70s Japanese short scale guitar wiring

[oldraven]

I saw a similar post here with another guitar that looked like it might have come from the same Japanese factory in the 70s. The only differences are this guitar has a 3 position rotary switch and two single coil pickups. The owner's kids were playing with it and just spun the rotary switch until the wires were a mangled mess. I ended up getting a new 2 pole 3 position switch to keep the original switch on there. But these pickups have 3 wires coming off of them. I'm thinking one might just be a common ground for the pickup's metal case to work as a shield. I've completely shielded the CAVERNOUS body cavity and am ready to put it back together. I'm fairly new to all of this. I rebuilt my 94 Jazz a couple of years ago, and did a refurbish and shielding job on my brother's two guitars. With great results each time. But I'm a bit baffled by wiring the rotary switch in. I didn't have to make any changes to the selector/pickup wiring on the Strats. Any help would be appreciated.

[oldraven]

[newey]

Jul 8, 2022 18:44:23 GMT -5 oldraven said:

I'm thinking one might just be a common ground for the pickup's metal case to work as a shield

That's probably a good guess. But you should test things with a multimeter to be sure. If you don't have one, they can be had at most hardware stores for under $20, you don't need a fancy one. This will also allow you to test that the vintage pickups are still operational, and also to test that your rotary switch, even though it's brand new, isn't a defective one. I've wired up a guitar with a new switch that was bad, and it took me forever to figure out that the issue wasn't my soldering job but a faulty switch.

Also, if we could get a look at the other side of the pickguard, as well as the headstock, etc., the guitar could prehaps be difinitively ID'd. This might lead to a factory OEM wiring diagram which would allow you to ensure it was rewired to original. Some vintage Japanese guitars from this era had their pickups wired in series instead of parallel, and it would be important to know that if vintage correctness is a consideration.

If that isn't a consideration and you just want to wire the pickups in parallel such that the rotary gives both pickups in the center position, with the bridge pickup alone at one end of the rotation and the neck alone at the other, then you would wire the rotary switch as follows:

First, we'll assume that the blue wires from the two pickups, which appear to be wired together, are in fact the shield wires, which would then be wired to ground. But as I said above, you should test this first to be sure. If this is true, then the red and black wires from each pickup are the signal connections. You would wire the black wires to your ground point.

on the rotary switch, there are two solder lugs set towards the inside of the switch. These are the common lugs. Each common lug then has 3 corresponding lugs around the perimeter of the switch, across from each common lug. So, this diagram shows how to wire it. Note that the numbering is completely arbitrary- which way the knob goes to select the neck pickup versus the bridge pcikup will depend upon how you orient the switch when you install it in the guita, as it is rotationally symmetrical.



EDIT: And, oldraven, I'm forgetting my manners:

Hello and Welcome to G-Nutz2!

[oldraven]

Dude, you are a friggin superstar! That is how I want to wire it for him. Bridge/both/neck. There is a patent number on the truss rod cover. 34-4127 It says Kawai on the headstock. A word I've seen way too many times on the internet, but never saw it on a guitar. The only other markings on it is the word Japan on the neck bolt plate. It's actually a pretty rad looking little unit. These photos still had the old switch.

Thanks for the welcome!

[oldraven]

The pots came from a preloaded switchplate cover I bought for my Jazz. I got all new Fender pots for that job, so I had these as spares. It turns out they were actually 500k pots, and not the 250k ones I needed. I'll see if this ends up giving the guitar a decent tone. If it's way off, I still have the original 10k and 50k pots. It might be insanely hot. I should probably just order some new ones of this size and the stock impedance.

[newey]

Don't tell me I'm a superstar. But, please do tell that to my wife . . .

OK, several things. First, Kawai was a major manufacturer in Japan back when, they made guitars under many different nameplates including their own. Second, your shielding job looks good, but shielding the cavity under the trem, at the tailpiece there, is superfluous. There's no electronics in there so it can't be a source for any noise. You should probably check that the shielding does connect, via contact, to the jack sleeve.

Third, looking at the big blobs of solder on that rotary switch, I'm guessing that wasn't how Kawai did it- someone has been in there at some point. And, only one pole of the rotary appears to have been used, which would seem to indicate that the two pickups were combined in series, not parallel. But it's hard to tell from the pictures.

If you have the original pots, test them with a meter (I still want you to test the switch, too). I doubt that they are truly 10K and 50K, those values won't work for passive pickups. 500K pots are fine, if they're too bright, turn the tone down a notch.

[ashcatlt]

It is way too early and I can’t see all the used lugs so I can quite make sense of that “original” wiring, if there are actually only two wires to other things, it almost has to be a series wiring of some sort.

That knob looks to me like it’ll give a person plenty of torque to screw up that switch pretty good. One might say it’s a good thing the whole thing spun because it’s pretty easy to crank cheaper switches like this far enough that they never work again. I also think that’s just an unfortunate spot for a switch that’s so easy to accidentally flip. My baritone has a tele style switch in approximately that position, and when I really get rocking, I still sometimes accidentally flip the thing. That situation is of course much worse since it’s not a pickup selector but a kill switch.

[Yogi B]

Jul 9, 2022 17:54:04 GMT -5 newey said:

looking at the big blobs of solder on that rotary switch, I'm guessing that wasn't how Kawai did it- someone has been in there at some point.

I'm not so sure, I think all the pickup leads might have originally gone to the switch. Looking at the top of one of the photo's it looks like you can see what the remaining blue wires are connected to — I see one connected to lug three of presumably the old volume pot (along with a yellow wire, which I assume goes to the tone pot); the other switch wire (and notably the one with the biggest solder blob) looks to go to the pot's casing i.e. ground.

Additionally in the original photo, seeing the 'fresh' extension to the blue (presumably shield) wires (I'm guessing this is of oldraven's doing, or at least not original), I'm prompted to look at the lengths of the other wires. Okay, they may have been trimmed if the mechanical stress that disconnected them from the switch also broke the wire along its length, but until I'm told otherwise I'm going to assume that isn't the case. Relatedly, if you (oldraven) haven't done so already, I'd put a meter across the coil's wires to measure the DC resistance and check they are still intact — I also wouldn't be too surprised if they're pretty low impedance (as that would be a possible explanation of the low pot values).

Also, as I touched on it here, if the blue pickup leads are indeed shield wires you should be able to measure continuity between them and the pickup's base plate, in addition to not having continuity from the blue lead to either of the red lead or the black lead.

But back to the wire length, based on what I can see of the 'neck' pickup's blue wire I don't think either it or either of the other two leads would reach the pots (presumably also the reason for the aforementioned extension), assuming the wires haven't been shortened this would also support the 'all wires went to the switch' theory. Furthermore, noting the emphasis I used on the word "neck", do you have any pictures from before you disassembled the guitar? In the post shielding picture it appears that the leads of the bridge pickup are shorter than those of the neck. For most guitars this thinking is 'correct' — however, under my theory with the wires going 'forwards' to the switch, it'd be reversed. Could you have accidentally swapped the pickup's when removing them during the process of adding the shielding?

Jul 9, 2022 17:54:04 GMT -5 newey said:

And, only one pole of the rotary appears to have been used, which would seem to indicate that the two pickups were combined in series, not parallel. But it's hard to tell from the pictures.

I think it's two poles (the original switch being a 3P3T with one unused pole). But — as one pole has a connection to hot, the other to ground, and there's a wire between them — it does still look like series wiring is likely. Though, as you say, it is pretty tough to tell exactly what is going on from the photo's. Different angles would help, on the other hand an accurate diagram derived from what can be seen (and tested) in person would also be excellent.

Something I don't think any reasonable level of forensics could uncover is if the two pickups were originally combined in (or out-of-) phase, (as with the other points) comparisons to other guitars of the same model would really help — alas, so far I've had no luck finding even an external shot, let alone one of the wiring. However there is another potential source of information: the owner. Assuming the damage was recent and the owner was familiar with the guitar before the damage occurred: can they describe the tone of the three switch positions? Was one position particularly loud or particularly squawky/nasal? (Knowing if one of the pickups is reverse magnetic polarity of the other could help too, as you wouldn't go to that trouble to then wire them out-of-phase and thus not hum-cancelling. However I suspect they're both the same polarity, which would be inconclusive.)

Jul 10, 2022 9:52:35 GMT -5 ashcatlt said:

That knob looks to me like it’ll give a person plenty of torque to screw up that switch pretty good. One might say it’s a good thing the whole thing spun because it’s pretty easy to crank cheaper switches like this far enough that they never work again.

Or for the old and probably therefore quite brittle plastic switch lever to crack/split/snap (and not for the first time, by the looks of it).

[Yogi B]

Jul 12, 2022 0:14:08 GMT -5 Yogi B said:

comparisons to other guitars of the same model would really help — alas, so far I've had no luck finding even an external shot, let alone one of the wiring.

Update: I've since seen a 3-pickup and a 1-pickup hardtail version both rebranded under the Conqueror name, but still no joy for a 2-pickup version of the same model.

However, I did find an ebay listing for a control plate assembly from a hollow-body Kingston (another name under which Japanese imports were sold) and I'm pretty sure it has a functionally identical switching arrangement. It also has 50k volume & 100k tone pots (re-reading the prior post I now see you said 10k & 50k, and agree with newey that 10k is especially low — perhaps you missed a zero?).

Thankfully it is much more cleanly wired and thus I can more easily see what's going on (I did have the suspicion that the larger solder blobs on yours spanned multiple terminals, having now seen it done deliberately I'm now pretty certain that's the case). Here's a diagram of what I think see with the Kingston's switch:

Note: bridge & neck labels could be swapped — I'm working under the assumption that pushing the lever forwards/clockwise selects the neck pickup and backwards/counter-clockwise for the bridge.

Also this does have the 'both' position as series, and though we can't be sure about phase I'd duplicate the fact that the series link formed between the pickups consists of the bridge's black wire & the neck's red wire — hoping that the wire colours are maintained across the two guitars.

[ashcatlt]

Huh. If I’m reading that right, it would leave the bridge hanging upside down from hot in position 3, which may have some impact on noise performance. Other guitars like this that I’ve seen usually short the unused coil in both single positions, and that would be the way I’d probably wire it unless it’s really just trying to be like factory accurate restoration.

[Deleted]

I'm reading the switch as

1) +B to Output, -B to Ground so B
2) +B to Output, -B to +N to Ground so BxN
3) +N to Output, -N to Ground so N

Got to say made me smile the way they did this as we focus on the "Hot" end so much.
You can turn off ever end before or after as long as the flow can not travel it's ok. As for floating !! I don't like this term, the current in my light switch is "Floating"

Guess in theory that position 3 could be

N+(BxResistance to Ground)
Resistance being the air between the connection points

----
Hook -B and +N together
+B always to Output, and -N always to Ground
B0 -B&+N, B1 GND, B2 N/C, B3 Out

Will that make people more happy, so when it's just Neck, Bridges both ends are hooked to Output.