Motorola NMN6227B User manual

, and Motorola are trademarks of Motorola, Inc.
*6881083C60*
Service Manual
68P81083C60-A
PUBLIC-SAFETY
SPEAKER/MICROPHONE
Models: NMN6227B,
NMN6234B, and NMN6236B
I. DESCRIPTION
The NMN6227B, NMN6234B, and NMN6236B Public-
Safety Speaker/Microphones include a speaker, microphone,
push-to-talk (PTT) switch, high/low volume switch, swivel clip,
and cord connector assembly. The NMN6227B, NMN6234B,
and NMN6236B models are all the same, except that the
microphones’ cord lengths are different: NMN6227B is 30”,
NMN6234B is 24”, and NMN6236B is 18”. The public-safety
speaker/microphones also have a threaded antenna jack
located on top of the housing, which accepts any of the
following antennas:
“high,” will equal or exceed the loudness of the radio speaker.
NOTE
The RF connector on the mike head is not wired as
coaxial. Transmit power measurements should read
ZERO at this connector.
The RF connector (J2) on the microphone head is wired
as center and shield shorted together and connected to the
RF coax cable center. The rf coax shield is connected to pcb
ground for best radiation performance.
B. Audio test
The speaker/microphone accessory can be checked for
proper performance by comparison with another new or
known good unit on the radio. Start each of the following two
tests with the new or known good unit on the radio.
1. Microphone - Transmit to a communications monitor
while voicing a tone or the spoken word ‘four.’ The
speaker/microphone should be held at a distance that
causes approximately 3kHz deviation. Repeat these
conditions using the speaker/microphone to be tested.
Good units compare to each other within ±2kHz
deviation.
2. Speaker - Using the communications monitor, generate
an rf signal to the radio. Set the modulation to a 1kHz
tone at 3kHz deviation. Set the high/low switch on the
speaker/microphone to “high.” Set the volume control on
the radio to a loud, yet undistorted position. Without
disturbing any settings, repeat these conditions using the
speaker/microphone to be tested. Good units should
sound equally loud and undistorted. The “low” setting
loudness should compare as above.
C. Antenna test
Refer to Table 1 and verify that the proper antenna is
being used. Use one of the following to conduct this test:
• a communications monitor set to spectrum analyzer is
best,
• a monitor receiver set to threshold squelch, or
• a field strength meter.
Connect a new or known good public-safety microphone
to the radio. Transmit to the equipment using the microphone
PTT by radiating to an input antenna on the equipment at a
distance that causes a mid-scale result. For a receiver set for
threshold squelch, set the squelch to just open when
transmitting. Connect the public-safety microphone for test to
the radio, and transmit at the same distance as above. The
result should compare closely to the known good or new
microphone for field intensity.
© 1995 by Motorola, Inc.
Radio Products Group
8000 W. Sunrise Blvd., Ft. Lauderdale, FL 33322
Printed in U.S.A. 08/95. All Rights Reserved.
TABLE 1. ANTENNAS
Antenna Frequency Description Insulator
Kit Number Color Code
NAE6546 UHF, 403-435 MHz 3" Helical RED
NAE6547 UHF, 435-470 MHz 3" Helical GREEN
NAE6548 UHF, 470-512 MHz 3" Helical BLACK
NAF5042 800 MHz Quarter Wave, Stubby WHITE
NOTES
•The antenna is not supplied with the public safety
speaker/microphone kit, and it must be ordered
separately.
•It is not recommended to use these public-safety
speaker/microphones with vhf radios, since radio
performance is reduced.
•In shipping, a protective rubber seal (Motorola part
number 3205782P01) is inserted in the
microphone’s antenna port. Use this seal to cover
the microphone or radio antenna port when not in
use.
When the speaker/microphone is attached to the radio,
the speaker in the radio is disabled, and the receiver audio is
connected to the accessory speaker. Similarly, the accessory
microphone is connected to the transmitter, and the
accessory PTT switch can now control the PTT function of
the radio. The radio microphone and PTT switch are still
operational, but since the radio speaker is disabled, you can
listen to the received audio only through the accessory
speaker.
II. PERFORMANCE TEST
A. General
The speaker/microphone audio performance is designed
to be similar to that of the radio. The receive audio speaker
loudness, with the high/low switch on the microphone set for

2
III. HANDLING PRECAUTIONS
To avoid damage to circuits, observe the following
handling, shipping, and servicing precautions.
A. Prior to and while servicing a public safety speaker/
microphone, particularly after moving within the service
area, momentarily place both hands on a bare metal,
earth-grounded surface. This will discharge any static
charge your body may have accumulated.
B. Whenever possible, avoid touching any electrically
conductive part of the unit with your hands.
C. Because they contribute to static buildup, avoid
carpeted areas, dry environments, and certain types of
clothing (silk, nylon, etc.) when servicing a unit.
D. All electrically-powered test equipment should be
grounded. Apply the ground lead from the test
equipment to the unit before connecting the test probe.
Similarly, disconnect the test probe prior to removing
the ground lead.
E. If the microphone cartridge is removed from the unit,
place it on a conductive surface, such as a sheet of
aluminum foil which is connected to ground through
100k ohms of resistance.
F. When soldering, be sure the soldering iron is grounded.
G. Prior to replacing circuit components or touching the
microphone cartridge, be sure to discharge any static
buildup. Since voltage differences can exist across the
human body, it is recommended that only one hand be
used if it is necessary to touch the microphone cartridge
and associated wiring.
H. Replacement microphone cartridges should be kept in
conductive packaging until they are placed in the unit.
I. If the microphone has been exposed to water, shake the
unit to remove any residual water from the speaker grille
area. Blow out any residual water from the microphone
grille area before operating the radio; otherwise, the
sound may be distorted until the water has evaporated
from these areas.
IV. MAINTENANCE
Refer to the schematic diagram, the exploded view, and
the parts lists. Every part in the microphone is identified and
illustrated for assistance in removal and replacement.
If disassembly of the public safety speaker microphone
is required, do not reassemble it without doing the following
(numbers in parentheses refer to item numbers in the
exploded view).
•Remove the O-ring gasket (22) from the cover assembly
(16).
•Inspect the seal areas around the housing (1) and the
cover (16) for foreign material which might prevent the
O-ring gasket from sealing properly.
•Inspect O-ring gasket (22) and both cover screw O-rings
gaskets (18). If any of these are split, cracked, or
damaged in any way, discard and replace them.
•If the main printed circuit board (14) is removed, remove
the speaker spacer (27) and inspect the membrane of
the seal pad (28) for tears or holes. If the membrane is
damaged, remove it, being careful to remove all old
adhesive, and replace it with a new seal pad.
NOTE
When placing the seal pad (28), it is critical that
the small seal pad opening be aligned with the
microphone port in the housing.
•Tighten all hardware loosened or removed during
disassembly per the values listed in the Torque
Specifications table. Use the recommended torque
driver (RSX-4043A Rototorq Tool or equivalent).
If necessary, the external surfaces of the remote
speaker microphone may be cleaned with 0.5% solution of
mild dishwashing detergent in water (one teaspoon of
detergent in a gallon of water).
TABLE 2. TORQUE SPECIFICATIONS
TORQUE TORQUE TORQUE
APPLICATION (IN. LBS.) (N•m) BIT NO.
Cover Screws 6 0.68 6680321B78
PC Board Screws 3 0.34 6680321B78
Clip Screws 4 0.45 6680321B78
Toggle Switch Boot 3 0.34 6680370B99
Connector Assembly 3 0.34 6680381B69
Screw
Ear jack Spanner 3 0.34 6680370B89
Antenna Spanner 20 1.13 6680341A61
!
Wearing a conductive wrist strap (Motorola No. RSX-
4015A) will minimize static buildup during servicing.
CAUTION
!
If the aluminum foil is connected directly to
ground, be cautious of possible electrical shock
from contacting the foil and other electrical
circuits at the same time.
WARNING
When wearing a conductive wrist strap, be
careful near high voltage sources. The good
ground provided by the wrist strap will also
increase the danger of lethal shock from
accidentally touching high-voltage sources.
!WARNING

3
REFERENCE MOTOROLA
SYMBOL PART NO. DESCRIPTION
Electrical Parts List TPLF-4195-A
SPEAKER:
LS1 5005213W01 1 3/4"; 28Ω
MICROPHONE:
MK1 5005227J06 Electret
RESISTOR, Fixed: Ω±5%; 1/8W
unless stated
R1, 2 0611077A54 150
R3, 4 Not Used
SWITCH:
S1 3905834K05 Dome, PTT
S2 4005680K04 Toggle
DIODE: See Note
VR1, 2 4880140L14 Zener, 9.1V
C1
0.1uF
R2 150
R1 150
C2
.022uF C3 82pF C4
330pF VR1
9.1V
MK1
PTT
S1
MICROPHONE HEAD
L2
0.29uH
J2
4
2
1
L10
0.56uH
0.56uH
0.56uH
L9
L8
R
G
7
L7
C7
100pF
C8
6pF
COAX COAX
BLK BLK
GND
WHT WHT
PTT
L1
0.29uH EXT MIC
MIC
CORD
GRN GRN
LS1 BLU BLU
ACCESSORY
CONNECTOR
SIDE VIEW
RED RED
SPKR
SPKR
0.56uH
10 11 12
7 8 9
4 5 6
1 2 3
G
R
S2 1
23HI
LO
63MA81083C59-O
CAPACITOR, Fixed: pF±5%; 63V
unless stated
C1 2113741B69 0.1µF
C2 2184008H19 .022µF
C3 2113740A53 82
C4 2113740A67 330
C5, 6 Not Used
C7 2113740F51 100
C8 2100861428 6
JACK:
J1 Not Used
J2 - - - - - - - - - - Mechanical parts; items 2, 3, 5, 6,
8, 9, and 10 on exploded view
COIL, RF: unless stated
L1,2 2462575A04 Choke, 1µH
L3 thru 6 Not Used
L7 thru 10 2405452C54 Choke, 0.56µH

4
Exploded View Parts List TPLF-4196-B
ITEM MOTOROLA
NO. PART NO. DESCRIPTION
10105954T45 ASSEMBLY, Housing, Mic Head (includes
items 23,24,28, 29, and 31)
20405534U01 WASHER
34305533U01 BUSHING, Antenna
40205791P02 NUT, Toggle Seal
52900005369 LUG
63205560U01 SEAL, Rubber
7- - - - - - - - --ANTENNA, Typical
80305559U01 SCREW, Pin
90205543E03 NUT, Spanner
10 0405327S01 WASHER, Bearing
11 7582154D33 PAD, Speaker
12 1405490Q01 BOOT, Microphone
13 SEE NOTE MICROPHONE
14 8405352S01 PRINTED CIRCUIT BOARD, Main
15 0300139047 SCREW, Cutting
16 0105955P12 ASSEMBLY, Cover
17 3305706X46 LABEL, Kit Number (NMN6227B)
or3305706X47 LABEL, Kit Number (NMN6234B)
or3305706X48 LABEL, Kit Number (NMN6236B)
18 3205082E03 GASKET, O-Ring (2 req’d)
19 0382210E19 SCREW, Cover-Captive; #4-40 (2 req’d)
20 030013982 SCREW, Machine #2-56x.188" (4 req’d)
21 0105959N54 ASSEMBLY, Belt Clip
22 3205082E63 GASKET, O-Ring
23 SEE NOTE DOME, PTT (S1)
24 3205264L06 SEAL, PTT
25 8405296R02 PRINTED CIRCUIT BOARD, PTT
26 SEE NOTE SPEAKER (LS1)
27 4305407R01 SPACER, Speaker
28 3205190R05 PAD, Seal
29 7505136L03 PAD, Silicon Sponge (2 req’d)
30 SEE NOTE SWITCH, Toggle (S2)
31 4505211R02 LEVER, PTT
32 - - - - - - - - --Not Used
33 3305269R01 LABEL, Nameplate
34 8405213S01 PRINTED CIRCUIT, Flexible
35 0405465C01 WASHER, PLASTIC (2 req’d)
36 2900003025 LUG
37 - - - - - - - - --CABLE and CONNECTOR; factory test
required, not field repairable
Note:Refer to Electrical Parts List for part number and description.
34
13
12
14
37
1
4
6
2
33
9
7
8
5
24
23
3
10
11
15
16
36
17
29
19 35 18
30
29
28
26 27
20
21
25
31
22