2 - PCB Assembly

[Tony]

The 3x 4n7 coil tuning capacitors are next, they're pale grey rectangles packed in a paper strip of 3:

[Tony]

The 2x precision 1n capacitors that feed the LV supply. These will be either pale grey or geryish pink (NOT brown or beige) and packed in a strip of 2 in paper or plastic:

[Tony]

Time to start on the top side of the board, with the LEDs. These have a corner cut out of them to mark pin1, the 5 on the top of the PCB thse face to the bottom right:





The last 2 on the underside face top right:

[Tony]

Some more 3-legged beasties, the BAV99 diode packs. There's 3 of these in a black antistatic plastic strip:

[Tony]

The BSS123 cathode drivers next. There's 10 of these in a black antistatic plastic strip:

[Tony]

Not many small components left now, fit the 100n capacitors next. There's 10 of these in a paper strip:

[Tony]

A slightly trickier one - the 4x 2.2u caeramics that provide smoothing for the 3.9V supply. The picture looks like there's 2 but it's a pair of 2x stacks so all 4 are connected in parallel. They're on a strip of clear plastic, 5 beige rectangles:

[Tony]

The last small component is the 3.9V zener diode which limits the supply voltage to the LEDs and PIC. It's in a single black plastic strip section, make sure the band is facing right as in the picture:

[Tony]

Nearly ready to power up for the first time, just the decoder IC - it's the 16 pin one numbered '4028'. The pin 1 dot points to the top of the PCB:





Now go and make the rceiver coil, it'll be needed for the next step.

[Tony]

Solder 2 wire offcuts to either side of the 3v9 zener, these will be used to attach meter probes for the first test.



Solder the coil wires to these pads on the top left of the underside:



Connect a multimeter on a low volts range to the 2 wire offcuts, then move the pcb/coil assembly slowly over the top of the base coil, about 2 inches above it. Watch the meter reading to make sure it doesn't rise above 4.5V - it should reach around 3.9-4.2V and stabilise. 1-2 of the LEDs may light up randomly as well.