Saturday, October 10, 2015

Anatomy of a Mini Slide Switch

One of the most essential components involved with much of the mods that I do involve the employment of mini dpdt slide switches, which are predominantly of the two position, (on/on) six pole piece variety. For those of you that are new to this, pole pieces are the lugs that stick out from the back of the switch, which is where the wires are soldered up to make a connection... much like how you would solder up the lead and ground wires to the lugs on a potentiometer (AKA: volume and/or tone controls) on a guitar. Then again, that's probably not a good comparison, but it operates on the same basic principle.

This image up above came from this page in The GuitarWiring Blog
which explains a great deal of how mini throw switches operate.

Anyways, one thing I found out through a lot of trial and error was that most of the wiring diagrams that are widely available could be slightly misleading because what one would automatically assume to be the correct wiring for one type of switch (i.e. a slide switch) doesn't exactly hold true for the other type of switch (AKA: a mini toggle switch).  If you were using slide switches, you would eventually notice that these wiring diagrams are essentially upside down.  So that's where common sense comes into play.  What it really all relies upon is the basic structure of the switch's contacts themselves.

You see, a throw switch (or mini toggle, if you want to get technical here) operates when the base of its shaft makes contact with the ends of the lugs.  And since this contact point is at the end of the shaft, it's only natural that that point is actually on the opposite end of where the tip is pointing, like a see saw, or a fulcrum.  Try to picture if you were holding a bat, for example... the point of contact would naturally be your hand, which would be located at the base of the bat, of course, and not the tip. If you were to point the bat upwards at an angle, your hand would naturally be below it, whereas if you were to point it to the ground, your hand would be above it.  The slide switch, on the other hand, tends to hover right above the contact points, hence the reason why you usually have to swap the wiring from the top and bottom rows of lugs (or poles) in order to make them work logically; with the on function being in the up position and the off function being in the down position.  Here's a diagram which will hopefully clear up all of this technical jargon...

There is one specific instance which I can cite where this argument gets completely thrown out the window.  And that's whenever one decides to wire up a switch (regardless of whether it's a slide or a throw switch, that is) so that it can be a series/parallel toggle.  For some reason, which I honestly fail to understand, the way that the series/parallel switch is wired (see the diagram below) can easily be applied to both types of switches in the exact same way that it is illustrated.  So there's really no need to swap the bottom row of soldered wire contacts with the ones in the upper row of lugs.

Image Provided by Rothstein Guitars

Another type of switch that belongs to this family of switches is a push/pull or push/push pot.  Structurally, they are basically the same 6 pole DPDT type of switch, except that they have the extra added convenience of being attached to a potentiometer, which allows modders to easily wire up some extra controls without sacrificing some precious real estate... in other words, you don't really need to drill holes into your pickguard to accommodate some extra switches!  And when it comes to wiring up controls such as these, the only thing you have to remember is that the lugs closest to the base of the pot are essentially the row that activates the switch... much like the opposite end of the aforementioned baseball bat analogy (or the base of the mini toggle switch, if you want to be more specific) or the row of lugs on which the slide switch hovers over when it's in the on position.

So basically put, anything that's soldered onto here is what gets activated when the push/pull switch is engaged (or basically put... when the knob is pulled up).  On the other hand, if the control was a push/push pot, then you would have to press it in order to engage and disengage the switch.  Pulling up on a push/push control could unintentionally damage it, so be careful that you note the difference beforehand.  Below are two sample custom wiring images, once again from Rothstein Guitars and Seymour Duncan.  Despite the fact that one wiring is meant to turn on the neck pickup while the other is meant to turn on the bridge pickup, you're essentially activating or better put... introducing the pickup into the circuit in either wiring; where it normally wouldn't be sounding by soldering the respective wires onto their indicated places.  However, it is interesting to note that the added jumper wire that eventually gets hooked up to the hot input (or leftmost lug of the potentiometer) is located on the row of lugs nearest to the base of the pot on the push/pull switch in the Seymour Duncan diagram while in the other example, this wire is located in the middle, whilst the respective leads of the neck and/or bridge pickups each share the alternating lug.  Essentially speaking, since these types of effects are basically doing the same exact thing, it is perfectly logical to solder them either way.  Now, if you wanted the effect to work in the exact opposite direction, what you would do is take the wire that's closest to the bottom and swap it out with the lugs at the top.  So that you would have the bridge or neck pickup turn off when the switch is thrown to the up position, or the knob is activated (i.e. pulled up).

Alternatively, if you were to wire up a slide switch using this Rothstein diagram (up above), the switch would only function when it was in the down position... because as I mentioned before, the slide switch "hovers" over the metal contacts, thus turning the effect on and off in the same exact direction, whereas the mini toggle switch would work in the opposite direction, since the base of its shaft is pointing towards the lugs that would essentially activate or deactivate an effect.  Also note that if you leave a row of lugs alone without soldering anything onto them, you're essentially breaking the circuit, because no circuit can be complete without a paired wire to complete it.  So you really can't have a ground or lead wire operating by itself without it's compliment; which clearly explains why the lugs that are not soldered are essentially the off or typically the down position sides of a switch.

Now, all this talk of comparisons is getting me slightly off topic, for I wanted to focus this blog entry on specifically the slide switches that I use for my mods.  I first became acquainted with these styles of switches through GuitarFetish, as they include them in the custom pickguard wiring kits that are designed specifically for their Brighton Rock line of pickups.  Of course, I would like to point out that I don't want to sound like I'm endorsing this company and/or Seymour Duncan for that matter, especially since the lack of quality control on the former has put me off from ever ordering anything from them again... which leads me right to my discovery of an alternative, which I'll gladly share with you all.  But going back to when I first got this kit and couldn't make heads and/tails of their wiring diagram which was incorrect in some areas, I wound up burning some of these switches unintentionally (and who could blame me for trying?) for they are really small and harder to work with than the regular sized Fender style slide switches; which are bigger real estate-wise and are more comfortable to work with.  This type of slide switch, however, really takes some skill to get used to.  In fact, I can say that I really cut my teeth wiring up these types of switches.  Of course, not until I purchased an extra set of switches only to have them delivered to me without any mounting screws... prompting me to get a hold of their lame excuse for customer service and demand that the missing set of screws be sent to me... which explains my whole ongoing love/hate relationship with them all, doesn't it?

Anyways... after looking around eBay, I came across this seller from the far east (i.e. China) whose storefront is only an extension of a main business website called Uxcell.  And this website has a very similar type of switch which is a great alternative to the more expensive ones sold by the aforementioned unmentionables (whose name I will only utter if I follow it up by turning my head and spitting).  In fact, they are so cheap that you can buy them by the bulk, and still get a lot more bang for your buck than anything the US vendors can offer.  Ain't capitalism grand, dad?

There is of course, are one or two small technicalities though.  One of which, is the peak hour at which the main website is operating.  I'm guessing it must have some low bandwidth issue, which is why the pages take an infinitely long time to load.  And the other technical (or should I say physical?) setback is that the switches don't come with mounting screws.  I actually had to try my luck with StewMac to get some suitable screws for that one.  And while the mounting screws for the regular Fender style slide switches did seem to work for the three way slide switches; which are the metric type tele screws (which are short and have a mushroom style head on them rather than the conical tapered ones) sometimes they were slightly a bit too thin for the two way 6 lug slide switches, so I had to purchase the CRL and Oak-Grigsby style tele switches which are slightly thicker and a bit harder to thread into the switches themselves.  So much so in fact, that the majority of the time, the mounting screws are threaded slightly off and go into an angle.

This slight incline tends to make the screws crash into the PCB board area of the switch (i.e. underside of the shaft of the switch) and either damages it completely, or simply leaves a circular melted chunk at the edge of these boards, due to the high velocity impact of the electric drill I'm using at the time (and trust me... it's a lot harder to screw in by hand, especially when you've just made an impromptu hole in the pickguard!).  The latter of these two possible outcomes is easier to live with, though all this can easily be avoided if I just find a good hardware store that carries just the right... however, they usually don't have them, since these are technically specialty type screws, so I'm sure you easily can see my ongoing dilemma here.

Notice how you can just make out the top screw's threading
marring the edges of the small contact board.

And in this shot, you can see how these five way switch mounting
screws' threading can essentially take a small chunk out of
the housing of the contacts on the slide switch due to the angle
being slightly off due to the mounting hole being slightly smaller.

The other thing I've noticed about the difference in between the two; aside from the metal housing on one and the black housing on the other is that the shaft of the switch for the aforementioned turn your head and spit company is slightly longer than these highly suitable and less expensive counterparts from China.  There's a seller that offers both of these variations on eBay. The same is true for the replacement slide switches that they offer for the bigger Fender style Jazzmaster type of switches.  Aside from the usual established company name branding and all,  I always wonder who makes these decisions when it comes to designing something that's just that much slightly off and enough to distinguish it from the original.  I'm sure it has a lot to do with avoiding a potential patent lawsuit, don't you?

Notice the difference in the length of the switch shaft
between these two switches which are exactly
the same but sold by different vendors.
Additionally, the holes for the mounting
screws vary in size as well.

Anyways... below are some links (that'll probably take forever to load) for certain mini slide switches.  I wasn't exactly able to find the 6 lug type that I usually use for my mods from Uxcell, but as I mentioned above, they can be bought from user friendstore1682010 (though I can't really vouch for it, since I'm not quite sure if it's the exact same size as the ones I have).  Another eBay seller you should check out to get these switches is hongkongsuperseller.

3 lug on/off mini slide switch with black chasis

3 lug on/off mini slide switch with metal chasis

6 lug on/off/on mini slide switch with black chasis

The last link above is for a three position slide switch (yes, I was just as surprised to when I found out that there were actually making three way mini slide switches now).  What you'll immediately notice with your naked eye is that there is a grill on the side of these switches which contains a small ball bearing which is needed to essentially lock the switch in the center position to prevent it from easily sliding to the up and down positions only.  So it's basically a divider mechanism to toggle between the selected lugs.  Other than that extra piece of hardware, the components are nearly the same for each type of switch (i.e. on/on vs. on/off/on).  The on/off/on switch has no springs for the metal strip contacts that slide or hover over the lugs' contact points, instead it just has one spring for the aforementioned ball bearing; which makes sense, since this is what is necessary to provide for the right amount of friction for the switch to function in the housing itself.  The on/on switch, on the other hand, has two small springs for each contact strip (which are longer).  Refer to the images below to get the bigger picture (no pun intended, unless you click on the thumbnail links that is!).

Components of an on/off/on mini-switch. Note the one spring for the ball bearing
which is housed in a hole on the side of the switch itself.  The other thing to note is
that the metal strips are smaller and wrap around the lug contacts whereas the
ones on a mini on/on switch (see picture below) appear to be much flatter.

And here are the innards of a mini on/on slide switch.  This one has wider strip
contacts and a pair of smaller springs (one of which I lost when I took this photo!)
that are housed in a pair of trench-like channels directly beneath the tip of the switch.

There is another variety of a three way on/off/on switch that is available in the standard Fender Switchcraft size can be found on StewMac, however it's designed for Mustangs or Duo Sonics and has eight lugs instead of the six found on the aforementioned three way mini switches.  The only difference when it comes to wiring up the two; (say in a coil splitting set up, for example) is that you have to wire the center lug of the three way switch twice for the Switchcraft, so the two rows in the center would essentially be soldered together.  Here's a few images which can illustrate that fact a bit better...

This image above, which can be found on the StewMac product page
for the Switchcraft style slide switches explains how the two variations
(i.e. on/off/on and the on/on slide switches) work when they are wired up.

And here is a side by side comparison so that you can
see the difference in scale between the two switches
which each have the same function, but with
an extra lug on the bigger switch only.

And here is a wiring diagram provided by GuitarElectronics for
wiring up a four conductor humbucker pikup into a coil selecting setup.
What's really odd about this diagram is that even though it specifies that
the wiring is intended an SPDT on/off/on mini toggle switch, the layout is
essentially what a modder would be using for a slide switch, because the lead wire
is at the top and not at the bottom; as it should be on a regular mini toggle switch.
So this is a perfect example of a slightly misleading diagram that I mentioned earlier.

So there you have, my fellow mod heads--- I know there's still a lot more to cover, but we've all got to start somewhere. I keep wondering when parts manufacturers will successfully produce an on/on/on slide switch; but I think that would be a feat in engineering, in and of itself. Definitely a lot to ask for. So in the meantime, stay tuned (no pun intended) for our next installment...

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