Motorola Two Way Portable Radio Ht750 Ht1250 Mtx850 Mtx1250 Mtx8250 Mtx9250 Basic 68p80906z54 D Manual

							Maintenance3-11
Figure 3-8: Lock Retainer Catches to the Radio’s Body
3.7.5 Chassis Assembly Reassembly
1. Slide on the ground contact (if it was removed) on the top corner boss of the chassis. 
2. Replace the O-ring. The tabs on the O-ring should reach into the chassis and point down.
3. Stretch the O-ring to place it into the retaining pocket at the bottom end of the chassis.
4. Ensure that the antenna nut insulator is correctly replaced by pushing it all the way to the top of 
the antenna nut.
5. Replace the battery contact seal (if necessary) surrounding the battery contact. 
6. Place the main circuit board straight down on top of the chassis.
7. Use the T6 TORX screwdriver to fasten the screws holding the main board to the chassis.
3.7.6 Chassis and Front Cover Reassembly
1. Align the chassis assembly end-to-end with the front cover assembly.
2. Insert the tails of the flex circuits into their respective connectors at the bottom of the front cover.
3. Push down the latches on the connectors to hold the flex circuits to the main board.
4. Slide the volume potentiometer and frequency switch shafts into their respective holes in the front 
cover.
5. Push the chassis assembly completely into the top of the front cover until it settles in place.
6. Be sure the O-ring is properly seated.
7. Snap the bottom of the chassis into the front cover.NOTE: When properly assembled, the retainers on the O-ring should align with the slots on 
the chassis. If this is not the case, remove and replace the O-ring until it is aligned 
with the chassis and completely seated in place around the perimeter.
NOTE: Be sure the battery contact seal protrudes through the chassis and is not pinched 
under the chassis.
Catches
Retainer 
						

							3-12Maintenance
8. Reassemble the knobs, dust cover, antenna, and battery.
Figure 3-9: Fastening the Chassis 
3.7.7 DTMF Retrofit Kit Procedure (Optional Upgrade Procedure)
If you are performing an upgrade from a basic model to a DTMF model, replace the existing front 
cover kit with kit number HLN9984 and follow the reassembly steps to reassemble the upgraded 
radio. (See paragraph 3.7 for details about reassembly.) 
To activate the retrofit using the radio software, follow these steps:
1. Start the Customer Programming Software (CPS).
2. Read the codeplug data by clicking on the READ icon in the menu bar, or by selecting READ 
DEVICE in the pulldown menu.
3. Open the Radio Configuration dialog box. (See Figure 3-10.)
4. Change the Keypad Configuration from “No Keypad” to “Programmable/Numeric”. 
(See Figure 3-10.)
5. Write the codeplug back to the radio by clicking on the WRITE icon in the menu bar, or by 
selecting WRITE DEVICE in the pulldown menu.Figure 3-10: Activating the Retrofit
Radio
Chassis 
						

							Maintenance3-13
3.7.8 Option Board Installation
1. With the keypad retainer removed the keypad backer board can be removed without the use of 
tools.
2. Remove the jumper flex from the connector on the keypad board. Notice the orientation of the flex 
to the connector. Arrows on the jumper flex point to the correct way of inserting the flex into the 
connector.
3. Discard the keypad backer board.
4. The “breakaway” tab at the top of all option boards contains an extra row of keys and is used to 
accommodate other radio models.
5. Break-off and discard the option board tab, taking care not to damage the option board. Trim any 
tab fragments that may remain on the option board.
Figure 3-11: Changing Keypad/PassPort Board /Option Boards
6. Reassemble the option board to the front cover assembly.
7. Insert the display flex circuit into the connector on the option board.
8. Insert the jumper flex circuit into the connector on the option board. Notice the orientation of the 
flex circuit. Arrows on the jumper flex point to the correct way of inserting the flex into the 
connector.
9. Replace the retainer by placing the two top hooks into the slots below the speaker in the front 
cover; then, pivot the retainer into the front cover. Ensure that all four tab arms snap correctly into 
the front cover.
10. With the keypad option board, display, and retainer correctly in place, the front cover assembly 
can now be reassembled per paragraph 3.7.6. NOTE: The CPS may display a warning dialog box when you attempt to write the codeplug 
back to the radio. It is safe to ignore this warning. Press the OK button.
TO KP
RetainerJumper
Flex
Keypad/
Option
Board
Display
Flex 
						

							3-14Maintenance
Notes
. 
						

							3-29
3.8.15 HT1550•XLS Exploded ViewFigure 3-19: HT1550•XLS Exploded View
1
2
3
4
5
6
7
8
910
11
121314
15
1617
18
19
20
21
22
2324
2526
2728
29
30
3132
33
3435
3637
384041
42
43
44 39 
						

							3-303.8.16 HT1550•XLS Exploded View Parts List
Table 3-8.  HT1550•XLS Parts List
Item
Motorola Part 
Number
Description
1 See Section 7 in 
manualAntenna
2 3280529Z01 Knob, Volume
3 3280530Z01 Knob, Frequency
4 1380525Z03 Escutcheon, Top (Dotted)
5 3380644Z01 Escutcheon, Adhesive
6 3280533Z01 Seal, Control Top
7 6180527Z01 Litepipe, Tx
8 HKLN4011A Nameplate, HT1550•XLS
9 1586059A01 Dust Cover, Univ Conn
10 1386058A01 Escutcheon, Univ Flex
11 1580666Z02 Front Cover DTMF
12 Not Field 
ReplaceableEscutcheon, FM
13 7580532Z01 Keypad, Side Control
14 1380528Z01 Bezel, Side Control
15 7585745Z03 Keypad
16 0104008J38 Keypad Board Assembly
17 5105385Y57 LCD Module
18 7585659Z01 Pad, Retainer Front
19 4285660Z01 Retainer, Keypad Board
20 7585659Z02 Pad, Retainer Back
21 3586057A01 Felt, Speaker
22 3586170A01 Felt, Mic
23 1405368W01 Boot, Mic
24 5085738Z03 Speaker
25 5005227J08 Microphone
26 8480549Z01 Flex, Univ Conn
27 2113740A41 Cap, 33pF
28 4280504Z01 Retainer, Speaker
29 1480503Z01 Boot, Backup Battery
30 6062884K01 Backup Battery
31 0304726J04 Screw
32 3980667Z01 Contact, Finger (For UHF)
33 Typical Ctrl/RF Board Assembly
34 8485615Z01 Flex, Keypad/Controller
35 1480652Z01 Insulator, Antenna
36 7580556Z01 Pad, Thermal
37 3280534Z01 Seal, Contact
38 3380564Z01 Label, Warning
39 3280536Z02 Gasket, O-Ring
40 3980698Z01 Contact, Ground (For VHF)
41 2780518Z02 Chassis
42 1586178A01 Shroud, Chassis
43 See Section 7 in 
manualBattery
44 HLN9714 Beltclip
Table 3-8.  HT1550•XLS Parts List (Continued)
Item
Motorola Part 
Number
Description 
						

							Service Aids3-35
3.9 Service Aids
Table 3-11 lists service aids recommended for working on the HT750/HT1250/HT1250•LS/
HT1250•LS+/HT1550•XLS/MTX850/MTX950/MTX850•LS/MTX8250/MTX9250/MTX8250•LS radios.
Table 3-11:Service Aids NOTE: While all of these items are available from Motorola, most are standard shop 
equipment items, and any equivalent item capable of the same performance may be 
substituted for the item listed.
Motorola 
Part No.Description Application
RLN4460Portable Test SetEnables connection to audio/accessory jack. Allows 
switching for radio testing.
HVN9025 Customer Programming Soft-
ware (CPS Plus) CD ROM. 
Includes PPCPS (PassPort Cus-
tomer Programming Software, 
Global tuner, Reflashing tool, 
tutorial, frequency finder and fre-
quency table).Programs customer option and channel data. Tunes 
hardware parameters, front end, power, deviation, 
etc. Conventional, LTR, and PassPort products.
HVN9067Customer Programming Soft-
ware (CPS).Same as above (Privacy Plus protocol products).
AARKN4075 Programming Cable Includes radio interface box (RIB) capability.
AARKN4074Programming Cable/Test CableConnects radio to RIB (RLN4008B).
AARKN4073 Radio to Radio Cloning Cable Allows
 radio to be duplicated from a master radio by 
transferring programmed data from the master radio 
to the other.
RLN4008Radio Interface BoxEnables communications between radio and com-
puter’s serial communications adapter.
HHLN4134 BNC Adaptor Adapts radio antenna port to BNC cabling of equip-
ment (VHF and UHF, B1 only).
5880313B69SMA to BNC adapterAdapts radio antenna port to BNC cabling of equip-
ment (800 MHz radios).
RLN4510 Battery Eliminator 7.5V Regula-
torWorks in combination with Shop Battery Block, 
0180305G54.
AA0180305G54
AA8180384F68Shop Battery Block
Bench Test Housing EliminatorInterconnects radio to power supply. Provides for 
troubleshooting of radio when housing is removed.
0180357A57Wall-Mounted Power Supply 
(120 VAC)Used to supply power to RIB.
0180358A56Wall-Mounted Power Supply 
(220 VAC; 2-prong)Used to supply power to RIB.
3080369B72 Computer Interface Cable Connects computer’s serial communications adapter 
to RIB (RLN4008B). 
						

							3-36Test Equipment
3.10 Test Equipment
Table 3-12 lists test equipment required to service the HT750/HT1250/HT1250•LS/HT1250•LS+/
HT1550•XLS/MTX850/MTX950/MTX850•LS/MTX8250/MTX9250/MTX8250•LS radios.
Table 3-12:Recommended Test Equipment
Motorola Part 
No.Description Characteristics Application
R2000, R2600
R2400, or R2001 
with trunking 
optionService MonitorThis monitor will 
substitute for items 
listed below with an 
asterisk *Frequency/deviation meter and sig-
nal generator for wide-range trouble-
shooting and alignment
*R1049 Digital Multimeter Two meters recommended for AC/
DC voltage and current measure-
ments
*S1100Audio Oscillator67 to 200Hz tonesUsed with service monitor for injec-
tion of PL tones
*S1053, 
* S K N 6 0 0 9 ,              
*SKN6001AC Voltmeter, 
Power Cable 
for meter, 
Test leads for meter• 1 mV to 300 V
• 10 MΩ input imped-
anceAudio voltage measurements
 R1053Dual-trace Oscillo-
scope20 MHz bandwidth,
 5 mV/cm - 20 V/cmWaveform measurements
*S1350,
*ST1215 (VHF)
*ST1223 (UHF)
*T1013Wattmeter,
Plug-in Elements 
(VHF & UHF), RF
Dummy Load• 50 Ω 
• ±5% accuracy 
10 W, max. 0-1000 
MHz, 300 WTransmitter power output measure-
ments
 S1339RF Millivolt Meter100 µV to 3 VRF, 10 
kHz to 1.2 GHzRF level measurements
*R1013 SINAD Meter Receiver sensitivity measurements
 S1347 or
 S1348 (prog)DC Power Supply0-20 Vdc, 0-5 AmpsBench supply for 7.5Vdc 
						

							Configuring and Wiring the Programming/Test Cable 3-37
3.11 Configuring and Wiring the Programming/Test Cable
Figure 3-22: Programming/Test Cable AARKN4074
Figure 3-23: Pin Configuration of the Cable Side Connector
Block 
						

							3-38 Configuring and Wiring the Programming/Test Cable
Figure 3-24:  Programming/Test Cable Schematic
1
2
5
7
8
9
16
18
19
20
21
22
25 15AUDIO -
AUDIO +
MIC AUDIO
GND
VOL CTRL
DISC
PTT
OPT SEL INT/EXT
BOOT CTRL
1
4
15
25 11GND
BIAS
BUS +
BOOT CTRL BUS -   1
  2
  3
  4
  5
  6
  8
  9
10
11
12
13   7 EXT SPKR +
  EXT SPKR -
 OPTION B+
 EXT MIC
OPT SEL 2
  OPT SEL 1
 RX DATA
TX DATA
RSSI
XMIT/RX AUDIO
BOOT CTRL
N/C  GND
P2
TO RADIO
TEST SET
RLN4460 P1
TO RADIO
UNIVERSAL
CONNECTOR
J1
TO RIB
RLN4008
FL0830062O
10K