2 - PCB Assembly


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Post Fri Dec 01, 2017 6:46 pm

Re: 2 - PCB Assembly

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

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Post Fri Dec 01, 2017 6:49 pm

Re: 2 - PCB Assembly

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:

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Post Fri Dec 01, 2017 9:27 pm

Re: 2 - PCB Assembly

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:

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The last 2 on the underside face top right:

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Post Fri Dec 01, 2017 9:46 pm

Re: 2 - PCB Assembly

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

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Post Fri Dec 01, 2017 9:47 pm

Re: 2 - PCB Assembly

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

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Post Fri Dec 01, 2017 11:29 pm

Re: 2 - PCB Assembly

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

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Post Fri Dec 01, 2017 11:34 pm

Re: 2 - PCB Assembly

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:

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Post Sat Dec 02, 2017 1:33 am

Re: 2 - PCB Assembly

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:

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Post Sat Dec 02, 2017 1:36 am

Re: 2 - PCB Assembly

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:

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

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Joined: Tue Jul 24, 2012 8:05 pm

Post Sat Dec 02, 2017 1:38 am

Re: 2 - PCB Assembly

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

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

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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.
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