THG TIM 2015, Technical Manual

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TIM 2015 Technical Manual v1 (February 2018) Page 20
5. The liquid crystal display does not illuminate.
This could be for one of six different reasons.
(1) The connectors at either ends of the connecting cable (flylead) between the PCB and the display are displaced or offset to the left or
right (yes it’s easily done). Check visually.
(2) Accidental solder splash bridging two or more pins of the plug at the display end of the cable.
(3) Wires of the flylead have been transposed (connected in the wrong order). See sketch in Chapter 4, Wiring .
(4) Loss of continuity in the flylead (probably a loose Molex connector; see first problem in this section). Check with your multimeter
using the Resistance mode or even better the Resistance–with-audio-tone made if available.
(5) The plug at the display end of the cable has been pushed onto the pin header of the display the wrong way round. See sketch in
Chapter 4, Wiring. The body of the plug lies back over (covering) the PCB; it does not project over the edge (outside) of the board.
(6) The serial connection has not been made on the underside of the PCB. Most displays have three gold-plated lands that enable the
display to operate in either parallel or serial mode. In the photo that follows these are labelled JP2, circled in red. Our display needs
to operate in serial mode, so we need to connect the central land to the land above it, marked S. Make sure the central and upper
lands are scrupulously clean, using the Garryflex pad mentioned early in this instructional. Then heat each land with a hot soldering
iron and touch it with fine solder to ‘tin’ the gold pad. Then bridge both pads with the tip of the soldering iron and add a tiny
amount of solder so that the two pads are linked. Make sure the link you make does not touch the P pad.