Park Air Systems T6T, User Documentation

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T6T VHF 100 W Transmitter Page 20 Maintenance
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Removing and Refitting the Front Panel Assembly PCB
The Front Panel assembly PCB is located as shown in Fig 14 . Removing this assembly necessitates the
removal of both Power Supply modules and partial removal of the Combiner BIT module.
Dangerous voltages are present within the transmitter. Care must be taken by personnel to
avoid accidental contact with exposed circuitry when the covers are removed and power is
applied to the radio.
Removal
Before attempting to remove the Front Panel assembly PCB, ensure that the transmitter is isolated from
the ac and dc input supplies. Then proceed as follows:
(1) Remove the transmitter top and bottom covers.
(2) Disconnect CN4 (34-way ribbon cable) at the Processor module. Carefully push the cable
through the aperture to the other side of the chassis.
(3) Refer to the instructions for removal of the Combiner BIT module, but do not remove any
connectors. The Power Supply modules must be removed and the Combiner BIT module’s
securing screws must be removed so that it can be lifted slightly away from the chassis. This
permits the ribbon cable to pass under the Combiner BIT module.
(4) Disconnect SMB connector CN5 at the PA Control module (note how the cable is routed to the
front panel).
(5) Remove the two handles from the front panel by removing the four M5 x 20 mm panhead screws.
(6) Remove the four countersunk M3 x 6 mm screws that hold the front panel to the chassis. The
front panel can now be moved away from the mainframe while guiding the ribbon and coaxial
cables from within.
(7) With the front panel free from the mainframe, release the control knob by unscrewing the Allen
head grub screw using a 1.5 mm Allen key. Withdraw the control knob from the spindle.
(8) Remove the Front Panel PCB from the Front Panel assembly by removing the six M3 x 6 mm
panhead screws and wavy washers.
Refitting
To refit the Front Panel assembly PCB, proceed as follows:
(1) Place the PCB in position on the front panel. Ensure the spindle of the control knob and
microphone/diagnostics connector are correctly located. Secure the PCB to the Front Panel
assembly using the six M3 x 6 mm panhead screws and wavy washers previously removed.
(2) At the front panel, place the control knob onto the spindle and using a 1.5 mm Allen key, secure
the Allen head grub screw.
(3) Feed the ribbon and coaxial cables through their respective holes at the front of the chassis
(4) Secure the Front Panel assembly to the top and bottom of the chassis using the four M3 x 6 mm
countersunk screws. Fit the two equipment handles using the four M5 x 20 mm panhead screws
previously removed.
(5) Route the ribbon cable under the Combiner BIT module, through the aperture to the Processor
module and connect it to CN4.
WARNING Dangerous Voltages