TS440 Protecting Q33

If pin 7 (RL) of the remote connector is accidently connected to ground, current from the 14 volt line (14L) will damage transistor Q33
on the IF unit. This will prevent the radio from transmitting. To protect Q33, a 4.7 ohm resistor should be installed in series with the
RL line on the foil side of the IF board. In the event that pin 7 is connected to ground, the resistor will open, but the transceiver will
still be capable of transmitting.
Required part:
4.7 Ohm, 1/6 Watt resistor …….. RD14CB2C4R7J
1. Disconnect the power supply and antenna from the transceiver.
2. Using a #2 Phillips screw driver, remove the 9 screws from the top cover of the transceiver. Remove the cover and unplug the
speaker wire.
3. Locate connector 19 on the IF unit.
4. Using a #1 Phillips screw driver, remove the 7 screws that secure the IF unit to the chassis of the transceiver.
5. Pull the board up and rotate it towards the front of the transceiver to expose the foil side of the board.
6. On the foil side of the board, locate the trace that is connected to pin 3 (brown wire) of connector 19.
7. Using a craft knife, cut the trace comming from pin three so as to open the foil trace.
8. Solder the 4.7 ohm resistor across the now open trace (i.e. in series with the trace).
9. Assemble the transceiver by reversing steps 1 - 5.
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This is an optional change that may not be covered under warranty.
Time required for this modification is 0.5 hrs or less.
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GW1NGL NA7KR Kevin Roberts Ham Radio

Page last updated on 09/10/2012 by Kevin Roberts NA7KR a colection of Ham Radio and Electronic Information