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                             K E N W O O D
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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 # 981
MODEL: TH-77A
SUBJECT: MEMORY LOSS WITH LOW BATTERY PACK

Some of the TH-77A handhelds in serial number range S/N 206XXXXX 
intermittently lose memory when the NiCad battery pack becomes discharged. 
The following modification will correct this condition. TH-77A transceivers 
in serial number range S/N 207XXXXX and above will incorporate a change 
in the microprocessor to prevent this condition.

This modification requires the ability to desolder a surface mounted 
micro-miniature chip resistor from a flex PC board. If you do not remove 
micro-miniature chip resistors from flex PC boards on a regular basis, 
DO NOT attempt this modification.

Be sure to remove the battery terminal plate in step 2. If the battery 
terminal plate is left on the transceiver (only the top 2 screws removed) 
the flex cable for the CTCSS unit can be damaged.

REQUIRED PART:
33K OHM CHIP RESISTOR		RK73GB1J333J

MODIFICATION PROCEDURE:

1. Disconnect the battery and antenna.

2. Remove the 4 screws from the battery terminal plate and then remove 
   the plate. FIGURE 1

3. Remove three case screws from the transceiver. FIGURE 1

4. Carefully open the transceiver. Be careful not to break the flex cable 
   that connects the front panel Control board to the body of the transceiver.

5. Locate chip resistor R301 on the Control board inside the front panel 
   of the transceiver. FIGURE 2

6. Check for a solder bridge between the foil trace connected to the bottom 
   of R301 and the foil trace below it. If present, carefully desolder the 
   solder bridge.

7. Remove chip resistor R301.

RECOMMENDED METHOD: Use a hot air jet system to melt the solder on both 
sides of the resistor. When the solder is molten, remove the chip resistor 
with a pair of tweezers.

OPTIONAL METHOD: Use a wedge shaped soldering iron tip to melt the solder 
on both sides of the resistor at one time. As the solder melts, the chip 
resistor will lift from the board and stick to the soldering tip. 
Do not attempt to pry the chip resistor from the board. FIGURE 3

8. Install a 33K ohm chip resistor in place of R301. Do not re-connect the 
   solder bridge removed in step 6.

9. Assemble the transceiver. Make sure the CTCSS board is positioned 
   correctly so the flex cable is not stressed. Do not force the radio 
   together.

Time required to perform this modification is 1 hr or less.