHURE

PART NO.

803039FK
802641FK
707471FK
707416FK
707425FK
707707FK
707725FK
707439FK
707424FK
800660FK
707351FK
707344FK
707328FK
707358FK
802602FK
707316FK
707350FK
708009FK
707629FK
707315FK
802600FK
707714FK
707571FK
707416FK
707705FK
707438FK
707329FK
707322FK
707354FK
802599FK
802605FK
800625FK
802594FK
800633FK
802596FK
802597FK
706541FK
802593FK
706306FK
706319FK
706323FK
706322FK
713642FK
802634FK
784129FK
802633FK
802629FK
713373FK
784104FK
784108FK
802625FK
788427FK
802579FK
802580FK
802581FK
802582FK

DESCRIPTION

Reverb Pan
Fan
Capacitor, Electrolytic, 0.22 µF, 50 V (Nichicon UKB1HR22KAA)
Capacitor, Electrolytic, 22 µF, 16 V (Nichicon UKB1C100KAA)
Capacitor, Electrolytic, 10 µF, 25 V (Nichicon UKB1E100KAA)
Capacitor, Mylar, 0.0015 µF (Panasonic ECQ-B1H152JZ)
Capacitor, Mylar, .047 µF (Panasonic ECQ-V1H473JZ)
Capacitor, Electrolytic, 1 µF, 50 V (Nichicon ULB1H010MAA)
Capacitor, Electrolytic, 4.7 µF, 25 V (Nichicon ULB1H4R7MAA)
Capacitor, Electrolytic, 10 µF, 50 V (Nichicon ULB1H100MAA)
Capacitor, Electrolytic, 100 µF, 50 V (Nichicon ULB1H101MPA)
Capacitor, Electrolytic, 1 µF, 50 V (Nichicon ULB1H010MAA)
Capacitor, Electrolytic, 47 µF, 25 V (Nichicon ULB1E470MAA)
Capacitor, Electrolytic, 10 µF, 63 V (Nichicon ULB1J100MAA)
Capacitor, Ceramic, 10 pF, 500 V
Capacitor, Electrolytic, 22 µF, 16 V (Nichicon UKB1C100KAA)
Capacitor, Electrolytic, 47 µF, 50 V (Nichicon ULB1H470MAA)
Capacitor, Ceramic, 100 pF, 100 V
Capacitor, Mylar, .1 µF (Panasonic ECQ-V1104JZ)
Capacitor, Electrolytic, 10 µF, 16 V (Nichicon UKB1C100KAA)
Capacitor, Mylar, .047 µF, 100 V (Sprague 225P47391WD3)
Capacitor, Mylar, 0.0056 µF (Panasonic ECQ-B1H562JZ)
Capacitor, Bipolar Electrolytic, 10 µF, 16 V (Panasonic ECE-A1CN100S)
Capacitor, Electrolytic, 10 µF, 16 V (Nichicon UKB1C100KAA)
Capacitor, Mylar, .001 µF (Panasonic ECQ-B1H102JZ)
Capacitor, Electrolytic, 0.47 µF, 50 V (Nichicon UKB1HR47KAA)
Capacitor, Electrolytic, 100 µF, 25 V (Nichicon ULB1E101MAA)
Capacitor, Electrolytic, 1000 µF, 16 V (Nichicon ULB1C102MRA)
Capacitor, Electrolytic, 470 µF, 50 V (Nichicon ULB1H471MRA)
Capacitor, Electrolytic, 10,000 µF, 63 V
Capacitor, Ceramic, .01 µF, 500 V
Diode (RCA SK3100)
LED, Red (RCA SK2022/3022)
LED, Red (RCA SK2022/3022)
LED, Yellow (RCA SK2021/3021)
LED, Green (RCA SK2024/3024)
Diode, Zener (RCA SK24A)
Diode (RCA SK3100)
Diode (RCA SK3311)
Silicon Rectifier (RCA SK3647)
Silicon Rectifier
Silicon Rectifier
Fuse, 5 A, 250 V (Littelfuse 312005)
Fuse, 0.75 A, 250 V (Littelfuse 312.750)
Fuse, 8 A, 250 V (Littelfuse 312008)
Outlet, Unswitched AC
Connector, XLR-type Receptacle, 3-pin (Cannon XLB-3-31PC)
Phone Jack, 2-Circuit
Headphone Jack, 3-Circuit
Ferrite Bead
Coil, 4.6 µH
Rubber Foot
Knob, Green, Bass
Knob, Green, Treble
Knob, Black
Knob, Gold

10

REFERENCE DESIGNATON

MP6
MP7
MP8
MP9
MP10
P1003-P1004
P1401
Q501, Q1110, Q1403
Q1101, Q1114
Q1102
Q1103-Q1104
Q1105,Q1109
Q1106
Q1107-Q1108
Q1111
Q1112-Q1113
Q1401-Q1402, Q1404
Q1405
Q1406
R101-R106
R201-R206, R405, R520, R522,

R1404, R1415, R1445, R1452
R301, R304, R514
R302, R305
R303, R306, R407, R414, R416, R503,

R513, R1401, R1412, R1423,

R1426-R1427, R1430
R401, R518
R402
R403
R404, R409-R410, R502, R504,

R512, R519, R602
R406, R408, R505-R506
R411, R1410, R1422, R1424, R1448-R1449
R412, R1006, R1409, R1420-R1421,

R1433, R1435-R1438, R1443, R1446,

R1451, R1458
R413, R1419, R1453
R415, R523, R601, R704, R1414,

R1417-R1418, R1425, R1429, R1442,

R1444, R1447
R501, R511
R507
R508, R515, R1428
R509, R516-R517
R510
R521, R1001-R1005, R1413,

R1431-R1432, R1459
R603-R605
R701, R703
R702
R1101
R1102, R1104
R1103, R1112, R1201
R1105
R1106-R1108
R1109
R1110
R1111
R1113
R1114
R1115
R1116
R1117
R1118-R1119
R1120, R1122
R1121, R1123
R1124-R1125

SHURE

PART NO.

802583FK
802584FK
802585FK
802587FK
802642FK
802628FK
711080FK
706102FK
706146FK
800412FK

802590FK
801798FK
706156FK
802591FK
706155FK
802592FK
706537FK
706139FK
706147FK
802610FK

801057FK Resistor, 4.7 K
801059FK Resistor, 6.8 K
801068FK Resistor, 39 K

801065FK
802607FK
801075FK
801076FK

801061FK
801058FK
801081FK
801073FK

801072FK Resistor, 82 K

801069FK
801062FK

801055FK

801077FK
801041FK
803041FK

801053FK
802614FK
802815FK
803042FK
708857FK
708842FK
708845FK
708835FK
708850FK
708906FK
708934FK
802617FK
803043FK
708838FK
708836FK

802616FK

802610FK
708849FK
708854FK

708840FK
802613FK

Knob, Red
Knob, Blue
Knob, White
Fan Grille, Front Panel

Fan Grille, Rear Panel
Connector, Receptacle, 2-pin
Connector, Receptacle, 8-pin
Transistor, PNP (RCA SK3932)
Transistor, Dual, NPN (RCA SK9427)
Transistor, Dual, FET
Transistor, Power, PNP (RCA SK9042) (requires 802681FK insulator)
Transistor, NPN
Transistor, NPN (RCA SK9118)
Transistor, Power, NPN (requires 802639FK insulator)
Transistor, PNP (RCA SK9363)
Transistor, Power, PNP (requires 802639FK insulator)
Transistor, FET
Transistor, NPN (RCA SK9137)
Transistor, PNP (RCA SK9138)

Resistor, 1.8 K

Resistor, 22 K
Resistor, 2 K, 2%
Resistor, 150 K
Resistor, 180 K

Resistor, 10 K
Resistor, 5.6 K
Resistor, 470 K
Resistor, 100 K

Resistor, 47 K
Resistor, 12 K
Resistor, 3.3 K
Resistor, 220 K
Resistor, 220
Resistor, 43 K (Early Production); 30 K (Later Production)

Resistor, 2.2 K
Resistor, Metal Oxide Film, 220, 1 W
Resistor, 13 K, 1%
Resistor, 680, 2%
Resistor, 47 K
Resistor, 2.7 K
Resistor, 4.7 K
Resistor, 680
Resistor, 12 K
Resistor, 1.8 K, 2%
Resistor, 47 K, 2%
Resistor, Metal Oxide Film, 5.6 K, 2 W
Resistor, Metal Oxide Film, 68, 1/2 W
Resistor, 1.2 K
Resistor, 820
Resistor, Metal Oxide Film, 3.9 K, 2 W
Resistor, Metal Oxide Film, 1.8 K, 1/2 W
Resistor, 10 K
Resistor, 27 K
Resistor, 1.8 K
Resistor, Metal Oxide Film, 100, 1 W

11

DESCRIPTION

SHURE

REFERENCE DESIGNATION

R1126-R1127
R1128
R1301
R1402
R1403, R1454
R1406-R1407
R1408
R1411
R1416
R1434
R1439
R1440, R1455
R1441
R1450
R1456
R1457
R1460
R1461-R1462
S1
S2
S3
S301-S302
S901
SHR-01
SHR-02
SHR-03
SHR-04
SHR-05
SHR-06
SHR-07
SHR-08
SHR-09
SHR-10
SHR-11

SHR-12
SHR-13
SHR-14
T1
T101-T106
U401-U402, U501-U504, U701,

PART NO.

802612FK
708853FK
710041FK
801064FK
801080FK
800190FK
801033FK
801085FK
801089FK
801063FK
802609FK
801070FK
801051FK
801045FK
800749FK
802611FK
709314FK
802615FK
802630FK
802631FK
802632FK
801599FK
784110FK
235901FK
235902FK
235903FK
235904FK
235905FK
235906FK
235907FK
235908FK
235909FK
235910FK
235911FK
235912FK
235913FK
235914FK
803474FK
802626FK
706077FK

U1401-U1407

U1201
U1408
U1409
U1410
V1401
VR401
VR402, VR502
VR403, VR405, VR701
VR404
VR501, VR504
VR503
VR1101-VR1102
VR1103
VR1201
VR1401
W1
W2
W3
W4
XF1

+ May not exhibit the low-noise characteristics of the original part.

802588FK
802589FK
706097FK
706098FK
802598FK
802620FK
802622FK
802619FK
802621FK
802623FK
802624FK
802618FK
802681FK
800030FK
710138FK
802638FK
908575FK
908580FK
800618FK
802636FK

DESCRIPTION

Resistor, Ceramic, Dual, .22, 5 W
Resistor, 22 K
Resistor, Ceramic, 10, 5 W
Resistor, 18 K
Resistor, 390 K
Resistor, 22, 1/2 W
Resistor, 47
Resistor, 1 M
Resistor, 2.2 M
Resistor, 15 K
Resistor, 51 K, 2%
Resistor, 56 K
Resistor, 1.5 K
Resistor, 470
Resistor, Metal Film, 100 K, 1%
Resistor, Metal Film, 36 K, 1%
Resistor, Metal Oxide Film, 39, 1/2 W
Resistor, Metal Oxide Film, 47, 2 W
Switch, Voltage Selector, DPDT
Switch, On/Off, SPST
Switch, Phantom Power, SPST
Switch, Slide, DPDT
Switch, Slide, DPDT
Printed Wiring Assembly, Lo-Z Input
Printed Wiring Assembly, Hi-Z Input
Printed Wiring Assembly, Aux/Mic
Printed Wiring Assembly, Channel
Printed Wiring Assembly, Master Control
Printed Wiring Assembly, Headphones Out
Printed Wiring Assembly, Headphones Control
Printed Wiring Assembly, Indicator
Printed Wiring Assembly, Limiter
Printed Wiring Assembly, Input/Output
Printed Wiring Assembly, Power
Printed Wiring Assembly, Sensor
Printed Wiring Assembly, Speaker Output
Printed Wiring Assembly, Main
Transformer, Power
Transformer, Mic Input
IC, Quad Op Amp (RCA SK3465+)

IC, Thermal Sensor
IC, Voltage Regulator (Motorola MC7824)
IC, Voltage Regulator, Positive (Motorola MC7815)
IC, Voltage Regulator, Negative (Motorola MC7915)
Opto-Isolator
Potentiometer, Log, 100 K
Potentiometer, Dual, Linear, 50 K
Potentiometer, Log, 10 K
Potentiometer, Linear, 20 K
Potentiometer, Log, 100 K
Potentiometer, Linear, 10 K
Potentiometer, Linear, 100
Potentiometer, Linear, 1 K
Potentiometer, Linear, 47 K
Potentiometer, Linear, 5 K
Power Cable and Plug, 3 m (10 ft), 3-Conductor
Channel Bus Cable, Ribbon, 8-Conductor, with Connectors
Cable, Ribbon, 5-Conductor
Cable, Ribbon, 4-Conductor
Rear Panel Fuseholder

12

BLOCK DIAGRAM

LEAD CODES

15

16

17

18

19

20

21

CIRCUIT DIAGRAM-1

(SHR-01, SHR-02, SHR-03, SHR-04)

22

CIRCUIT DIAGRAM-2

(SHR-05, SHR-07, SHR-08, SHR-10)

23

CIRCUIT DIAGRAM-3

(SHR-09, SHR-12, SHR-14)

24

CIRCUIT DIAGRAM-4

(SHR-06, SHR-11, SHR-13, SHR-14)