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Archive for the ‘Capacitors’ Category

“When last we left our intrepid hero, he had just removed all the electronics from the ’08 Epiphone Les Paul Standard Plain Top.  In today’s exciting episode, we will be captivated as he prepares the guitar to receive the transplant, and creates a new wiring harness from scratch”.

Ok, that may be a bit mellow-dramatic, but I always did love the old radio shows.  Now that I’ve prepped the guitar by removing the old electronics, and I’ve prepped myself by adding a few of my favorite Blue beverages from our Canadian friends, it’s time to create the wiring harness.

One important difference between the harness that I just took out, and the one that I’m about to make is the shaft size of the pots.  Epiphone stock pots have slightly smaller shafts than the CTS pots.  In order for the new pots to fit, we need to enlarge the holes (Gibson uses different pots which require the larger hole, so this is not needed).  Some people have suggested using a reaming tool to enlarge the holes.  I feel that is overkill, since the holes only need to be worked a small fraction of an inch, and I feel the reaming tool may harm the finish (the Epiphone poly finish has a tendency to flake).  I prefer working the holes with 60 and 220 grit sandpaper.  Yes, it takes a bit longer, but the finished product is better.

You’ll need to open up the holes for the pots just ever so slightly. I use 60 and 220 grit sandpaper. Cut a 4×4 inch piece of both grits and roll them up. Put them in the holes and gently work the sandpaper up and down while slowly rotating the sandpaper in the hole. Start with the 60 grit, and constantly check to see if the pot fits. You don’t want to make the holes too big. When the pot just barely doesn’t fit in the hole, finish it off with the 220 grit sandpaper until the pot fits snugly, but is not tight.  Also, you won’t have to worry about hurting the finish.  It’s important to open the holes before you make the harness.  Since we use one of the new pots to check the size of holes as we sand them, you don’t want to move the completed harness around every time you want to check the holes.

The hole directly above the tailpiece has already been finished. You’ll see it looks clean and all the finish has been removed from inside the hole compared to the others.

We need to create a template of the pot holes so we get the spacing right when we build our new harness.  Take a blank piece of paper and tape it to the front of the guitar so the paper covers the holes for the pots.  Flip the guitar over and from inside the electronics cavity use a pen to draw circles on the paper using the holes as a guide.  Make sure you label which pots are neck and bridge, and volume and tone.  Remove the paper from the guitar and tape it to a thin piece of scrap wood.  This will become our template.

With the paper taped to the wood, and using a 3/8” bit, drill 4 holes through the circles on the paper into the wood.  Off to the side, away from the 4 holes you just drilled, drill a ½” hole to mount the toggle switch.

At this point I should probably talk about pot values and placement. Even the best set of matched pots from Jonesy or MSSC won’t all be the same value. Because of this, the experts have figured out where each pot should go. The pot with the highest value should be the neck volume pot to give the pickup as much clarity as possible.  Next should be the bridge volume, then neck tone, and finally bridge tone.  To get the value of a pot, use a multi-meter set to measure resistance.  Put the probes on the outer lugs.  The resistance shown on the multi-meter is the value of the pot.  Matched sets from several vendors will already be labeled with both value and placement, such as “NV” for Neck Volume.  You’ll have to measure the pots yourself if you order the pots from StewMac or Allparts.

Now that we know which pot should go where, put the pots in the holes.  The neck volume lugs should facing the neck tone lugs.  The goes for the bridge pots, too.  Finally, put the toggle switch in the hole. We don’t want anything moving while we have a hot soldering iron it, so put the nuts on the pots and switch and finger tighten everything down. Since we’re all guitar players here, we should have above average finger strength. 🙂

So, before we start soldering wires I’d like to state the obvious (my wife always says I have an amazing grasp of the obvious).  Test every solder joint as soon as you’re done.  Don’t go a few steps and then test.  Test immediately.  It will save you so much time in the end.  Also, make sure you test all the connections.  In places where you are soldering a wire to two lugs at the same time, test both lugs against each other and with the wire.  I cannot stress enough how important it is at this stage to take your time and constantly test, test, test!

I’ve always found it easier to start off slowly, so I wired up the switch first.  In the picture above, the two lugs coming off the left side of the switch will go to the jack.  On the left side, there are two lugs which will connect to the volume pots, and one big loop which is the ground.  Using a pair of pliers, bend the two lugs on the left together (opposite side from the ground), and then solder a 2’ piece of shielded wire to the lugs.  Next, we take 2 more pieces of 2’shielded wire and solder them to the lugs on the opposite side (one to each).  Now that we have the leads soldered to the switch, we need to ground the whole thing.  Since I’m using vintage push-back wire with an exposed braided shield, I took a 6” piece of exposed solid 22 gauge wire and soldered it to the grounding lug.  Then I wrapped the other end around the braided shielding of the 3 wires coming off the switch and soldered it to shielding.  While we are testing the switch to make sure it works as it should, it’s a good idea to label the wires for future reference (Neck, Bridge, Jack are the labels I use).

JonesyBlues has a great video on how to solder the switch as well (which is another reason why I like doing business with him).

With the switch done, and the soldering iron ready to go, I moved on to wiring up the pots with the caps and ground loop.  Since we’ll be soldering to the back of the pots, now is a good time to switch the tip on the soldering iron to the blade to provide a larger surface area to heat the pots quicker.  The next step is to ground the lugs on the pots.  For the tone pots, bend the center lug back until it is touching the pot casing.  You probably won’t get it all the way back, but get it as close as you can.  Now, solder the lug to the casing.  Be very careful that you don’t let any molten solder run down into the small holes in the pot casing.  This can kill the pot, or at the very least cause a “bump” in the action of the pot.  Do I need to tell you to test it to make sure the lug and casing have a good connection?  Didn’t think so.  🙂  For the volume pots, look at the pot so the three lugs are pointing down.  Bend the lug on the right backwards until it is touching the casing, just like tone pots.  Again, solder the lug to the casing.  Do this for both the neck and bridge volume pots.

Since I still had the blade tip on the soldering iron, next I created the ground loop between all of the pots.  I used a piece of insulated, not shielded, 22 gauge wire and cut it to size so it creates an arc around all four pots starting with the neck volume pot and ending with the bridge volume pot.  Strip the insulation from the wire at the ends, and in the two places in the middle where it will be soldered to the neck and bridge tone pots.  It’s perfectly acceptable to use a bare wire without any insulation as the ground loop wire.  Just make sure it’s tight, and can’t vibrate or move and short something out.  Since I don’t have the precision of the pre-made kits, I opted for some flexibility and used the insulated wire.  Once the ground wire is soldered to all the pots, use your multi-meter to make sure you have continuity from the back of each pot to the back of every other pot.

The last step is to solder the tone capacitors between the volume and tone pots.  Since this is delicate soldering work, I suggesting switching back to the fine point soldering tip.  Using the picture above of the pots on the template board, the tone caps go from the lower lug on the tone pots to the middle lug on volume pots.  Most capacitors don’t have any “directionality”, so it doesn’t matter which end goes on the tone pot or the volume pot.  When you’re done, you should have something that looks like this:

There you have it.  The switch and harness are wired, and ready to be installed in the guitar.  Next time we’ll finish off the electronics upgrade be installing the switch and soldering everything together.

Until next time, have another drink.  The more you drink, the better I sound.

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I’ve been fortunate to have a little free time to work on the guitars. As my loyal readers know (all 3 of you), I replaced the nuts on the eBay guitar and the Epiphone, and then replaced the nut on the eBay guitar again to get a better finish. I also spent some time researching guitar electronics including tone capacitors and potentiometers.  Today, it is time to upgrade the electronics in the Epiphone with new caps, pots, switch and jack.

In my previous post, I decided on vintage New Old Stock Paper-In-Oil .015uF and .022uF capacitors.  As for potentiometers, CTS 550K +/-10% pots seem to be the gold standard.  I also ordered some 1950s style wire to make everything look authentic.  The caps were ordered from MartinSixStringCustoms.com and the matched set of CTS pots came from JonesyBlues.com.  The wire, switch, and jack, I got from Allparts.com.

There is a decision to be made at this point as to the “style” of wiring.  In the most basic sense, there is 50’s wiring and modern wiring.  As I understand it, 50’s wiring preserves the highs when you roll off the volume, but adjusting the tone can affect volume.  This is what was used in the 50’s and 60’s.  Modern wiring is considered more “stable” in that there is less interplay between the tone and volume pots, but the downside is that your tone can become “muddy” at lower volume levels.  I opted for 50’s wiring to preserve the highs at lower volumes.

Now that we have all the parts, and we have the schematics for the wiring (thanks again to the MyLesPaul forums) it’s time to actually perform surgery.  Everything up this point has been small, lightweight modifications.  If I screw this up, it’s definitely off to the guitar shop to have someone else fix my mistake.

Before we begin, I’d like to apologize for the lack of pictures in this posting.  I didn’t realize how involved removing the electronics would be, and I didn’t take make pictures.  I promise I’ll make up for it when we put things back together.

Step one is prepping the patient for surgery.  I recommend removing the strings, bridge and tailpiece, and covering the pickup covers.  I didn’t do it, and I ended up with small scratches on the pickup-covers where the strings rubbed.  Fortunately, the pups will be replaced soon, so I’m not too upset.  Next, flip the guitar over and remove the toggle switch cover and the electronics cavity cover.  This is what my Epi looked like when I took off the electronics cavity cover.

Disconnect the wiring harness and clip the zip tie to let the wiring float free.  Be careful not to nick or cut any of the wires when cutting the zip tie.

Also, we need to remove the ¼” jack plate.  Make sure you keep the switch and cavity cover screws separate from the jack plate screws.  They are different sizes.  Once the jack plate is off, remove the jack from the cover and slide the jack inside the guitar.

At this point, I opted to remove the electronics from the guitar to make it easier to de-solder the pickup leads from the pots.  Flip the guitar over again so you see the front of the guitar.  Carefully remove the knobs from the pots to expose the nuts and washers.  Remove the nuts from the pots and gently push the pots into the guitar.  While we have the guitar right-side-up, remove the nut holding the toggle switch in place.  Once the nut is off the switch, the rhythm/treble label may come off, too.  Now that the switch and all the pots are free, flip the guitar over so you see the electronics cavity again.

Carefully remove the electronics from the cavity making sure to not put too much tension on any wires leading into the guitar.  These are the wires leading to the pickups and the bridge ground; in other words, the wires we’ll keep.

It’s now time to fire up the soldering iron.  A few important tips to keep in mind:

  • Use at least a 40 watt soldering iron.  We are soldering (and de-soldering) wires from the back of the pots.  The pots are larger pieces of metal and therefore require more heat.  Using a lower wattage soldering iron will “cook” the inside of the pot and ruin it while you are trying to get it hot enough to melt the solder.
  • Make sure you have both a fine point and a blade tip for your soldering iron.  The fine tip is for the leads on the pots, and the blade is great for working the back of the pots.
  • If you’re new to soldering, there is a great video here to get you started.

Got that?  Good.

We need to identify the 5 wires we are going to de-solder.  They are the ground and lead wires from the neck and bridge pickups, and the ground wire from the bridge.  The pups wires are actually a wire within a wire (shielding), so don’t go looking for 5 separate wires, you’ll only find 3, but there are 5 places we need to de-solder.  On my Epi, the bridge pup wire was black with a white lead inside, and the neck pickup was red with a red lead inside.  The bridge ground was a single black wire.  Yours could be different.  I circled the bridge pup ground and lead in the picture below.  The neck pup ground and lead are soldered to the pot immediately to the right in the picture, but are obscured by the bundle of wires in the middle.  To orient yourself with the picture, the neck would be above the top of the picture, and the lower strap button would below the bottom of the picture, and you can see the jack plate in the lower left corner.

Once you have the wires de-soldered and because we already disconnected the clip and zip tie, the old harness should be completely free so you can put it off to the side.  Next, we need to remove the pickups by removing the 4 screws holding the mounting rings.  Since the pickup wires are no longer soldered to anything, the pups should come right out.  Again, keep the mounting ring screws separate from the other screws.  They are a different size.

With the pickups out, it should be easy to remove the switch.  Start by pulling the wire that goes to the switch out of the guitar until it is hanging out of the neck pickup hole, and then slowly work the switch out of the cavity, pulling the wire with it.

There you have it, a beautiful Epiphone Les Paul without a single piece of electronics in it.  At this point, it might not be a bad idea to take a break.  I know I need one!

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With the new nut on the guitar and feeling good about working on it, it was time to turn my attention the electronics. The electronics are the heart of any electric guitar (shocking, I know), and the quality of the parts can make a big difference in the tone. Not being one to just jump into things (except, maybe, marriage.  Long story), I took my time and did a considerable amount of research. I found out that one of the biggest contributors to the tone of the guitar are the tone capacitors, or caps, for those in know.

Learning about tone caps is enough to make your head spin. There are almost as many opinions of which is the “best” cap as there are capacitors. The two factors in selecting a cap are the capacitance value, and the construction of the cap. Some people say the value is all that matters, but we’ll get into that a little later.

For a Les Paul, the stock values of the caps are .022 microfarad, or uF, for the neck and bridge tone circuits(yes, the u should be a different symbol, but I can’t figure out how to make it).   One common upgrade is called the “Woman Tone”, and it consists of swapping the neck .022uF cap with a .015uF cap.  The difference is how the highs are rolled off when you adjust the tone knob.  After hearing a few sound clips, it was an upgrade I wanted to do.

Another specification you’ll see for capacitors is voltage.  Guitars are very low voltage devices, so there is no difference between using a 100V, 400V, or 600V capacitor.  They will all sound the same.

Now that I know what values of caps I’m going to use, I needed to figure out what the caps should be made of.  Here is where things got interesting…

The most common types I found in my research are Mylar, ceramic, polypropylene, and paper-in-oil (PIO). Back in the olden days of electric guitars, the 1950’s and 1960’s, paper-in-oil was the choice of Gibson. Mylar caps hadn’t been invented yet, and I don’t know if ceramic was around yet, either.   I know polypropylene wasn’t an option then.  This left paper-in-oil.  Of the PIO caps, three models were the most common on Gibsons: Gray Tiger, Black Beauty, and Bumblebees. Original Bumblebees seemed to be the “holy grail” of tone capacitors, and if I wanted my Faux Paul to sound like the original, then this is what I was going to get. Then I saw the price. A set of original Bumblebee caps pulled from an old Les Paul can set you back several hundreds of dollars, Gibson sells reproduction Bumblebees for almost $100, and I’m always wary of anything that says “reproduction”. Wow! Ok, so maybe I should find something close, but slightly less expensive (say $10).

Fortunately, there are a plethora of sites that have done the hard work for me. I’d like to extend a huge thanks to the guys at PlanetZ, Kernel of Wisdom, and the MyLesPaul forum for all their help. The guys at PlanetZ built something they call the “Crazy Tone Thing“. Basically it allows you to sample several capacitors without having to rewire your guitar to swap them out. Kernel of Wisdom had multiple capacitor shoot-outs, with labeled and blind tone clips. That was super-helpful in letting me really hear the different caps and search for the tone I wanted. Also, the guys at Kernel of Wisdom dissected a few of the repro caps, with very interesting results. The people over at the MyLesPaul were exceedingly helpful in providing real-world experience with various caps.

So after reading about all the different caps; what’s under the hood of the reproductions (some of the expensive repros are actually modern $.50 caps with fancy shells); and listening to what they really sounded like, I decided on vintage paper-in-oil capacitors. I especially liked the Aerovox and Russian K40Y-9 caps. Vintage caps comes in 2 flavors – New Old Stock, or NOS, which means they were never used in anything, and are, therefore, “new”; and “pulls”, which means they were pulled from on old piece of electronics. I strongly recommend NOS, since you never know how much life is left in a pull.

Some people say you can’t hear the difference between a $.15 modern capacitor, and a NOS paper-in-oil cap.  I disagree.  After listening to the cap shoot-outs more times than I care to remember, I could hear subtle differences in the tone and how the tone rolled off.  I could hear a little more warmth in the old caps.  It’s debatable whether most people be able to discern the difference, but to my ears I could hear it.  Also, it’s not like it was going to cost me an arm and a leg to get the caps I wanted.  I finally decided on an Aerovox NOS PIO .022uF cap for the bridge and a Russian NOS PIO K40Y-9 .015uF cap for the neck.

Now that I’ve chosen the value and construction of the caps, I had to find them somewhere.  It’s not like I could run down to my local RadioShack and ask them if they had any capacitors left over from the Cold War.  Fortunately, there are several places you can find them on-line.  My two favorites are JonesyBlues and MartinSixStringCustoms.  I’ve ordered parts a few times from each, and both are great to work with.  They each carry different stock, so if one doesn’t have what you’re looking for, go try the other.  I got my caps from MartinSixStringCustoms, and they arrived 3 days later.

With caps in hand, I formulated my plan to replace all the electronics in the guitar.  Stay tuned, next time we’ll put it all together with some vintage wire and some pots.

Have another drink.  The more you drink, the better I sound.

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