10 April 2013

DIY: Moding the Epiphone Wilshire Ltd - Electronics and pickups

Introduction

Note: this entry was already published in my old Spanish version of this blog, around December/2010. I am just revisiting it here.
This is a good example of mod over an Asian built guitar, to enhance its electronics.
The Epiphone Wilshire Ltd is a guitar with an acceptable wood, good resonance and sustain but, as usually happens to Asian guitars, the weak spot are frets, nut and electronics.

Frets are very tinny so, extreme bendings are being affected and, since their low profile, they will last very few, since you can do very few refreting tasks there.

Electronics components are low quality ones, small pots with metric measurements, etc.
Usually, the soldering job is of bad quality but, not the case in this axe, that had a neat wiring.
In next picture, you can see the removed pickguard. Notice that just the are below pots was shielded but, even that this extends the ground to every electronics component there (except for pickups selector), since the "tap" isn't totally covered, we aren't effectively closing the Faraday's cage created by the electronics cavity. Remember that such a Faraday's cage is there to catch unwanted environmental noises throwing them to ground and avoiding those noises to be caught by electronics components.


Epiphone guitars were mounting bad sounding pickups for a long time but, this guitar mounts some humbuckers designed in USA that, honestly, sound quite nice. Very classic sound, they cut the mix very well, are clear and defined. They have a very low output level, anyway.
When I bought this guitar, I did it thinking on to swap stock pickups later. I was looking for some sound closer to Santana's one for this axe, taking into account that this guitars is some kind of SG but, with more mass so, together with the guitar I've ordered a set of Barekuckle's Abraxas.

Honestly, stock pickups are good enough and there is no need to swap them if you wanted a classic tone.
But I recommend to swap pots with some quality ones (as CTS) and the jack (Swiftcraft).


Rewiring the guitar

First step was to remove strings.
If strings are in good condition and, we have the idea to re-use them, the trick is to leave strings very lose, in a way that we can remove the stop tail piece from their posts, leaving strings and stop tail over the desk, away from our working area.
I we don't want to re-use them and, to mount new brand  strings later, the quickest is to cut them.

You should remove stop tail and bridge, because they aren't fixed to the body but, just the strings pressure maintains both on their posts.
We follow removing the pickguard. We should unscrew every screw to remove the pickguard, that will remain linked to the guitar for a few wires (usually, jack hot and ground, pickups wires and bridge ground).

We need then to remove pickups. You should remove pickups' mounting rings. First, totally lose the screws that regulate pickup height, until they fall into the cavity. Later, we can unscrew mounting rings.

We will identify the wires of each pickup and, we will cut the farest extreme (leaving the most of cable length as possible), if we aren't to re-use those electronics components or, you should de-solder those wires if you wanted to re-use those components.

Now that the pickguard is separated from the body, we can remove old pickups and to mount the new ones.

I made a mistake with this guitar. I rely the cavity was already coated with conductive paint (graphite) but, my first try after wiring everything demonstrated the opposite. Be sure to use a multimeter first to determine if there is continuity on the walls. Put your multimeter to read Ohms (a beep is enough) and check if there is continuity between to distant spots of the cavity walls.

If the cavity isn't shielded, is the right moment to spray it with some conductive paint (graphite or copper) or, to recover it with some metallic foils with conductive autoadhesive glue.

In the following picture, we can see the removed pickguard, pickups already removed and, the new Bridge pickup already in place.


To pass pickup conductors across the narrow tunnels of cavity, my trick is to wrap some isolant tape around all wires, shaping the end as a spike, what helps a lot to this task, as you can see in the following picture (both Abraxas already mounted).


As the cavity should be already shielded (not in this case), we need to coat the pickguard with some shielding foils to make this "tap" to effectively close the Faraday`s cage.
In following picture, you can see the back side of the pickguard coated with autoadhesive conductive glue copper foils. Unfortunately, I run out of stock of wide copper foils so, I had to work a lot more with the available narrow foils. With wide foils you will finish the work really fast.


See that the holes for components were covered during the process but, this is not an issue. With a cutter or the head of an screwdriver you can open the big ones. For the smaller (screw holes), it's enough to punch them with a small star-head screwdriver to open the gap.

Next step is to mount components on the pickguard.
Since we are going to change measures from metric to inches, we will need to widen the diameter of pot's holes.
The classy way should be to use a cutting tool able to provide a perfect circle in a quick and fast way (a Dremel, driller or whatever).
The cheesy way is to use some round file to widen that hole.
Since I have not a proper tool, I went the cheesy way.


To ensure the continuity of ground between the cavity walls and the pickguard "tap", you could solder a jumper wire between both. Or you can put some metallic foils inside that overflow a bit on the surface, to be sure that walls and tap are in contact.
In the cavity, over those foils, you can use a screw as the common grounding spot (where to connect bridge ground, shielding ground and any other free ground wire).



Next step is to mount components on the pickguard. After mounting all them, we check the pickguard in place (without screwing it), just to check that they fit in the cavity without issues as they are now.

In this guitar, I've substituted the typical Gibson-like 3-way selector with a 6-way Freeway selector.
If we put that selector in the stock hole, we will see that the pickguard doesn't fits the cavity.
I've had to slightly shift that hole (widening it with a file), until I made the pickguard to fit the cavity.

As potentiometers lay very close, I had to straighten their lugs, to avoid they to enter in contact, because I've mounted each pair (volume and tone) one facing the other, to make the wiring easier.


It's of a great help to have a clear wiring diagram to start our soldering tasks, without going lost.
In this picture, the design I've prepared for this particular axe.


While we wire everything, it's a good idea to highlight with a fluorescent marker, those wires and soldering spots that we have already done.
You should visually check every soldered spot (they should look clean and shinny) and, be sure that no strand is free.
You should also mechanically check the soldered spot. Move the wire circularly and check that it cannot enter in contact with any other lug or component if you bend the wire.
Try to route your wires in a way that they doesn't avoid to easily mount your finished pickguard.


Protect the legs of condensors and any other naked wire (as pickups ground bare wire), with heatshrink tubes or isolant tape, to be sure that they don't accidentally touch an unwanted part of the circuit.

Once we have all components wired on the pickguard, it's time to link the pickguard to the guitar, soldering ickup wires and guitar ground wires. In that way, we could easily work in the pickguard until is strictly necessary to establish the link.

Next picture corresponds to the finished wiring.


Tie wires together, with plastic ties, isolant tape or whatever of use, to avoid they to mess you when mounting the pickguard over the cavity. Note: even that you can cut the length of pickup conductors, I personally prefer to leave them with full length, in prevision that some day can be transferred to a different guitar.

The only pending task is to mount the pickguard, then.


You have now the opportunity to clean your guitar. Clean everything and to nurture that fingerboard if necessary.
We mount the new knobs (inches) that correspond to the new pots (inches). We mount the bridge, stop tail and strings and... time to test the guitar.

8 comments:

  1. Thanks for sharing this in English! I really appreciate all the work you put into sharing your blog and experiences. Thanks!

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  2. Thanks a lot for your attention and follow up!

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  3. I was searching for some information related to electronic wiring and came across to your post. It was really worth reading the post.

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  4. Thanks for the post, just change the pu's and soon i have a killer guitar.

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  5. I have the same model. Did you have a humming issue before you rewired all and shielded it in the right way?

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    Replies
    1. Not really. It's working flawless. No humming or feedback issues.

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  6. do you have a pdf of your wiring diagram that you can post here?

    ReplyDelete

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