Clear-Com KB-212 User manual

KB-212
SPEAKER STATION
USER MANUAL

Clear-Com Intercom Systems KB-212 Speaker Station
© Clear-Com Intercom Systems 2000 1Rev. B
Introduction
Congratulations and thank you for choosing this Clear-Com product.
The KB-212 Speaker Station is a powerful, yet user-friendly unit that can
serve as a versatile intercom station.
Please read this manual completely to better understand the functions of
these products. For questions not addressed in this manual, contact the
dealer or Clear-Com directly. Clear-Com applications support and service
people are ready to help.
Description
The Clear-Com PL-Pro™ KB-212 speaker station is designed for use in
theatres, live performances, industrial environments, and small television
facilities. It features speech intelligibility, even in high noise levels, and can be
customized through its programmable options.
Local or remotely controlled talking or listening is selectable and allows either
hands-on or hands-free operation. The talk button operates in momentary
mode. The integral microphone and speaker offer half-duplex communication.
The KB-212 offers both visual and audible call signaling to attract the
attention of operators.
A balanced program input allows the monitoring of external audio through the
speaker. This program input can also be used as a paging function.
The integral speaker’s volume level can be adjusted using a front-panel knob.
An internal control allows setting a minimum speaker level. An automatic
speaker switching circuit will quiet the speaker when the talk button is
activated.
The KB-212 receives 30-VDC power from the Clear-Com intercom line. The
unit mounts either in a standard four-gang electrical outlet box or in an
optional Clear-Com V-Box. The extra-thick front panel and compact, surface-
mount circuitry results in a reduced size and lighter weight package that
maintains Clear-Com ruggedness. The intercom channel connects to a plug-
on screw terminal strip. Male and female three-pin XLR connectors are
provided on the optional V-Box to offer a through connection to the intercom
channel.
Although the optional EB-4W daughter board module allows this unit to
function on a TW line, the unit’s operation will remain single channel. Also, the
EB-4W 4-Wire daughter board module is available to allow long-distance
connections using separate pairs of wires for send audio and receive audio.
The KB-212 is compatible with all Clear-Com Party-Line intercoms.

KB-212 Speaker Station Clear-Com Intercom Systems
Rev. B 2© Clear-Com Intercom Systems 2000
Quick Start
1. Unpack the unit and inspect it for any damage that may have
occurred during shipping.
2. Set the Option switches to the default (toward the front panel)
position.
3. Connect the intercom lines.
4. Install the KB-212 into the four-gang outlet box or V-Box. (For
additional information, refer to the Clear-Com PL-Pro™System
Installation Manual.)
5. Set Listen Levels. (Refer to “6—Intercom Level Control” on
page 4.)
6. The speaker station should now be operating properly.
7. Read the rest of this manual for further information.

Clear-Com Intercom Systems KB-212 Speaker Station
© Clear-Com Intercom Systems 2000 3Rev. B
Operation
Normal operation of the KB-212 Speaker Station only requires access to the
front-panel controls. The controls located elsewhere on the unit are intended
to be set-and-forget in nature For intercom operation, set the Listen level
control to the desired level and press the Talk button when talking.
Front Panel
The controls, indicators, and connectors on the KB-212 front panel are shown
in Figure 1 on page 3 and are described by the following text.
FIGURE 1: Front Panel
1—Talk Button
The Talk button activates the microphone feed to the intercom channel. The
Talk button has a momentary action.
pro
KB-212
S p e a k e r
S t a t i o n
PL
Intercom Level
Call
Talk
Program Level
56
7
48
Mic
1 2
3

KB-212 Speaker Station Clear-Com Intercom Systems
Rev. B 4© Clear-Com Intercom Systems 2000
2—Talk Lamp
The Talk lamp lights when the microphone feed to the intercom channel is on,
whether this is activated locally by the Talk button or remotely from another
station using the call signal.
3—Call Button
Pressing the Call button will send a call signal and cause all the call lights on
other stations on the intercom channel to light.
4—Call Lamp
The Call lamp will light while the Call button is pressed, or when a call signal
is on the intercom channel.
5—Tone Alert
An audible tone alert can sound when a call signal is received on the intercom
channel. This can be useful when the operator's attention has been drawn
away from the KB-212 indicator panel. The audible tone alert level can be
adjusted or turned off by an internal control. The Tone Alert will not sound if a
call signal is originated at the KB-212 station.
Note: This feature is automatically turned off if the operating mode of the KB-
212 is set to any setting other than Normal.
6—Intercom Level Control
Turn this control to set the speaker’s required listen level. This control does
not affect the Tone Alert level or the Program Input level.
7—Program Level Control
Adjust the Program Level control to set the program audio level heard in the
panel speaker.
Note: Forcing the trimpots past their stop points will damage them.
8—Integral Microphone
The microphone for the KB-212 is built into the front panel.
Internal Adjustments and Connections
The controls and connectors inside the KB-212 are shown in the following
figure and described by the following text. The controls can be accessed
without completely removing the panel from its wall box or V-Box enclosure
by removing the top two screws and loosening the bottom two screws a few
turns. The panel can then be leaned out from the wall to make the controls
accessible as shown in the lower view of Figure 2 on page 5.

Clear-Com Intercom Systems KB-212 Speaker Station
© Clear-Com Intercom Systems 2000 5Rev. B
FIGURE 2: Internal Controls
9—Call Alert Tone Level Control
This control adjusts the volume of the Call Alert Tone sound. This is normally
adjusted when the system is set up and shouldn’t need to be adjusted during
normal operation. This feature can be disabled by turning the control fully
counterclockwise.
10—Minimum Volume Control
This control adjusts the minimum setting of the Intercom Level control on the
front panel. Setting this control can prevent people from inadvertently turning
the intercom level all the way down. This is normally adjusted when the
system is set up and shouldn’t need to be adjusted during normal operation.
This feature can be disabled by turning the control fully counterclockwise.
P3 Must be
installed if
no option
P1 Must be
installed if
no option
1 2 3
12
13
109
View from top
of KB-212
Front Panel
14
11

KB-212 Speaker Station Clear-Com Intercom Systems
Rev. B 6© Clear-Com Intercom Systems 2000
11—Option Switches
Three Option switches are provided. They should be configured when the
system is set up, but are not changed in normal operation.
Note: The ON position of each switch is toward the circuit board and the OFF
position is toward the front panel. The function of these switches is as follows:
• Internal Microphone Gain (S1-1)— This switch determines the
microphone’s sensitivity. When the switch is in the ON position, talking
should be done within 2 ft. of the front panel. If it is necessary to talk
from a greater distance, the switch should be turned OFF. The default
position of this switch is in the ON position.
• Operating Mode (S1-2 and S1-3)—These switches work together to
define the operating mode of the KB-212. In modes other than Normal,
the call signal from other stations on the same channel activates the
KB-212. Refer to the following table:
• The default position of these switches is in the OFF position for Normal
mode, which is the only mode in which the Call Alert Tone functions
operate. In other modes, the Call Alert Tone is automatically disabled to
avoid interference with operation.
Note: Only Normal mode may be used when the EB-4W 4-Wire Option
Module is installed.
Mode S1-2 S1-3 Description
Normal OFF OFF Speaker is on
Mic is activated by the Talk button
Remote Page OFF ON Speaker turns on by remote call signal control
Mic is activated by the Talk button
Remote Listen ON OFF Speaker is on
Mic is activated by remote call signal control or by the
Talk button
Remote Listen-Page ON ON Speaker turns on by remote call signal control or by
the Talk button
Mic is normally on
Table 1: KB-212 Operating Mode Options

Clear-Com Intercom Systems KB-212 Speaker Station
© Clear-Com Intercom Systems 2000 7Rev. B
12—Intercom Line Connection
The KB-212 contains a five-terminal, plug-on connector for intercom line
connection. This connector is intended to be unplugged from the circuit board
when connecting the intercom line, and then plugged back on when the wiring
is completed. The connections for each pin are visible on the circuit board
when the connector is unplugged. The pinout of this connector is as follows:
• Pin 1—(NC)
• Pin 2—(NC)
• Pin 3—Channel A Audio
• Pin 4—Power (30 VDC)
• Pin 5—Ground (Shield).
FIGURE 3: Intercom Line Connector Wiring
13—Program Input
A three-terminal, plug-on connector provides the program input to the station.
Program is fed to the speaker. This level is controlled by the Program Level
control. The Program Input accepts a balanced or unbalanced line-level audio
signal from -20 dBv to +10 dBv. If this input is connected to the stage
announce (SA) output of a Main Station it can be used as a paging input.
Since the level of this input is independently adjustable from the intercom
audio volume, it can be used to override the intercom audio in all modes
except Remote Listen-Page. The program input is also independent of the
Mode setting. The pinout of the Program Input connector is as follows:
• Pin 1—Ground (Shield)
• Pin 2— + Signal
• Pin 3— - Signal.
23
1
KB-212 Intercom
Connector
XLR
Connector
Channel A
Pin 1

KB-212 Speaker Station Clear-Com Intercom Systems
Rev. B 8© Clear-Com Intercom Systems 2000
FIGURE 4: Program Input Connector Wiring
14—Option Board Jumpers
The two jumper plugs P1 and P3 must be installed when optional modules are
not used. When the optional EB-4W or EB-TW Modules are used, both P1
and P3 must be removed. Save these jumper plugs for possible future use.
Note: The KB-212 will not operate without either the jumper plugs or the
optional modules installed.
23
1
g
KB-212 Program
Input Connector XLR Connector
Pin 1

Clear-Com Intercom Systems KB-212 Speaker Station
© Clear-Com Intercom Systems 2000 9Rev. B
FIGURE 5: KB-212 Block Diagram
Troubleshooting
•System does not operate. The Talk Light does not come on when
Talk button is pressed.
Scenario 1
No intercom connection to the KB-212. If the EB-4W 4-Wire Option Module is
connected, no AC power to the KB-212.
EQ/
LIM
Talk
Min
Vol
Call
Light
Call
Intercom
Volume
TW Option
Intercom
Speaker
Power
(NC)
Call Send &
Receive
Microprocessor
Talk
Balanced
Program
Input
Speaker
Mute
Program
Mute
Mic Mute
Common
+30 VDC
Ground
Operating
Mode
Options
Mic Gain
Program
Level
Call Alert
Tone Level
4-Wire
Input
4-Wire
Output
2-Wire / 4-Wire
Select
Rectifier
16 VAC
Power
4-Wire
Option
Panel Mic

KB-212 Speaker Station Clear-Com Intercom Systems
Rev. B 10 © Clear-Com Intercom Systems 2000
Solution: Check connections and cable.
Scenario 2
The KB-212 has an internal failure.
Solution: Unit requires servicing.
• System operates incorrectly. The Talk Light does not come on
when Talk button is pressed or stays on until Talk button is
pressed and the Speaker is off when it should be on.
Scenario 1
Operating Mode switches are set incorrectly.
Solution: Refer to the option switch setting section of this manual.
•Speaker does not operate. The Talk Light comes on when Talk
button is pressed.
Scenario 1
Intercom Level knob turned all the way down.
Solution: Adjust control appropriately.
Scenario 2
Speaker plug or wiring has come loose.
Solution: Make sure speaker is connected internally.
Scenario 3
Plug P3 missing on circuit board.
Solution: Plug P3 must be installed in jack J3 if the EB-4W or EB-TW option is
not used.
• Hum or buzz in system
Scenario 1
Inductive pickup caused by close proximity of this speaker station or
connected stations to power lines or transformers.
Solution: Relocate the offending unit or wiring. If the cable run is exceptionally
long, consider adding and using the EB-4W 4-Wire Option Module. (Requires
an additional 4-wire interface at the opposite end of a “long run.”)
•System feedback (Acoustical)
Scenario 1
Intercom Level control at this station or another station is set too high.
Solution: Adjust.

Clear-Com Intercom Systems KB-212 Speaker Station
© Clear-Com Intercom Systems 2000 11 Rev. B
Scenario 2
Channel unterminated.
Solution: Set the Main Station or Power Supply termination switch for the
appropriate channel to the ON position.
Scenario 3
The KB-212’s microphone is too close to an open speaker on the same
channel.
Solution: Change the units’ location.
•Excessive crosstalk
Scenario 1
High DC resistance in ground return.
Solution: Use heavier cable; add additional conductor(s) to ground return. If
the cable run is exceptionally long, consider adding and using the EB-4W 4-
Wire Option Module.
Scenario 2
Multi-channel cable pairs are not individually shielded.
Solution: Replace cable with individually shielded pairs.
•Program signal sounds distorted.
Scenario 1
Program Level control set too high.
Solution: Turn the Program Level control counter-clockwise.
Scenario 2
Overload of Program Input circuit.
Solution: Reduce the gain of the program signal at the source, such as an
audio mixer.
•The call signal does not function.
Scenario 1
Excessive DC loading of intercom line.
Solution: Remove any audio transformers or other equipment that may be
connected across the intercom line. If equipment other than Clear-Com
intercom equipment must be connected to the intercom line, please contact
Clear-Com application or service personnel for information or
recommendations.
Scenario 2
Far too many terminations on the intercom line.
Solution: Check all main stations and power supplies to make sure each
intercom channel is terminated at only one point.

KB-212 Speaker Station Clear-Com Intercom Systems
Rev. B 12 © Clear-Com Intercom Systems 2000
Scenario 3
Plug P1 missing on circuit board.
Solution: Plug P1 must be installed in the J1 jack if the EB-4W or EB-TW
options are not used.
Parts Lists
Parts List for the KB-212 Main PCB
Capacitors
Value Type Volts Tol. Part # Designator
220 uF Aluminum 35V 150021 C5 C18
22 uF Tantalum 16V 150032 C21 C24
4.7 uF Aluminum NP 50V 150087 C13
100 uF Aluminum 35V 150136 C25 C45
22 pF Ceramic Disc SMD 50V 5% 151116 C14
47 pF Ceramic Disc SMD 50V 5% 151120 C7 C19 C30 C36
220 pF Ceramic Disc SMD 50V 5% 151128 C26
390 pF Ceramic Disc SMD 50V 5% 151131 C10
470 pF Ceramic Disc SMD 50V 5% 151132 C17
.0015 uF Ceramic Disc SMD 50V 5% 151138 C11
.0047 uF Ceramic Disc SMD 50V 10% 151156 C27
.01 uF Ceramic Disc SMD 50V 10% 151160 C32 C33 C35 C38 C44
.047 uF Ceramic Disc SMD 50V 10% 151168 C23 C37
.1 uF Ceramic Disc SMD 50V 10% 151172 C3 C4 C12 C15 C29
C39C40 C41 C46 C47
.22 uF Ceramic Disc SMD 50V 10% 151176 C16 C22 C28
.47 uF Tantalum SMD 35V 10% 151184 C31 C34
1 uF Tantalum SMD 16V 10% 151185 C6 C20 C43
4.7 uF Tantalum SMD 16V 10% 151189 C8
10 uF Tantalum SMD 25V 10% 151192 C42
Resistors
Value Power Type Tol. Part # Designator
10 OHM 1/4 Carbon Film 5% 410002 R19 R45
390 OHM 1/4 Carbon Film 5% 410005 R39
1.3K OHM 1/2 Carbon Film 5% 410075 R28
2.2 OHM 1/10 SMD 5% 411181 R27
100 OHM 1/10 SMD 1% 411293 R40
301 OHM 1/10 SMD 1% 411339 R41
432 OHM 1/10 SMD 1% 411354 R15
475 OHM 1/10 SMD 1% 411358 R10
1.00K OHM 1/10 SMD 1% 411389 R29
1.21K OHM 1/10 SMD 1% 411397 R17
1.50K OHM 1/10 SMD 1% 411406 R31
2.00K OHM 1/10 SMD 1% 411418 R14 R38

Clear-Com Intercom Systems KB-212 Speaker Station
© Clear-Com Intercom Systems 2000 13 Rev. B
3.24K OHM 1/10 SMD 1% 411438 R26
4.75K OHM 1/10 SMD 1% 411454 R20
5.62K OHM 1/1O SMD 1% 411461 R18
6.19K OHM 1/10 SMD 1% 411465 R23
8.25K OHM 1/10 SMD 1% 411477 R42
10.0K OHM 1/10 SMD 1% 411485 R8 R44
12.1K OHM 1/10 SMD 1% 411502 R13 R33
20.0K OHM 1/10 SMD 1% 411514 R12 R24 R32
33.2K OHM 1/10 SMD 1% 411535 R43
47.5K OHM 1/10 SMD 1% 411550 R2 R4
68.1K OHM 1/10 SMD 1% 411565 R35 R36
100K OHM 1/10 SMD 1% 411581 R5 R21
121K OHM 1/10 SMD 1% 411589 R22
221K OHM 1/10 SMD 1% 411614 R48
475K OHM 1/10 SMD 1% 411646 R46 R47
1.0M OHM 1/10 SMD 5% 411677 R49
10K OHM X4 SMD DIP Isolated 1% 416016 R1 R7 R9
47K OHM X4 SMD DIP Isolated 1% 416018 R3
100K OHM X4 SMD DIP Isolated 1% 416019 R6
Pot 10K TRIMPOT 470058 R34 R30
Pot 5K TRIMPOT 470063 R37
Pot 5K POT 470081 R25
Diodes and Transistors
Device Description Part # Designator
LED LOW CURRENT GREEN T1 3/4 LED 390021 D8
LED LED, YELLOW, ULTRA BRIGHT T1 3/4 390057 D3
IC LM384 POWER 4W OP AMP 14 PIN 480012 IC5
IC 7805L POS 5V REGULATOR TO-92 PKG 480088 IC10
Diode BAV70 DUAL DIODE COM CATH... SMD 481019 D1 D7
IC 833 DUAL OPAMP... SMD 481023 IC1 IC2 IC8
Transistor 2907A PNP 60V 600MA... SMD 481027 Q2
Diode BAV99 DUAL DIODE... SMD 481033 D2 D5 D6
Transistor MPSA14 DNPN 30V 300MA... SMD 481038 Q4
IC DG444 QUAD CMOS ANALOG SW SMD 481050 IC4
Transistor J175 P-CHANNEL JFET... SMD 481056 Q1
Diode 5.1V 5% ZENER 1/4W... SMD 481061 D4
Transistor MPSA64 DPNP 30V 500MA SMD 481075 Q3
IC MICROPROCESSOR, KB/MR SERIES 710508 IC9
Miscellaneous
Device Description Part # Designator
Connector 5 POS, SCREW TERM. PLUG-IN 5MM 210085 P4
Connector 3 POS, SCREW TERM. PLUG-IN 5MM 210370 P2
Pot SHAFT FOR PIHER POT FIG 3 GREY PT10 240043 R30 R34
Pot PIHER TRIMPOT SHAFT, GREY 240057 R37
Pot KNOB GREY INSERT 240077 R25
Button ROUND MINIATURE BUTTON, BLACK 240081 S2

KB-212 Speaker Station Clear-Com Intercom Systems
Rev. B 14 © Clear-Com Intercom Systems 2000
Button RECT. MINIATURE BUTTON, BLACK 240082 S3
Lens LENS, YELLOW, ROUND FOR T1 3/4 240099 D3
Speaker 2 1/2 IN. SPKR 8 OHM 3.5W 500103
Panel Mic ELECTRET MIC ELEMENT W/PINS 500132
Switch DPDT P.B. MINIATURE W/LONG PLUNGER 510107 S2 S3
Switch DIP SWITCH PIANO 3 POS 510114 S1
RUBBER MIC MOUNT 640027
FIGURE 6: Main PCB Component Layout

© Clear-Com Intercom Systems 2000 15 Rev. B
FIGURE 7: KB-212 Schematic

KB-212 Speaker Station Clear-Com Intercom Systems
Rev. B 16 © Clear-Com Intercom Systems 2000
This page is a place holder.

Clear-Com Intercom Systems KB-212 Speaker Station
© Clear-Com Intercom Systems 2000 17 Rev. B
Technical Specifications
Panel Microphone Pre-Amp
Input Type: Electret
Gain from panel
mic to intercom line: +25 dB, low sensitivity; +31.5 dB high sensitivity
Pre-Amp Response Curve
Frequency Response: 250 Hz to 12 kHz, contoured for intelligibility
Limiter Range: 20 dB
Speaker Amplifier
Speaker Type: 2.5 in. round, 16 ohm
Power Output: 2 W into 16 ohms
Frequency Response: 200 Hz to 15 kHz, ±3 dB
Signal-to-Noise: 75 dB
Gain from intercom line: +37 dB
Distortion: < 0.5% THD at 1 kHz
Speaker Level: 98 dB SPL at 3 ft.
Program Amplifier
(Transformerless, balanced differential input)
Input Level: -20 dBV
Input Impedance: > 100k ohm
Frequency Response: 150 Hz to 15 kHz, ± 3 dB
Power Requirements
Voltage: 30-VDC standard unit; 16 to 18 VAC with 4-Wire Option
Module
Current: 100 mA average
Internal Connectors
Intercom: five-position, plug-on screw terminals
Program: three-position, plug-on screw terminals
AC Power
(4-Wire Option Module): two-position, plug-on screw terminals
Internal Controls
(3) Option switches; (1) Tone Alert Volume control; (1) Minimum Volume Level control

KB-212 Speaker Station Clear-Com Intercom Systems
Rev. B 18 © Clear-Com Intercom Systems 2000
Front Panel Controls & Indicators
(1) Program Level control; (1) Intercom volume control; (1) Talk button; (1) Call button; (1)
Talk LED; (1) Call LED
Environmental
32 to 122 F (0 to 50 C)
Dimensions 8.25 in. W x 4.5 in. H x 1.75 in. D (210 mm x 114 mm x 44 mm)
Weight 1.04 lbs. (0.47 kg)
Notice About Specifications
While Clear-Com makes every attempt to maintain the accuracy of the
information contained in its product manuals, that information is subject to
change without notice. Performance specifications included in this manual
are design-center specifications and are included for customer guidance and
to facilitate system installation. Actual operating performance may vary.
KB-212 Manual P/N 810254
© 2000 Clear-Com Systems
All Rights Reserved

Clear-Com Intercom Systems KB-212 Speaker Station
© Clear-Com Intercom Systems 2000 19 Rev. B
Clear-Com Limited Warranty
The Clear-Com warranty does not cover any defect, malfunction, or failure
caused beyond the control of Clear-Com, including unreasonable or negligent
operation, abuse, accident, failure to follow instructions in the manual,
defective or improper associated equipment, attempts at modification and
repair not authorized by Clear-Com, and shipping damage. Products with
their serial numbers removed or defaced are not covered by this warranty.
This warranty is the sole and exclusive express warranty given with respect to
Clear-Com products. It is the responsibility of the user to determine before
purchase that this product is suitable for the user's intended purpose.
Any and all implied warranties, including the implied warranty of
merchantability are limited to the duration of this express limited warranty.
Neither Clear-Com nor the dealer who sells Clear-Com products is liable for
incidental or consequential damages of any kind.
For your own records fill in the information below:
Model No Serial No.
Date Purchased
Purchased from (dealer)
Address
City State ZIP
Factory Service
All equipment returned for repair must be accompanied by documentation
stating the return address, telephone number, date of purchase, and a
description of the problem.
Note: Do not return any equipment to the factory without first obtaining a
Return Authorization Number.
Send equipment to be repaired to:
Customer Service Department
Clear-Com Intercom Systems
4065 Hollis Street
Emeryville, CA 94608-3505
Telephone: [phone]
Fax: [phone]
Warranty Repairs
If in warranty, no charge will be made for the repairs. Equipment being
returned for warranty repair must be sent prepaid and will be returned
prepaid.