Help: Best way to join pickup wires of grossly dissimilar diameter for soldering?

[Mango Moon]

Hi Folks,

I've got a couple of brand new P90s that I'd like to install in an arch top, and I've done my fair share of soldering over the years including pickups of various kinds, but I am completely stumped this time around with how to make proper connections on these two P90s.

I don't know if its a phenomenon that is unique to P90s or what, but the two primary pickup wires (+ and - or ground) are literally "microscopic" in diameter. The outside diameter (OD) of the insulated wires measure less than 1mm and the stranded copper core (comprised of no more than 4-6 tiny copper strands) is something on the order of 1/100th of an inch (0.25-0.30 mm) in total diameter (?!@#$%&?). Worse yet, the limited number of ultra-fine internal copper strands (the conductors themselves) are super-fragile - any repeated manipulation at all and they readily break.

Now, I'm no engineer, so I won't question 'why' (or 'whether') such microscopic-scale wire is necessary for such applications, but I'll say this much . . . I've never seen wire this small in all my travels, and more importantly, I have absolutely NO idea how to reliably join or solder such tiny, fragile wire to another that is nearly FIVE TIMES as thick (i.e., the 22 awg solid core wire used by Fender, Gibson, PRS, and most other guitar manufacturers in their wiring harnesses).

Can anyone give me some pointers on this in terms of a suggested joining and soldering technique? How do pickup builders 'expect' such connections to be made? And how can I limit the risk of future breakage once installed? Its just a real uneasy feeling.

Thanks

[David Schwab]

Are you trying to solder the copper coil wire to a hookup wire? Or the hookup wire to the cable?

For the magnet wire, I twist it around the tinned end of the hookup wire about a dozen times, and then solder it, making sure it gets good and hot and that the solder flows evenly.

For the hookup wire to the lead, just twist the ends together and solder.

[Steve Conner]

Just twist the wires together and solder. If you're worried about breakage, you can reinforce the joint with heat shrink tubing.

Or electrical tape, if you know nobody will be looking.

[Mango Moon]

David,

Thanks for responding. I'm not sure about the terminology that is typically used to describe these different wires, but let me see if I can clarify things a little bit.

Each of the two pickups shipped with two, very tiny insulated wires (+/red & -/white), both surrounded by a spider-web of uninsulated (bare) stranded copper shielding (I'll call this shielding "black"), all three of which are encased in a single (larger) black insulation. For the sake of conversation, I'll call these three leads the "pickups" wires.

Unfortunately, when threaded through the necessary portals in the routing, the overall length of this bundled set of "pickup" wires was too short to reach all of the necessary solder points for the respective wires (i.e., volume and tone pots and/or 3-way switch, etc.). In addition, the four pots, the 3-way switch and the 1/4" output jack were all of low-grade quality, so I opted to craft an entirely new custom wiring harness with all new CTS/CRL/Switchcraft hardware, which has an open-ended pair of +/- (red/black) 22awg solid-core wires for connection to the +/- leads (pickup wires) of each pickup. These heavier gauge wires may be what you've called "hook-up" wires (above), but to eliminate any confusion here, I'll call them "harness" wires.

Now, the manufacturer's instructions indicate that the red (+) or primary "pickup" wire should connect to the red "harness" wire, and that the two white and black "pickup" wires, should be twisted together and connected (soldered) to the black "harness" wire. Thus, there would be a total of four (4) solder points (two for each pickup) in which an extremely thin (~0.01") and fragile stranded copper wire (i.e., the "pickup" wire) is soldered to the end of a much larger (22awg) "harness" wire. It is THIS set of four soldered connections that I am struggling with.

I don't know why they needed to be so incredibly small and fragile, but once stripped of their insulation, any manipulation of the tiny copper "pickup" wires is causing them to fragment or break, and if I tin their terminal ends first, in an effort to prevent this, then the "pickup" wire becomes too brittle to wrap around the "harness" wire.

At this point, due to breakage, I've already lost perhaps 1.5-2.0" in total length of each "pickup" wire, just messing around with them, but I'm wondering now whether the following approach might work best for joining each connection:

1) Carefully strip about 1" of insulation off the end of each wire (pickup wire and larger harness wire);
2) Tin the terminal end of each;
3) Place them side-by-side, but coming from 180-degree opposing directions such that the fully-tinned 1" length of each is in contact with the fully-tinned 1" length of the other;
4) Cut a short (2") snippet of very small or fine gauge bare copper wire;
5) Carefully wrap together the pair of tinned ends of "pickup" and "harness" wires that are adjacent to one another, using the snippet of bare copper wire;
6) Heat and firmly solder the entire assembly or bundle together;
7) Slide previously installed heat shrink tubing over the assembly and seal the connection/tubing with heat gun.

What do you think? Would that be a good approach? Or do you have any other (better) suggestions?

Thanks again.

[Mango Moon]

Steve,

I missed your comment here before adding my most recent posting, but yes, breakage is the central issue. The ultra-fine pickup wires are super fragile and ridiculously small in diameter, so that's what's presenting problems for me. The tiny copper strands of the stripped pickup wires cannot even be twisted without significant breakage.

Basically, once the insulation is gingerly removed from the ends of the pickup wires, the very limited number of internal strands of copper (maybe 4-6 in number?) are breaking off, even during gentle twisting. Its proving to be a real nightmare! I believe I'm going to need to tin the ends immediately, even before twisting them.

[big_teee]

Steve,

I missed your comment here before adding my most recent posting, but yes, breakage is the central issue. The ultra-fine pickup wires are super fragile and ridiculously small in diameter, so that's what's presenting problems for me. The tiny copper strands of the stripped pickup wires cannot even be twisted without significant breakage.

Basically, once the insulation is gingerly removed from the ends of the pickup wires, the very limited number of internal strands of copper (maybe 4-6 in number?) are breaking off, even during gentle twisting. Its proving to be a real nightmare! I believe I'm going to need to tin the ends immediately, even before twisting them.

Tin them first thing.
Then be gentle soldering them to the other wire.
You may have some bad wire.
Good Luck,
Terry