*** Solved *** Wiring Question - Push-Pull Switched Pots For Splitting Coils

BillDL

Assuming all the pots including the switched tone pots in the wiring diagram below are all 500K, and when the tone knobs are pulled out the respective humbuckers are split to single coils.

If I wanted to add 470K resistors so that when the coils are split they only see 250K pots, is it possible to do this with the push-pull switches on the tone controls?  I feel sure I've done this before but if I have I can't remember how I wired it.

I know that if the push-pull pots were on the volume controls I could solder the resistors between the active lugs (middle) of the switch on the pot to the live lug of the volume pot itself like this:

Is it possible to use a resistor on a push-pull TONE POT, and if so where would I solder it?

ICBM

It’s exactly the same - the switch is physically on the tone control but it’s electrically independent. Connect the resistor between the middle switch terminal (right-hand side in the Irongear drawing) and the middle pot terminal, where the yellow wire from the volume control is connected.

The only other change you need is to snip the green and white wires between the two switch terminals, so the resistor isn’t connected to the coil junction.

BillDL

Thank you @ICBM.   I was thinking about this before I fell asleep this morning and visualising the layout.  I slapped my forehead virtually and went "Duh!" to myself when I mentally traced the wire from the volume pot input to the middle lug of the tone pot, realising it's connected directly to the red live wire from the pickup.  I still find it hard to mentally separate the independent switched sections from the pots they are a part of and I confuse myself.

I hope you're braced for my next question about Schaller pickup wiring colour oddities 

[EDIT - other "Schaller" question here: https://www.thefretboard.co.uk/discussion/296793/solved-wiring-question-schaller-pickups ]

ICBM

BillDL said:

I hope you're braced for my next question about Schaller pickup wiring colour oddities 

Now that’s taking me back. Pre-warning… I can’t remember!

What I do know is that there are 24 possible combinations of the colours in a four-conductor cable - and someone, somewhere at some time has probably used all of them .

BillDL

I'm rewiring one of my "Master Series" Fender Flame guitars from the mid 80s when their Japanese guitars used Schaller hardware.  I just need to confirm the colours of the wires and how they are used are the same in my beaten up one with original wiring as this one before I ask, or I could again look daft.  I don't mind looking daft occasionally, but twice within a couple of days might attract attention   

ICBM

If you can’t find any information, just use a multimeter to determine which pairs of wires are each coil. Temporarily connect them in series and to an amp - if it hums loudly when you hold the pickup near the amp’s transformer, reverse one coil. The combination that hums less is correct. The overall polarity - either of the individual coils or the whole pickup - doesn’t matter if you’re putting two in the same guitar.

BillDL

Thank you for that ICBM.

Dave_Mc

@ICBM 's right as usual- you just need to use the second half of the switch to do it (and disconnect the "doubled-up" way the original coil split is wired to use both sides of the switch as insurance, as he said).

You might not need the 470k resistors if you're doing partial splits, though- I've never got as far as using 470k resistors for the coil splits (they're great for single coils) because almost all of my guitars which have splits have a master split for both pickups, but I didn't bother on a couple of HSS guitars I have, because the partial splits darkened the sound enough that I felt I didn't need them.

If you're not doing partial splits with a resistor, though, I could see the 470k resistors being very helpful.

BillDL

Thanks @Dave_Mc.   Yeah, that's part of what was confusing me a bit the more I thought about it, i.e. soldering the wires to both sides of the switch in case one joint goes bad is something I've always done as a matter of course.  I couldn't visualise where to solder the resistor while "seeing" the switch wired like that.

I had wondered about a partial split but I don't actually have any suitable rated resistors at the moment.  I might get some, but in the meantime the question here about changing the impedance when the pickup is split is just in case I need it.

This question relates to my other thread about rewiring my Fender Flame Standard that has Schaller pickups:

https://www.thefretboard.co.uk/discussion/296793/solved-wiring-question-schaller-pickups

It would have originally been 1meg pots with no coil split, but somebody had changed the pots on it to 250K with coil split switches on the tone pots and no partial splitting or impedance balancing resistors.  I'm really not sure how these Schaller pickups will sound when split using the original 1meg pots if I don't add resistors to make them see 500K, because I've never seen or played the Elite or Ultra models of this guitar that came with coil splits and I don't know if they also had 1Meg pots.

I don't actually have any 1Meg pots with push-pull switches anyway, so I may just fit 1Meg volume pots and push-pull switch 500K tone pots and see how that goes.  I'm not clever enough with electronics calculations to work out what impedance the pickups would see if I used these different values though.

Dave_Mc

If you were going to buy some resistors one errand, maybe trim pots might be worth a try? Slightly fiddlier, but it does let you dial the partial split in perfectly. Very dependent on the guitar and pickups, but for me 10k for the bridge pickup and 5k for the neck seem to work best- 5k gives you a lot more fine control over the exact value, but occasionally 5k isn't high enough for the bridge pickup.

Of course it's probably a lot handier just to try the loading resistors since you already have them to hand, they may well do enough on their own!

I haven't tried that guitar or those pickups but unless the stock pickups are very dark I would guess splits would sound very bright with 1Meg pots! They usually sound bright enough with 500k if you're not doing partial splits...

I had a quick look but I couldn't find a service manual for those guitars (maybe because they're MIJ?). I found what seemed to be more like a user manual, but it didn't give the pot values (you've probably already found that one, lol).

I'm not sure I've tried it but I think @ICBM isn't fond of using a lower value tone pot than volume- it sounds like the tone isn't fully turned up I think. At very least, I don't think it would give an accurate representation of how the guitar would sound with 1Meg pots all round, it would be a bit darker.

BillDL

Bookmark this page Dave_Mc:

https://emea-support.fender.com/hc/en-gb/articles/48766814929819-Fender-Guitar-Service-Manuals

Those are the PDF documents with the full parts lists and the wiring diagrams.

You're right though, the MIJ Flame doesn't appear on the list of service manuals despite the user manuals for the three models of guitars in the 1984 Master Series being available:

https://www.fmicassets.com/Damroot/Original/10001/leg_gtr_Flame,_Japan_(1984).pdf

As far as the Fender Flame and Esprit models the only real difference was the body shape.  They both had the Standard with no coil split functionality, but the control cavity of this base model has a routed out flat ready for drilling to install a toggle switch behind the knobs.  The Elite model had the coil split toggle switch, TBX tone circuitry and fancier decoration and appointments.  The Ultra model had even fancier hardware but nothing different with the circuitry from the Elite.  I found the official service manual with parts list and wiring diagram for the Flame and Esprit Standard ages ago.  I wish I had also looked for the service manual for the Flame and Esprit Elite model with the wiring diagram at the time, but with them having the additional TBX circuitry it would have been different.

The parts list and wiring diagram (the one I coloured in for my other thread) for the Flame and Esprit Standard shows 1Meg volume and tone pots and 0.022uF MIR capacitors (silver mica or something?).

HERE is a video of Chris Buck playing the Fender Flame Elite model that's the same as mine but for the micro-adjust tailpiece, snowflake fretboard inlays, coil split, and most crucially the active TBX circuitry, so ot's not really a true representation of how mine would have sounded originally.  There are other videos of the Flame Standard on YouTube, but they are either playing jazz shit or are going through distortion.

Dave_Mc

Yeah those service manuals are great! Just a pity you kind of have to scroll through all of them to see if the one you want is available, lol.

I'm not sure what an MIR capacitor is, I tried googling it and got nowhere!

ICBM

Dave_Mc said:

I'm not sure what an MIR capacitor is, I tried googling it and got nowhere!

One that sounds the same as all the others .

Mylar in resin, probably - they’re normally just called Mylar, although they are in resin. Pretty much all guitar caps in the 80s were either Mylar or ceramic so it’s the most likely.

BillDL

Aaaah, Thanks @ICBM. ; Google's AI suggested Mica, but I knew instinctively it was wrong.  It's not like I lost any sleep over it, but at one time I did do a quick search for images of all the different types of capacitors and I didn't find any that looked the same.  "Mylar In Resin" never occurred to me.  For tone controls I normally just use the green unbranded or brown Suntan (always smile at the name) mylar capacitors because they're small and neat.  The ones used in the assembly of this guitar are something like this in appearance, where you can see the reflectivity of the film through the green tinted resin that's a bit less vibrant than the example and obviously has different writing (223K 1H Y = 0.022uF, 50v, 10%), but they have more squared off edges:

Perhaps I should hang onto these because I'm sure they have some mythical "1980s MIJ Fujigen Gakki" tone enhancing qualities and might now be very sought after 

Anyway, after much experimenting with values I finally landed on 500K Log pots, 0.022uF tone caps, push-pull pots on the tone pots, 470K resistors wired at the switches on the tone pots for impedance matching on the coil split, and treble bypass circuits on the volume pots comprising 0.00047µF (0.47nF) ceramic capacitors and 330 kOhm metal film resistors in parallel.  I think it sounds best with these values and although there's plenty treble when needed, it's not overpowering and dials down nicely.  It sounds much better than it did as I bought it with the retrofitted 250K pots. 

Dave_Mc

ICBM said:

Dave_Mc said:

I'm not sure what an MIR capacitor is, I tried googling it and got nowhere!

One that sounds the same as all the others .

Mylar in resin, probably - they’re normally just called Mylar, although they are in resin. Pretty much all guitar caps in the 80s were either Mylar or ceramic so it’s the most likely.

 

Yeah that's a good call about the MIR.

@BillDL was lucky- when I tried it yesterday Google AI confidently started describing MIS transistors to me! I realise it's pretty easy to hit an "R" instead of an "S", but would I really have typed "capacitor" instead of "transistor" too? 

I actually tried it again just to see, and did a bit better this time:

 "An MIR capacitor is a specific, robust type of electrical component traditionally built to withstand demanding, high-voltage environments. Historically, many of these high-voltage capacitors were manufactured with chlorinated diphenyl (often referred to as askarel or PCB) oils as the dielectric because of their cost-efficiency and non-flammable nature. [1, 2, 3]

Because older designs utilized toxic and environmentally hazardous chlorinated diphenyls, the use of MIR capacitors has been heavily phased out. They have been largely replaced by safer, modern alternatives."

That's AI so no idea if it's right or not! Also I note it doesn't actually elaborate on what the "MIR" stands for so it may well still stand for "mylar in resin"!

@BillDL : I'm glad you posted that pic, I couldn't figure out what you meant by its being "see-through"! I was only thinking of the opaque dark green mylar (?) caps I've come across usually in guitars. But the pic made it clear- I'd forgotten but I think my MIJ Tokai Tele (a more recent one, mid-to-late 2000s maybe?) had a tone cap like that in it (but 0.047uF). Maybe they're Japanese caps?

Not surprised it sounds better with those values, those are basically the "standard" ones which I usually prefer too. I don't really like humbuckers with 250k.

ICBM

Dave_Mc said:

That's AI so no idea if it's right or not!

Classic AI authoritative-sounding nonsense when it has no idea what it’s talking about.

Dave_Mc

ICBM said:

Dave_Mc said:

That's AI so no idea if it's right or not!

Classic AI authoritative-sounding nonsense when it has no idea what it’s talking about.

Yeah it's kind of concerning... it's like they copied the most annoying people! "Most people will believe AI if we make it sound certain it's right!"

EDIT: Oh, maybe the "MIS" thing I was talking about was a capacitor, not a transistor. I went to Wikipedia (where I should've gone in the first place), and that came up. It has a layer of semiconductor, maybe that's what confused the AI yesterday (or maybe me if I misremembered since I couldn't find the original AI answer from yesterday!).

BillDL

MIS = Made In Scotland - from girders no doubt