New Luna Ukulele Is Bent Out Of Shape

Sophie’s aunt wanted to do something to further her niece’s continuing education and eventual career in music therapy.  This nice Luna ukulele was a thoughtful gift.  Unfortunately, there were many dead notes.  Could the Unbrokenstring Crew bring those notes back to life?

Inside the bag is a ukulele, some picks, a tuner, and an instructional DVD!

 

The words for “Peace” in forty-four languages are engraved into the soundboard of this instrument. All you hippies will recognize the peace sign in the sound hole.

 

Sure enough, there are several notes on the fret board, near the nut, that are muted out.

 

Name, rank, and serial number, please.

 

I am not sure what this number is…

 

The fret rocker shows a very tiny difference in fret height, when checking between adjacent frets.

 

However, a straight edge reveals that the neck is back-bowed. The tape just keeps the machinist’s scale upright so I could take the picture.

 

I recorded the string height for all posterity. This is not far from right for a ukulele. Some authorities say it’s too high, others say too low. Whatever.

 

The fret wire height is not adequate to support a fret level job. The back bow is just too much. Yes, the back bow is more than 0.040 inch on each end of the fret board!

 

My guess is, the fret board will need to be reshaped. Here, I’m recording the width of the fret wires.

 

Concert ukuleles are tuned A – E – C – G, with the bottom string, sometimes called String 1, the highest pitch. This G string diameter is about 0.022 inch.

 

The C string is about 0.030 inch.

 

The E string is the largest, measuring about 0.035 inch.

 

The drone string is tuned to A above the G. This string measures about 0.025 inch.

 

Interestingly, the fret board has about a 20 inch radius, while the nut and saddle are absolutely flat. The Luna Guitars Web site specs this instrument with a flat fret board, too. I’ve decided to re-flatten the entire fret board. The nut must come off. Here, I’m cutting the finish so that the nut can be removed cleanly.

 

I love whacking musical instruments with a hammer. I find it strangely satisfying.

 

The saddle slips out of its slot. You can see that there is no radius in the saddle at all.

 

The Smoking Gun. There is not enough string tension in the world to straighten this neck. It also has a twist. It doesn’t matter that this instrument has no truss rod because it wouldn’t help.

 

Visually, we can see the wavy fret board and a clear radius. How did this instrument leave the factory?

 

Let’s get the tuners out of the way.

 

I made this fret remover from an inexpensive set of end nippers from Harbor Freight.

 

These frets over the body are easily removed.

 

Before the woodworking begins in earnest, let’s tape everything off.

 

Some cardboard protects the entire soundboard.

 

The strategy is to flatten the fret board on the belt sander.

 

This little belt sanding station came from Harbor Freight.

 

Some of the safety covers were removed to enable the instrument to set flat on the sanding belt. Do not attempt this at home, kids!

 

The eighty-grit sanding belt begins to make an impression on the fret board. This fret board appears to be rosewood, but the Web site says that this instrument is all mahogany. Dunno about that.

 

With a twist that bad, we can easily inspect our progress.

 

Now I am wondering what I got myself into.

 

Back to it! Many thanks to my wife Glenda for taking these pictures.

 

Serious amounts of sanding dust are produced, so we are outside today.

 

Another check shows that we are not there yet.

 

The sanding belt is doing its work.

 

What is it going to take to get this straight?

 

Sanding dust is going everywhere. No scorch marks yet!

 

I am pleased that the fret markers are still intact.

 

Very light pressure is used now to clean up the surface.

 

Now we’re getting somewhere.

 

Continuing on, producing sanding dust like crazy.

 

Now I’m thinking that I need to be careful not to go too far.

 

Most of the fret board is flat. There is still some fall-away over the body of the ukulele, which is OK with me.

 

Last few strokes on the belt.

 

The twist is gone and most of the fret board is absolutely flat. I thought that the noise of sanding would drive the cats away, but we see Jack on the bottom step in the lower left corner of this picture.

 

The luthier’s scraper shows that the fret board is flat.

 

The sharp scraper is an excellent tool to finish raw wood.

 

The fret slots at fret six and seven are almost gone. I really don’t think that this fret board is mahogany.

 

Fret slot ten is almost gone.

 

One end of the fret slots over the body IS gone. Yes, it was that bad.

 

My fret saw was set to 0.054 inch, which is the depth of the new fret tangs.

 

Every slot was taken down to about 0.055 inch.

 

These short sections of small fret wire are perfect for this instrument.

 

Each fret was installed, and nipped to length after installation. The long ends were the pieces at the end of the short strips that weren’t long enough to fill another fret. They get nipped off separately.

 

After nipping, this file embedded in a block of nylon files the fret ends 90 degrees to the fret board. Moving the file to another slot allows the fret crowns to be filed to a 60 degree angle to the fret board. I love eBay!

 

Checking for flatness, these frets are ABSOLUTELY flat, which is not surprising.

 

The fret ends are shaped and burnished by hand, and the fret wires are lightly sanded. As with a classical guitar, the frets are not polished, but finely sanded in the same direction as that of the string.

 

The original nut was reused, and re-slotted to restore the original 0.060 inch string height. The nut was just right as it was. The fret board was oiled. New strings complete the job. All the notes are present and accounted for!

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE

281-636-8626

Gibson ES125 Tune-Up

Dr. John has collected this beautiful ES-125 (a Gibson Electric Spanish guitar with an MSRP of $125 back when it was produced) but it sounded as if it were underwater. Could the Unbrokenstring Crew toss it a life saver?

 

This instrument is in collectable condition, with all original hardware. The finish is finely-checked as you would expect a seventy-year-old musical instrument to be. A new hand-wound pickup was included in the instrument case, if the original one was defective and could not be easily fixed.

 

Years of oxidation and skin oil had made the neck sticky, particularly when the humidity is high (which is all the time in Houston.)

 

The sticky finish ends at the head stock, which implies that the finish is OK but the skin oil is the culprit.

 

Here, fine polishing compound is mixed with Dr. Duck’s Axe Wax to rub out the finish and remove the oxidation.

 

Next, we will look under the pick guard to investigate where the underwater sound is coming from.

 

This pick guard is shaped in such a way that it holds all the controls, and only a hole for the ground wire to the bridge and a slot to clear the pickup is needed in the sound board to electrify this instrument.

 

The ground wire to the strings appears to be a piece of lamp cord. The solder joint around the ground wire did not alloy to the ground wire between the pots, but slides up and down the wire.

 

This ceramic cap is the tone cap. It bleeds off high frequency to ground under the control of the tone pot.

 

This tone cap is marked 0.02uF at 50 volts.

 

On the capacitor tester, the value is correct.

 

However, the dielectric is very leaky, which would probably change things in the tone circuit for the worse. This is probably where the ‘underwater’ sound comes from!

 

Some high quality film capacitors are retrieved from stock.

 

These are the same value, 0.02uF, but are rated at 400v in case the guitarist plugs the instrument into a wall socket. At least the capacitor will survive. The player, not so much…

 

Dr. John lives about seventy miles away. As each change was made, a sound file of the instrument was emailed to him to monitor progress.

 

A free copy of ProTools First and Ableton Live came with the interface, which will amazingly run pretty well on this old rack-mount controller PC that I have on the bench.

 

John decided that the new pickup didn’t add anything to this fine old instrument, so it remains in its original condition as of seventy years ago (with a new tone cap, of course.)

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE
281-636-8626

Epiphone PR-5E Acoustic Gets New Electronics

This wonderful instrument was rescued from an abandoned house.  It sounded good acoustically, so the new owner asked if the Unbrokenstring Crew could repair the electronics and get it playable again?  Let’s get to work!

This instrument is only a few years old, purchased and then cast aside.

 

An online source for specialty guitar parts had a 2018 model of the electronics.  Can we make it work?

 

The mounting scheme uses four screws in the corners.  Cleats will be added to the guitar so that the screws hold.

 

But the REAL advantage of the 2018 electronics is that the enclosure matches the curve of the body.

 

Common wood items such as yard sticks, tongue depressors, popsicle sticks, and paint stirrers are made from birch, the straight-grained ‘poor relation’ to maple.  So the paint department lady at Home Depot gave me this stirrer.

 

Cleats to tightly hold the electronics in the body are fabricated by hand.

 

Next, the cleats are sanded to fit the curve of the body on the inside of the bout.

 

These are ready to trial-fit.  The bevel on the corner, lower-left side, clears an internal brace in the guitar.

 

One shim goes here.  Note the angled pieces, which will catch the screws in the electronics.

 

To protect the finish, low tack painter’s tape is used all around.

 

These clamps will hold the cleats in place as the hide glue sets up.

 

Both cleats are installed and the hide glue is curing.

 

Additional reinforcement is added in the corners to give the screws more material to grip.  These bits will be in compression, so they don’t need to be super-strong, only tough.

 

Before we get too far, we need to do another trial fit.

 

I think we’re going to be good here!

 

I will pre-drill the holes where the screws will be installed.  This should minimize splitting of the small cleats.

 

The actual drilling will be finger-powered, using this pin vise.

 

All four holes are pre-drilled.

 

Yes, I know.  This isn’t terribly interesting.

 

The screws are installed.  Not bad!

 

The jack plate holds the battery and has both 1/4th inch phone plug and balanced XLR connections.  It was temporarily removed to give more access to the interior of the instrument.  The new electronics hook right up to the jack plate.

 

This is a new one on me.  This battery was in the guitar when it came in.  The Golden Thumbs-Up Emoji Award!

 

And, while we’re here, we’ll clean the instrument, string it, and do a setup.

 

The electronics come alive!

 

This is a cool tuner.  The LCD screen has a pointer that swings across its face.

 

Beauty is skin-deep, but what really counts is just below the surface.  This rescued guitar is ready to make music!

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE
281-636-8626

Jasmine Classical Guitar Needs a Setup

Sophia’s classical guitar had developed a buzzing string.  Perhaps the humidity changes had changed the geometry of the instrument.  She immediately called The Unbrokenstring Crew to take a look at it!
This instrument has a truss rod, something a little out of the ordinary for classical guitars.

 

This is an Indonesian instrument, with lots of mahogany throughout.

 

Using the truss rod adjustment, we make the fret board as flat as we can get it.

 

My Super Duper Absolutely Flat sanding bar goes to work on some high frets.

 

Can you see where the metal has been removed?  This is near the tenth and eleventh frets.

 

One side of the fifth fret was particularly high.  This was the source of the original buzz.

 

The wreckage was bad over the body of the guitar, where the fret board was probably glued straight to the sound board.

 

Before we crown the frets, the fret board will be taped off.

 

To clean and condition the fret board, Dr. Duck’s Axe Wax goes to work.

 

These strings are going back on the instrument.

 

The strings are nicely tied off at the block here.

 

The stringing process is documented in earlier blog posts.  Everything is going well here!

 

Sophia performs live while standing.  So, we’ll add a strap button to the instrument lower bout here.

 

The hole for the pin clears the body of the screw.

 

This strap pin is just above the center line of the instrument. so that it will hang flat against her body.

 

This strap pin is from an inexpensive electric guitar that had strap locks installed.  It goes nicely with the binding.

 

At her favorite venue, Dunn Brothers Coffee in Friendswood TX, Sophia tunes up with an app on her phone.  Life Is Good!

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE
281-636-8626

Red Ibanez A200 Acoustic Electric Guitar Gets Fixed Right

Sophia called The Unbrokenstring Crew after her prized red Ibanez acoustic/electric quit during a gig.  Could we fix it?

This is a surprisingly solid instrument, with a red finish that just won’t quit.

 

I also have a similar Chinese acoustic electric which is a surprisingly good guitar for the money.

 

The tuner still worked although the output from the guitar was silent.  Therefore, the problem is between the electronics and the output jack.  The electronics and tuner are removed to gain access.

 

That didn’t take long to find.  Someone had just soldered the wire to the connector pin.  This eventually flexed and failed.

 

The other end of the broken cable goes to the output jack.  The balanced output jack is a nice touch.

 

Let’s try to take some pics inside the guitar.  But we need more light.  This LED flashlight will do the job.

 

This is inside the guitar.  The wire tie holds the harnesses in place so that they don’t rattle while the instrument is played.

 

I didn’t need to remove the piezo pickup, but I’m taking it out of the guitar anyway so that it is not damaged.  The pickup and the tuner are one piece, so we can store them all safely while other work proceeds.

 

Meet Ms. Output Jack.

 

The broken cable solders to the circuit board.  The location and function of the wires is recorded in the notebook.

 

The unbalanced TRS output jack is wired to the circuit board as shown.  This picture is for documentation purposes.

 

Can you see a problem?  The TRS output jack should fit down inside bosses molded into the body of the output jack assembly.  Whoever tried to fix this before installed the TRS jack 90 degrees out from where it belonged.

 

This is the end of the broken cable.

 

A new cable was secured from a guitar junkyard on eBay.  Looks the same, doesn’t it?

 

The old cable was desoldered and the new one installed as shown.  We are ready to solder the wires to the PCB.

 

Soldering complete.  Note that the TRS jack, on the right, is correctly installed now.

 

The output jack goes where it belongs.

 

Before we install the electronics, let’s show a little love to the bridge with some Dr. Duck’s Axe Wax.

 

The new cable installs as shown.  I think this pic was taken while I was still testing everything out prior to reassembly.

 

I forgot to ask Sophia what gauge of strings she wanted.  These are probably 11s.

 

A phone call confirmed that these were what she wanted!  This guitar is repaired better than it was when Sophia purchased it.  The Unbrokenstring Crew makes the world just a little better than it was before.

Thanks for reading all the way to the end!

CONTACT – David Latchaw EE
281-636-8626