Modifications for the Kenwood TM-742

Microprocessor Change, TM642/742/942


K E N W O O D
A M A T E U R - R A D I O - S E R V I C E - B U L L E T I N

BULLETIN # 1042
MODEL: TM-642A/TM-742A/TM-942A
SUBJECT: Microprocessor Change

This bulletin supercedes ASB-1033.

Symptom:

Reports of problems with microprocessor lock-up when using S-meter squelch, problems with storage/recall of PL tone frequencies of 203.5 Hz. and/or 114.8 Hz., or problems with a lack of transmit on the UHF band modules during Remote operation can be corrected using the changes noted in this bulletin.

Notes:
  1. All TM-642A transceivers work fine and do not require any changes.
  2. TM-742/942's that exhibit any of these symptoms with serial numbers between 412XXXX and 509XXXX need only change IC1 on X53-3460-21 B/2.
  3. TM-742/942's that exhibit any of these symptoms with serial numbers of 412XXXX and below must also change IC1 on X54-3130-11.
  4. TM-742's with serial numbers of 509XXXX and greater have had these changes incorporated in production.
  5. Some TM-742's and TM-942's below serial number 509XXXX were returned to Japan for modification. If the unit that you have has a black dot on the box near the serial number it has already been modified and requires no further action
Parts Required:
Qty    Description    Old Part No.     New Part No.       Circuit Description

1      Microprocessor HD6433388A07F    HD6433388A22F      IC-1
                           or
                      HD6433388A14F                         

1      Microprocessor HD404719A26H     HD404719A32H       IC-1
Caution:
This modification requires advanced surface mount soldering equipment that is rated for CMOS circuits. It also requires familiarity with advanced surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself.
Attemping to remove and replace either IC without the proper equipment and techniques can easiy damage the circuit boards and void your warranty.
Seek qualified assistance from your closest Kenwood Service Center (Long Beach, CA, or Virginia Beach, VA).

Time required for this moditication is 90 minutes or less.
Microprocessor Change, TM742/942


K E N W O O D
A M A T E U R - R A D I O - S E R V I C E - B U L L E T I N

BULLETIN # 1042
MODEL: TM-642A/TM-742A/TM-942A
SUBJECT: Microprocessor Change

This bulletin supercedes ASB-1033.

Symptom:

Reports of problems with microprocessor lock-up when using S-meter squelch, problems with storage/recall of PL tone frequencies of 203.5 Hz. and/or 114.8 Hz., or problems with a lack of transmit on the UHF band modules during Remote operation can be corrected using the changes noted in this bulletin.

Notes:
  1. All TM-642A transceivers work fine and do not require any changes.
  2. TM-742/942's that exhibit any of these symptoms with serial numbers between 412XXXX and 509XXXX need only change IC1 on X53-3460-21 B/2.
  3. TM-742/942's that exhibit any of these symptoms with serial numbers of 412XXXX and below must also change IC1 on X54-3130-11.
  4. TM-742's with serial numbers of 509XXXX and greater have had these changes incorporated in production.
  5. Some TM-742's and TM-942's below serial number 509XXXX were returned to Japan for modification. If the unit that you have has a black dot on the box near the serial number it has already been modified and requires no further action
Parts Required:
Qty    Description    Old Part No.     New Part No.       Circuit Description

1      Microprocessor HD6433388A07F    HD6433388A22F      IC-1
                           or
                      HD6433388A14F                         

1      Microprocessor HD404719A26H     HD404719A32H       IC-1
Caution:
This modification requires advanced surface mount soldering equipment that is rated for CMOS circuits. It also requires familiarity with advanced surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself.
Attemping to remove and replace either IC without the proper equipment and techniques can easiy damage the circuit boards and void your warranty.
Seek qualified assistance from your closest Kenwood Service Center (Long Beach, CA, or Virginia Beach, VA).

Time required for this moditication is 90 minutes or less
28 MHz/50 MHz RC TX Failure


K E N W O O D
A M A T E U R - R A D I O - S E R V I C E - B U L L E T I N

BULLETIN # 1029
MODEL: TM-742A/TM-942A
SUBJECT: 28 MHz/50 MHz RC TX Failure

Symptom:
The 28 MHz and 50 MHz modules do not transmit after direct frequency entry from the microphone when the radio is switched to the RC function.

Corrective Action:

Replace IC1 on the Control Unit X53-3460 B/2 and IC1 on the Display Unit X54-3130 A/3.

Parts Required:
Qty     Description     Kenwood Part No.                Circuit Description

1       Control Unit microprocessor     HD6433388A07F           IC1
1       Display Unit microprocessor     HD404719A32H            IC1

Caution:
This modification requires soldering equipment rated for CMOS type circuits. It also requires familiarity with surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself. Seek qualified assistance.

Time required for this modification is 1.5 hours or less.
Modification of TM-742 & 942


Open the lower panel of TM-742.

****** There are TWO version. Please check which version your rig is.******


                      FRONT PANEL IS UPER SIDE

      ___                               ___    ___    ___     <<=== BAND SEL
   ---|-|-------------------------------|-|----|-|----|-|--------
  |                                                              |
  |______________*_______________________________*_______________|
  |     11                    2222                               |
  |    111                   22   22                             |
  |     11                      22                               |
  |     11                    22                                 |       
  |     11                   22222222                            |
  |                                                              |       
  |                                                              |       
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  1. ****** FOR OLD VERSION ******
    SEE THE POINT OF [ 2 ] .If you can find a small board masked with black sponge , your TM-742 is OLD VERSION.
  2. On right side small board , there are three lines. Make short circuit with midlle line and lower line.
  1. ****** FOR NEW VERSION ******
    SEE THE POINT OF [ 2 ] . If you can not find a small board , your rig is NEW VERSION.
  2. SEE THE POINT OF [ 1 ]. There is a chip [ 2R7 ] . And below this chip [ 2R7 ] , there are small chip [ 473 ] .
         [ GRAPHIC IS FOR JA VERSION ]
     *-*-*-*-*-*-*-*
             R R R X        R =  chip [ 473 ]
     * * * * * * * *
     * * * * * * * *        Make short circuit two X point.
             X     R        Maybe on your TM-742,there are chip [ 473 ]
     *-*-*-*-*-*-*-*        with different patern. This graphic is for
                            JA version.  So please try until modification
                            will succeed.
    
OPERATION
  1. ON 144MHz press band sel more than 1sec . mode change AM <-> FM.
  2. ON 430MHz ditto band change 430 <-> 870
  3. ON 1200MHz ditto 1200 <-> 870
  4. [F] + BELL -> repeater dual RCV.
  5. 118-136MHz mode chang to am automaticaly.
  6. X-band repeater operation. Select one band by [BAND SEL] select onother band by [CONT SEL]. Press [F] key more than 1sec. Press [MUTE] Key. X-band operation will work. Press [F] then [MUTE] key -> cancel X-band repeater operation.
73s DE JP1LRT @ JL1YVX.10.JNET1.JPN.AS
YOSHIHARU "KEI" TSUKUURA
Extended frequency for TM-742E


Before open your TM-742E, be sure you have disconnect the power. Don't do this modifications if you hare not sure or if you have not the necessary knowledge in eletronics to do this !

Open the lower panel (see your User Manual for details)

You will have something who looks like that :
      _                      _    _    _
     I I                    I I  I I  I I     <== Vol. & Squelch Boutton
  ------------------------------------------
  I   Here  I                              I
  I_________I   Control Unit               I
  I             X53-346X-XX A/2            I
  ------------------------------------------
You can find a range of CMS chip resistors who looks like that :
      0      1
_______________________________
     # #    #-#  Bit 0
     #-#    # #  Bit 1              # #  mean no CMS Chip resistor
     # #    #-#  Bit 2              #-#  mean CMS Chip resistor
     #-#    # #  Bit 3
     #-#    # #  Bit 4
     # #    #-#  Fan Delay Bit 0
     # #    #-#  Fan Delay Bit 1
     # #    # #  Repeater Bit



   With bit 0 set to 1
        bit 1 set to 0
        bit 2 set to 1
        bit 3 set to 0
        bit 4 set to 0 
You have the extended frequency on VHF from 118 to 174 MHz
You have the extended frequency on UHF from 410 to 470 MHz
You have the extended frequency on UHF from 800 to 1000MHz

On 144MHz, if you press MHZ Key more than 1 second, mode change AM<=>FM
On 430MHz, if you press MHZ Key more than 1 second, band change 430<=>870

Note that from 118 to 136MHz, the mode change automaticaly from FM to AM and you can see a "A" which replace the One hundred MHz (ex : A18.125MHz)

You have the repeater possibility (for more detail, see page 59 of your Kenwood Instruction Manual)

In fact, your TM-742E now as mostly the same functions that the TM-742A which is for the US market.
Fan Delay time setting


The fan can be controlled by setting the chip resistor (R66 & R65, 47kHom) for fan delay bits 1 and 0 as follows :

-----------------------------------------------------------------------
    FAN CONTROL               | Fan Delay bit 1  |  Fan Delay bit 0   |
-----------------------------------------------------------------------
On when power is On           |       0          |          0         |
-----------------------------------------------------------------------
On during transmission        |       0          |          1         |
-----------------------------------------------------------------------
On during transmission and    |                  |                    |
for 1 minute after trans. end |       1          |          0         | 
-----------------------------------------------------------------------
On during transmission and    |                  |                    |
for 2 minuntes after trans end|       1          |          1         |
-----------------------------------------------------------------------

Wireless remote control with DTMF handheld transceiver


When you use the MC-45DME microphone, you can of course have the remote function which is explain in the Instruction Manual on page 61 "Remote Control by DTMF Microphone".
When you put the TM-742E in Remote Control mode by pressing more than 1 second the "F" key then the "RC" key, you can control some of the function with a Handheld DTMF like the TH-28E or TH-22...
It is not writen in the Kenwood Instruction Manual how to use it. So I had some difficulty to find some of the possible remote functions.

CHANGE YOUR TM-742E TO A TM-942E (which don't exist on the market)


If you want to put the 1200MHz band unit, you simply reffer to your Kenwood Instruction Manual and you have a display who looks like that :
       ________________________________
       | 1296.000 | 144.550 | 432.800 |
       --------------------------------
       |=   0   ######## . 0   0   0  |
       --------------------------------
This is not really convenient as the logique would be to have the 1200MHz display at the far right of the Transceiver.

So if you want to have something who looks like the TM-942A but with a TM-742E + 1200MHz band unit, just change the 144 and 430MHz band unit lower (reffer to the Kenwood Instruction Manual page 94 and after, just like if you install an optional unit), then you will have this :
        --------------------------------
        | 144.550 | 432.800 | 1296.000 |
        --------------------------------
        |=   0   ######## . 0   0   0  |
        --------------------------------
You can also change in anyway all of the band unit to have the 430MHz on the left, 144MHz on the right...etc... just imagine what you want to have.
TM-742/942 Beyond Mars/CAP Mod. Guide


Procedure:
  1. Detach the front panel from the main chassis.
  2. Remove the bottom cover of the transceiver by removing the 4 screws on the bottom of the cover and loosening the 4 screws on the side of the unit.
  3. Orient the radio so the bottom is up and the front panel area is near your chest. Near the front panel area you will find a large board, this is the control unit.
  4. Remove the chip resistors "Y" noted in the diagram below, and reinstall them in position "Z" as shown.
  5. Reinstall the bottom cover of the transceiver and reattach the front panel.
  6. Reset the microprocessor. Press and hold the MR key while the power is switched on. Then release the MR key. This will erase all operator programmed data.
  7. The frequency range after modification will be:
            28  Mhz Band:   RX:   18.0 thru  54.0 Mhz
                            TX:   26.0 thru  45.0 Mhz
            50  Mhz Band:   RX:   40.0 thru  90.0 Mhz
                            TX:   46.0 thru  76.0 Mhz
            144 Mhz Band:   TX:  136.0 thru 174.0 Mhz
            220 Mhz Band:   RX:  215.0 thru 260.0 Mhz
                            TX:  215.0 thru 235.0 Mhz
            440 Mhz Band:   TX:  410.0 thru 470.0 Mhz
            1.2 Ghz Band    RX/TX: 1100.0 thru 1400.0 Mhz
    
    Please note that these are theoretical ranges only. Not all radios will be capable of tuning the entire range.
              Control Unit X53-346X-XX A/2
          _____________________________________   
                                              I
                                              I   Remove Y resistors and 
                             ---- ----        I   reinstall in position Z
                                Z IIYY        I
                             ---- ----        I
                             oooo oooo        I
                             ---- ----        I
                             IIIY   ZZ        I
                             ---- ----        I
                                            2 I
                                            R I
                                            7 I
    


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