B-Band Mystery

Special thanks to my friend and teacher Mike McConville (http://mcconvilleguitars.blogspot.ca/) for referring one of his customers to me.  It saved the owner of this beautiful vintage Gibson D-45 some considerable travel time.

This guitar has the acoustic B-Band under saddle pickup system installed.  It developed some issues a while after it was installed, in that an audible and annoying popping sound was heard whenever the lower bought was jostled or knocked.  A tricky thing to pinpoint in the modern printed circuit board preamp systems...

You can see some of Mike's handywork here.  D-45's of this era came with the tone-sucking adjustable saddle, which had two threaded posts at either end of the saddle.  Mike used a piece of matching rosewood to fill the space then routed in a conventional saddle, hand made from a bone blank.  This is the only way an under saddle pickup system can be installed in these guitars, not to mention the fact that the guitar sounds 100% better!

Here is a view from under the saddle.  You can see the B-Band cable has been routed through the threaded post that previously held the saddle adjustment ~ clever!  It did move around quite a bit inside it though, so I carefully inserted a small piece of cork to stabilize it in the hole.

A preliminary check revealed no loose or shorting connections or electrical anomalies.  Considering the noise was generated from the lower bout, it was time to open the preamp ~ which in this case is attached to the back of the jack...

After removing the assembly I left it connected to see if I could coerce the unit itself to make the popping noise.  It didn't take long, and the culprit turned out to be the battery connector that housed the red & black wires from the 9v power supply.  I noticed someone had put a drop of super glue on the connection, but it obviously didn't fix the problem.

After a little more wiggling I noticed that the black wire sat firmly in place, but the red wire shifted slightly (approx 1/32") within the connector housing.  With the amp on I wiggled it again and sure enough it popped every time.  The red wire wasn't crimped tight enough within the connector, and it moved just enough to cut power momentarily whenever the guitar was jostled.  No wonder the owner was frustrated!

Super glue to the rescue!  A little drop in the hole at the top and back of the black connector did the trick, then the connector itself was cleaned and crimped slightly tighter.  Certainly something to check for when installing or inspecting these systems.

2001 Strat Truss Rod seized

This US made player's Fender Strat was brought in with concerns that the truss rod may be seized or at the end of it's threads.  It's also in desperate need of a fret dress.  As usual, I conducted a preliminary inspection and something jumped out at me right away ~ can you see what it is?

Notice the alignment of the strings?  At the 12th fret, the low E was 3/16" closer to the edge of the fretboard and the high E was 3/16" further away.  You can see it clearly where the strings align off-centre over the pole pieces of the pickups.  This will need some further investigation...

A quick way to check is to remove the D string and pinch it between the 3rd and 4th saddles, then hold it taught at the middle of the nut.  The string should align perfectly centred down the fretboard, and you can use the inlays as a guage...

At just the first inlay you can see how off-centre it is with the string riding slightly higher than the centre of the dot.

It's the opposite at the 15th to 19th frets, where the string rides slightly lower than the centre of the dots...

Unfortunately I didn't have another Strat on hand to compare, but mounting the neck on a known good body would help the process of elimination.  Using some schematics I found online of Strat routing measurements, and considering the neck itself is perfectly straight, I was able to determine that it is most likely the neck pocket being slightly off.  We'll have to see what the owner would like to do, as this makes a perfect set-up near impossible with this compound radius neck...



Now for the truss rod...
A close-up inspection of the nut shows a considerable amount of debris compacted in the allen-key adjustment nut.  Using a scribe and some contact cleaner I was able to loosen and remove it.










Just to be sure, a few swabs put the finishing touches on it and I could now see the nut clearly ~ and the allen-key now fit perfectly too!


I was now ready to see if the truss rod would turn ~ and it didn't!  But with a little added leverage it did move back & forth slightly.  Perhaps a little heat will loosen it up...

Inserting the allen key firmly then holding a high-heat soldering gun to it allowed enough heat to transfer to the truss rod threads.  This is a gradual process, but with a little time the nut was unseized and moved smoothly.  A little mineral oil to keep it that way will do the trick for another ten years!

During set-up I noticed that the saddle on the low E was almost flush against the bridge plate ~ a clear indication that the neck angle is off..

You can see how the end of the neck dips slightly into the body.  While this can eliminate some buzzing, the proper way to set it up is to keep it as level as possible so the saddles have some travel and adjust the bow of the neck to alleviate buzz.  This particular Strat has the "micro-tilt" adjustment in the heel of the neck plate, which can back off over time with so much tension on it.  This is a very minor adjustment that can have a major affect on playability.  After a fret dress and set-up, this axe was ready for action!