This 1970s Japanese 130 is in a right old sorry state. It has a pretty bad belly hump behind the bridge. 40 years of string tension (200 lbs with medium gauge strings-!) is pulling the rosewood bridge towards the headstock and taking the rest of the top with it.
The main symptom of this being the action is so far away from the frets the guitar is totally unplayable.
This is the second Yasuma I’ve worked on this year. They have loads of Japanese MOJO and sound just as good as the highly sort after Yamaha red label guitars of the same era. This 130 is another Martin D28 copy. The neck is V shaped and the whole guitar is finished in nitro cellulose lacquer – something not found on mid priced guitars manufactured today.
In the 1970s Japanese manufacturers began to get more serious with companies even attempting to pass themselves off as American brands such as Martin. These were high-quality and looked too close for comfort to the real thing. The Yasuma Musical Instrument Company was one of many who fell foul of US litigation and were ultimately put out of business.
The solution comes from JDL Guitars in Roswell, New Mexico – but probably not back engineered alien technology from a crashed space ship.
“The JDL bridge doctor fits underneath the bridge inside the guitar and is adjusted to counteract the pull of the strings and the soundboard distortion. The top is pulled flat and a playable action has been restored. The strings exert proper downward pressure on the saddle – enabling them to transmit more vibration to the instrument. The Bridge System is also acting as a soundpost – transferring string vibration to the body woods directly from the bridge.
Aside from a small bridge hole, the guitar is completely unmodified and is not only easy to play, it will now have more volume and sustain and a richer tone than it ever has before.”
One small screw in the centre of the bridge. Later will be countersunk and covered with MOP inlay.
A shot of the inside. The bridge doctor is then tensioned using an allen key.
Now the action is a little lower the frets can be dressed and the guitar setup correctly.
Leveling the top of the frets. This guitar has been re-fretted with Gibson jumbo gauge wire.
After leveling, re-crowning and several different grades of micro abrasives, the frets start to get shiny.
As you can see here the bridge is now at the correct angle with out the body hump that was tilting it forward.
All strung back together.
UPDATE 1:-
Glen from Toronto sent through a few pictures of his Yasuma Newance with a very similar belly hump.
UPDATE 2:-
John Sterry sent through a few pictures of the Yasuma Newance he picked up on Gumtree. Quite a bargain !
Thank you for this information. You have likely changed my mind from a neck reset. Question, do you need to humidify the guitar first (for a week or more) to help pull down the belly?
Hi Travis, Removing the strings from the guitar should be enough to lower the belly. The strings had been off this for about a month and the top pulled flat as soon as I installed the bridge doctor. You shouldn’t need to humidify the guitar. I did have to take the bridge and the saddle down quite a bit, so you may still require a neck reset on yours – but it will certainly cure the problem with the belly. Cheers John.
Travis is the bridge plate OK on the guitar? If it is worn it is possible the ball ends of the strings are actually distorting the maple top taking the bridge with it. You could try a Plate Mate: http://www.stewmac.com/shop/Tools/Special_tools_for_Bridges/Plate_Mate.html
I have had a Yasuma Newance Model WG130 for 40 years and it still sounds as good as ever but as time goes by it get more battered but I would never part from it, The neck is thin and easy to play with small fingers. I bought the Guitar from Dave Ditchburn who played in a band called Brass Alley in the North East of England(Dave can still be seen on you tube to this day ) I paid Dave £15 in 1974