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                             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   <<<
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                        Kenwood Service Centers

   Kenwood Service Corporation             Kenwood Service Center, East
   2201 East Dominguez Street              829 Lynnhaven Parkway, Suite 130
   Long Beach, California 90801            Virginia Beach, Virginia 23452
   Telephone 1-310-639-5300                Telephone 1-804-340-1702

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BULLETIN # 972
MODEL: TM-631A/TM-731A
SUBJECT: MEMORY LOSS MODIFICATION


Some TM-631A/731A owners have reported that the transceiver intermittently 
loses its memory channel information at power on. The following modification 
will correct this condition.

Read all instructions before proceeding. Do not attempt this modification 
if it is beyond you capability.

REQUIRED PARTS:	ZKIT-731MEMO

The kit contains:

NJM78L06A		6V AVR
1SS133  		DIODE
MTZ3.0JB		3.0V ZENER DIODE
CE04NW0J221M	        220uF, 6.3V ELECTROLYTIC CAPACITOR
C91-0457-05	        0.022uF CERAMIC CAPACITOR
CK45B1H103K	        0.01Uf CERAMIC CAPACITOR
RD14BB2C103J	        10K OHM, 1/6W RESISTOR
RD14BB2C102J	        1K OHM, 1/6W RESISTOR
RD14BB2C472J	        4.7K OHM, 1/6W RESISTOR
RK73FB2A472J	        4.7K OHM, 1/10W CHIP RESISTOR (QTY. 2)


1. Disconnect the power supply, antenna, and microphone.

2. Remove the top and bottom covers (12 screws). Do not damage the 
   speaker wires when removing the top cover.

3. Pull the Main Encoder, Volume, and Main Squelch knobs off the front 
   panel. If a knob does not easily pull off, wrap a cloth around the 
   knob and carefully pull it off with a pair of pliers. Be careful not 
   to crush or scar the knob.

4. Remove the two brass colored screws from the top of the plastic 
   front panel. Figure 1

5. Gently lift the two tabs on the bottom of the front panel and then 
   pull the front panel off the transceiver. Figure 2

6. Remove the two black shades from the Balance and Sub-Squelch controls. 
   (Figure 3)

7. Remove the three brass colored screws from Control board B/3. Figure 3

8. Remove the brass colored screw that is mounted on the front panel 
   chassis above the Power switch. Figure 4

9. Remove the brass colored screw that is mounted on the front panel 
   chassis to the right of the microphone jack. Figure 4

10. Carefully pull the front panel assembly away from the body of the 
    transceiver

11. Disconnect the two "wire type" cables from the body of the transceiver.

12. Disconnect the two flex cables from the front panel assembly. The 
    flex cables simply pull out of the connectors.

Refer to Figure 6 for the next 4 steps.

13. Remove IC102 and R103.

14. Cut the foil pattern between connector CN101 and chip capacitor C102.

15. Add the components shown in Figure 6.

16. Change R105 from a 47K ohm chip resistor to a 4.7K ohm chip resistor.

17. Straighten the tabs that hold the LCD assembly to the Control board. 
    Figure 5. Carefully pull the LCD assembly off the Control board 
    (do not break the flex cable).

18. Remove C123. Figure 7

19. Add the components shown in Figure 7.

20. Replace C107 with the 220uF electrolytic. C107 is located between 
    the Main and Sub rotary encoders. Figure 3

21. Mount the LCD assembly on the Control board and bend the four tabs 
    to hold it in place.

22. Connect the two flex cables to the front panel assembly and then 
    plug the two "wire type" connectors into the body of the transceiver.

23. Mount the front panel assembly on the body of the transceiver and 
    secure it with the three brass colored screws that go through the 
    Control board. Be careful not to pinch any wires.

24. Install the brass colored screw that goes above the power switch and 
    install the brass colored screw that goes to the right of the 
    microphone jack.

25. Install the two black shades on the Balance and Sub-Squelch controls.

26. Slide the Lock, Balance, and Sub-Squelch controls to the left.

27. Slide the Lock, Balance, and Sub-Squelch knobs on the plastic front 
    panel to the left.

28. Gently install the plastic front panel on the front panel assembly. 
    Do not force the installation.

29. Install the two brass colored screws on the top of the plastic 
    front panel.

30. Remove the shield from the UHF Final compartment on the bottom of the 
    transceiver.

31. Remove the two screws from the small board where the positive power 
    lead connects.

32. Solder the remaining 4.7K ohm chip resistor to the foil side of the 
    board as shown in Figure 8.

33. Assemble the Final compartment and install the covers on the transceiver.

Time required to perform this modification is 1 hour.