The Ash Stratocaster – Pickup upgrades, wiring and circuit installation.

With the new pickguard installed – I can see that there’s not a great deal of clearance at the bridge. Even the slightest bit of binding here might result in the guitar not returning to tune, once the tremolo bar is operated. The clearance seems less at the treble side – so that might result in the bridge plate twisting slightly. It’s not ideal. The tremolo plate needs to be held securely, and yet be completely free to pivot.

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The easiest way to remove a little bit of material from the edge of the scratchplate, is to scrape it away with a sharp Stanley Knife type blade held perpendicular to the edge of the plate. Sanding it results in a raggy, rounded-over, edge – wheras scraping it allows you to feather in the adjustment, and keep the edge square. And it’s especially useful to be able to blend into the rounded 90 degree corners, without enlarging the radii. It helps to mark a guide line on the removeable plastic film, so you can keep an eye on how much you plan to take off. That way – you can pare away at the edge of the plate, check the fit, and ensure the edge of the cutaway is visually straight. It took me a bit of backwards and forwards to get it right – but I ended up removing just over a millimetre of the plate at the treble side. I took the clearance at the sides of the bridge as a guide – and aimed to replicate that, all the way around. Once the plate has been shaped – there’s usually a little burr left on the edge of the face, and that can be gently pared away with a sharp blade, held at a slight angle. The end result now looks to give plenty of clearance.

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The wiring scheme will be mostly based around the standard Stratocaster wiring schematic. I first like to wire the jack socket, and join it to the central grounding point. That means I can screw the jack socket home once and for all, and do everything else in the main cavity.

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I’ve gradually refined the way I do my standard Stratocaster jack wiring. There’s not a lot of room in the cut-out, and if the wires are installed straight onto the lugs – the solder joints can get pushed back against the sides of the cut-out. Since they’re copper lined, and a part of the ground side of the circuit – this can lead to intermittent shorts when a jack plug is inserted or removed. I’ve changed the procedure to allow the wires to be soldered kind of sideways-on, with the hot wire looping up and over the centre line. Both wires are soldered so they’re heading directly towards the small conduit hole which will carry the wires into the main chamber. This keeps both wires free from kinks, and unecessary bends. A little bit of shrink-wrap over each solder joint helps to maintain the insulation – and where the two wires come together, I twist them around each other to keep things tidy, and to take advantage of any slight benefit intertwining wires may offer, to the overall shielding of the signal.

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Now the jack socket can be attached to the socket plate, with the wires now heading in the correct general direction. The twisted wires are pushed through into the main cavity, and the jack plate screwed down into place. Once the jack plate is properly installed, the wires can be pulled taught in the main control cavity. The twisted wires continue a path across the opening, and then they diverge again. The a tail of white, “hot” wire is left to connect to the volume pot later on. The tail of black, “ground” wire has a small tab soldered to the end, and that joins the tabbed ground from the tremolo claw at the central grounding point, and both are held in place with a small screw, to the side of the copper lined cavity.

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A new CRL, 5-way switch is attached to the scratchplate using the stainless steel screws from an upgrade screw set, and three, CTS, 250k pots are bolted into place using the nuts and washers provided. I always like to add a dab of thread lock – just to stop things from coming adrift. I don’t intend to remove these often, and wandering pots can always put stress on solder joints, over time. Once the electrical components are in place I go ahead and solder together the basic wiring, based on the standard, Stratocaster schematic. I prefer to use cloth covered wire, and to colour code the runs, so that ground side wires are black – the rest white.

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With the switch and pot wiring complete – all thats needed is the tone capacitor. Once again, I’m using a reproduction, but “period correct”, 0.05mf Luxe, “Orange Dime”  capacitor. It’s worthwhile taking time to cut and bend the capacitor legs so that the disc sits nicely over the tone pot, and to use a little bit of insulating tube to stop the disc shorting out onto the back of the tone pot.

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Then it’s time to install the pickups. I had to order in some pan-headed pickup attachment screws, since everything seems to come supplied with countersunk options. Each screw is fitted with approximately 1cm of rubber tubing, to act as a spring. I much prefer the tubing over the alternative metal spring option. All of the existing pickup covers are replaced with off-white, “Vintage 60’s” style covers from a Fender, Pure Vintage accessories set.

The two Fender Custom Shop ’69 pickups are the first in. The ’69 pickups are quite interchangeable – and I’ve already used the old middle pickup for another build. One pickup measures a DC resistance of 5.33k, and the other 5.74k. I figure the middle pickup should be slightly more powerful than the neck pickup – and so that’s helped sort out which pickup to use where. The eventual relative loudness of the pickups will be “matched” later, when the pickup heights are adjusted in setup.

As usual, I twist the pickup wires together, and I find it helps to keep things tidy by putting a bit of shrink wrap around the bundles wires just below the middle pickup. This keeps the runs straight and true, down through the centrally connecting pickup rout.

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Next to be installed, is the Seymour Duncan, Custom Shop SSL-5 pickup, in the bridge position. I’ve been warned that the pickup leads need to be reversed, since Seymour Duncan pickups are wound in the opposite direction to Fender pickups. It is sometimes the preferred option to install this pickup also with the magnetic poles reversed, (RW/RP), so that the pickup effectively hum-cancels in the 2 and 4 positions – but I’m using a standard configuration pickup here. With all the shielding I’ve put in – I’m hoping I won’t need hum-cancelling. Just reversing the hot and ground wires should keep the signal in phase with the two Fender pickups, but I don’t think the ’69’s were ever designed to incorporate hum-cancelling. I may be wrong – let’s see what we get.

The wires from the SSL-5 are soldered into position. The white, “ground” wire joins the two black “ground” wires from the ’69’s and all three are routed along behind the bridge pickup, and soldered to the back of the volume pot. The black “hot” wire from the SSL-5 is bundled together with the two white “hot” wires from the ’69’s and all three are looped around the assembly, with a little extra shrink tubing to help keep them together. The ends are then soldered to the correct switch lugs. A short length of black wire is soldered to the back of the volume pot, and a lug attached to the other end. This forms a fly-lead which will connect the wiring circuit to the central, grounding point on the body.

I’ve heard, and read, a fair bit about a “bridge tone” modification, and I’m planning to try it out to see how it affects this particular pickup combination. Normally, the Stratocaster wiring schematic allows for a general volume control, and separate tone controls for both neck and middle pickups. The SSL-5 pickup is considerably “hotter” than the specification of the pickup it replaces, and I think it might be useful to be able to control the tone of the bridge pickup a little – just to fine tune some of the sharpness I anticipate. The “bridge tone modification” involves running a jumper wire joining the bridge pickup to the middle pickup’s tone pot – so that they can be controlled together. As usual, I like to colour code any deviation from the standard wiring configuration, and so run the jumper wire in red, cloth covered wire. I’ll see how it suits the pickup configuration, and if I find it better to stick with the standard – I’ll remove it later.

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With the plate now all wired up, all it takes is to screw the three, lugged ground wires to the central grounding point. (Once the circuit is tested and functional, I like to add a dab of solder over the three tabs, the screw and the copper grounding foil – just to make the join solid, and a bit more secure).

The white “hot” wire from the jack is then soldered to the middle lug on the volume pot – and that’s it. The plate can be eased into position for testing. With an amp attached, a screwdriver confirms that each pickup is functional, and that the switch and pots are correctly configured. The plate can now be finally screwed down, and the rest of the plastic hardware installed. The pickups have already used the covers from the Fender Pure Vintage 60’s set, and now the switch tip, pots and whammy bar get their matching bits and pieces. I peel the protective film from the scratchplate and give it a bit of a clean – just to get rid of any fingermarks. I like the slightly yellowed covers against the black guard, and prefer this look over the previous “all black” look. I’m looking forward to getting to hear how it sounds.

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I’m now in the enviable position where I have two Strats waiting for the tremolos to be floated. Both waiting for a first time setup. This upgrade for my Ash Strat, and also the Black Strat replica. Looks like this could be a busy, but rewarding week – with a lot of things coming together.

UPDATE:
So this is me thinking I’ve learned and memorised the basic Stratocaster schematic. What do I know? I’m kind of embarrased to admit I’ve developed some kind of wiring dyslexia, and completely miswired the tone pots on this build. Testing the pickups didn’t reveal the problem – everything operated as it should with the basic screwdriver test. Then, I was looking at the circuit, doing a final check over and it just clicked that I’d got everything out of line somehow.

Basically, the wires from the selector switch to the two tone pots were reversed, and then the wire from the switch to the volume pot was connected to the wrong terminal. I sort of memorised the schematic successfully. I had the all the right wires – just in all the wrong places. Fortunately there was no high voltage load on anything, (although I’m going to have to get sharper with this if I’m ever going to build my own valve amp). Note to self: check with a schematic, or you risk looking like a prat. But then making mistakes is the only sure fire way to learn.

Fixing the idiot wiring was simple enough. Tone wires reversed, and the volume wire relocated. Print out a schematic from the web – look at it, and look at the wiring again. Look hard at the wiring again, and then check the schematic. One more time…

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