The Black Strat. Circuit wiring – Part 3. Hooking it all up.

I’ve already soldered the pickup ground wires to the back of the volume pot. The “hot” wires from the pickups have been separated off and bundled, so that they’ll run over the back of the volume pot – within the constraints of the pickup rout. Once the route of the wire run has been established – I check my pickup identifications are clearly visible, and then bind the wires together using another short piece of shrink tubing. The ends of the wires can then be neatly routed, down by the bottom of the switch, and around the micro switch bracket. This leaves a little slack in each wire. With the route established, each of the “hot” wires are then trimmed to meet their associated terminals on the main switch.

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The three pickup connections to be made are:

  • Neck pickup to terminal S2
  • Middle pickup to terminal S3
  • Bridge pickup to terminal S4

The connections at S3 and S4 can be soldered straight away – but the S2 connection for the neck pickup is left unsoldered for now. Since the neck pickup is also controlled by the micro switch, (for the function of the Gilmour modification), I need to first establish the modification wiring – which also connects at S2. I can then solder the two wires to the terminal, together, with one blob of solder.

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The Gilmour modification is a simple addition to the standard, Stratocaster wiring schematic, which I’ve, so far, been following. The mod adds an additional wire from the neck pickup terminal of the switch, (S2), and connects it – via a small micro switch – to the volume pot input. Since the bridge pickup signal is already connected to the volume pot via the main switch – the modification allows you to additionally switch in the neck signal “in series”, whenever the bridge pickup is selected. The micro switch needs wiring up so that a short wire runs from terminal S2 to either G1 or G3. I can’t tell which way the switch functions – (ie: whether the “switch up” is on or off). I’ll wire it up to G1 first – and then check the functionality when I check the pickups.

So far, I’ve followed the standard, Stratocaster schematic, and have adopted a logical, typical colour assignment for the wiring. White wires are typically “hot” circuit wires, and black wires are “ground”. I have some different colour options to hand – so decide to put the two wires for the modification in blue, to differentiate the mod from the standard circuit. The first wire is inserted into terminal S2, alongside the neck “hot”, and the solder joint made. The wire is then laid down to the bottom of the switch, and looped around to the micro-switch at G1, where it is also soldered. I’ve left enough slack, however – just in case the switch is upside-down, and I need to switch over to G3.

The final half of the Gilmour mod is a wire run from the micro switch at G2, to the volume input terminal at V1. Once again, the wire is laid and soldered, with enough slack to lay neatly and to avoid getting in the way of anything else, should I need to do any subsequent troubleshooting. That completes the wiring on board the scratchplate. All that is required now, is to connect the circuit on the plate, to the hot and ground signal wires leading to the jack socket, and the central grounding point.

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This is where things can get a bit fiddly – and it’s where you realise that leaving enough slack in the connecting wires can be a good thing. With the scratchplate inverted, and laid onto the guitar body – as if it had been opened, like the pages of a book – I can keep the connecting wires as short as possible. It’s a good idea to cover the body with some protective padding – to avoid scratches from the knob and switch tips. It’s also not a bad idea to lay some protective surface over the rest of the exposed body too. Bits of hot solder have been known to fly off and, no matter how much you concentrate, you may not always be super-aware of just where the end of that soldering iron is. (What is that burning smell??)

The wires from the jack socket have been twisted together – again to benefit from any slight screening effect, as well as to keep things nice and tidy. The “hot”, white signal wire to / from the jack socket is connected and soldered to the volume pot at V2.

I have already soldered on a lug to the end of the black ground wire. This lug is now connected to the central gounding point – along with the two other lugged, grounding wires. (One running through from the tremolo claw, and the other from the running ground fly lead, from the back of the control pots). The single, small screw holding the three lugs is enough to make a reasonably secure, electrical connection on it’s own – and the continuity of the ground can be checked with a multimeter. However, once continuity has been demonstrated across all the ground side wires and surfaces – I like to flow a little solder across the three lugs, the screw and the copper cavity lining – just to hold things in place, and ensure the best contact possible.

With the circuit now laid and connected – the scratchplate can be inverted, laid into place, and the pickups and switches tested for functionality.

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With all of the pots turned fully up (clockwise), the guitar is connected to an amplifier, and the volume of the amp set low. The pickups can be tested by touching the poles of each with a screwdriver. A working pickup sounds a distinct “thump”. The pickups are tested so that they work only when they are selected with the appropriate selector switch, and a check can also be made as to the correct function of the guitar volume pot. You can sometimes hear a difference in tone with the tone pots too – but that isn’t always so apparent.

I also have to check the Gilmour micro switch too – and it’s here that I discover I’ve obviously wired it upside-down. I unplug the guitar from the amplifier, reverse the plate again – desolder the blue wire at G1, and resolder it again at G3. After reversing the plate again, and reconnecting the amp – I’m pleased to see that the switch now functions correctly. The neck can now be switched into the circuit whenever the bridge pickup is also selected. This now gives me the alternative of being able to add the neck signal in to the mix whenever the pickup selector switch is set to position one (bridge only), and position two, (bridge and middle). These two alternatives, in addition to the standard 5-way switch selections, give a total of seven pickup configurations, and gives the modification it’s alternative name – the “7-way” modification.

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While checking the pickup functionality – I’m also checking for any unwarranted interference or other circuit noise. There is a slight, general hum – but I suspect that to be the usual hum associated often with domestic supply and internal lighting. My testing amp, (a Vox VT40+ modelling amp), seems particularly prone to this – but with all the attempts to shield the circuit I’ve made, I must say I’m a little disheartended to hear any hum at all. My custom, hand wired Fender Blues Junior seems much more immune from interference problems, and I’m delighted to discover that when the Black Strat is connected to the FBJ – it’s virtually silent. Seems I have a noisy Vox amp – but a properly working, Black Stratocaster.

With all the checks complete – I can refit all the stainless steel screws, and fix the scratchplate into position. Careful, once again, not to overtighten anything, and split the acrylic plate. With the plate properly in place, it’s a simple task to install the switch tip and control knobs from the, specially customised, Fender Accessory kit. The Antique White knobs are modified to reflect a “greening” of the letters and numerals on the knobs over time – and as seen on Gilmour’s original. The letters would have been gold coloured on the original, and the “greening” seems to be down to the oxidisation of whatever metallic inks were used in the original manufacture. The volume knob is installed first. With the volume pot turned up full – the knob is pushed into place with the “10” on the dial, facing the adjacent bridge pickup height adjustment screw. The two tone knobs are then pushed into place in the same orientation, and so that all the words align with the pots fully turned up to 10. The switch tip completes the cosmetic job. It pushes tightly onto the switch tip, without any need for reinforcing glue.

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The guitar is now ready for stringing and setup. In the scheme of things – it’s flown together much more quickly than I’d originally anticipated. To get it properly set up, I’ll need to get to grips with adjusting the tremolo properly. Something I avoided on my previous Strat build. I’m a bit pushed for time at the moment, so I may have to shelve progress – just for now – but I’m itching to get the guitar into a proper, playable state. If it sounds as good as it looks – I’ll be well pleased.

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