CGW Tech Talk: 2007 Jackson DK2M

For my first write-up on the CGW Tech Talk blog, I present to you one of my own guitars - this fantastic 2007 Jackson DK2M. For the record, let it be known that I am a Jackson fanatic. I have a tendency to nerd out pretty hardcore over Jackson instruments, so I feel like this is a great place to start things off on this blog.

This particular DK2M model was produced from 2006-2010, built in Japan. These guitars featured an alder body, maple fretboard, black binding, black sharkfins, and an unpainted headstock with the black binding, and a black logo. I believe they originally came with the Custom Custom/Jazz pickup set, but this one has an unstamped pickup out of a Charvel, and a DiMarzio PAF Pro in the bridge, which I installed. The current DK2M model (since 2012) has a few differences from these. I haven't seen very many of these older DK2Ms around, and I'm happy that I managed to snag one! This one, however, needed a bit of work done to the tremolo system, and I have explained it all in this write-up.

PROBLEMS:

The Floyd Rose-licensed tremolo was not returning back to 100% pitch after being used, mostly after rebounding from dives. Pulling back up a touch after diving would return it to pitch, but the plain strings would be pulled out of tune. Obviously, this is a problem. After spending a good bit of time with it, I found the problems causing these. We can't have a sleek Japanese shred machine going out of tune, can we?

CULPRITS:

1) worn-out trem springs. The springs that were in this guitar were a mismatched set, with different tensions. This is one of the easiest problems to address on these Floyd Rose systems.

2) worn-out and deformed contact surfaces on the bridge posts. They were mangled and deformed from presumably years of metal-to-metal contact. This was causing issues with the bridge pivoting exactly where it needs to, and would throw tuning off upon returning to a resting position.

3) worn-out contact points on the bridge's base plate (also known as "knife edges"). Of course, these were also mangled and deformed from frequent use. Long-term metal-to-metal contact on the knife edges and bridge posts will cause this. This is not as frequent of a problem on the higher-quality trems, like an actual Original Floyd Rose, or a Gotoh. These licensed bridges still work well, but the metal quality isn't quite up to par as the others, so you may encounter some wear and tear like this guitar has.

4) saddle insert blocks were worn. Easy fix. The old inserts were pretty thoroughly grooved from years of string changes. This would cause minor string slippage while actuating the trem, which would result in a drop in tuning on that string.

5) the locking nut had deep gouges cut into the bottom, from the strings. Additionally, the locking blocks also had deep string cuts. This caused the plain strings to be pulled out of tune while using the trem, even while the nut is locked down. An easy diagnosis of this is to use a tuner, and apply pressure on the string behind the nut. The tuner responded accordingly, which lets us know the string is in fact sliding through the nut.

ACTIONS TAKEN:

Trem posts were replaced with brand new Floyd Rose-brand posts and inserts from StewMac. Since the contact spot on the posts were worn and deformed all the way around, brand new inserts and posts were installed.

The contact points on the trem's knife edges were worn and mangled. Combine that with the worn out posts, and the pivoting points on the trem were not fully engaged smoothly, causing irregular operation and contributing to the trem not returning exactly to its original position.

(It is a bit hard to truly see the misshapen nature of the knife edges in this pic - better pics next time, sorry!)

I took a small file to these knife edges, and restored them to a good, sharp edge (ideally, you want the edges to be like a butter knife - not super sharp or anything, but sharp enough). Since the trem is pretty well used, I was able to restore the knife edges about 90%, without taking too much material off. Eventually, the bridge will need to be replaced because of this, but doing this bought it a good amount of time. Pic included is of the old edges - sorry, I spaced out and totally didn't get a pic of the freshly filed edges. After this, I applied a tiny bit of lubricant to the contact points for a smoother operation. Another common trick to use in a pinch is chapstick, but I used actual metal-contact lubricant.

The saddle inserts had grooves worn in them from years of string changes, and they were a mismatched set. A brand new set of Floyd Rose brand inserts took care of that.

As for the locking nut - I did order a brand new Floyd Rose brand nut, and I did get the correct width. However, I accidentally ordered a nut that was over 2mm higher than the original. This made the action unbearably high. Oops! The replacement nut I ordered was an R-3 size, and an R-8 size is the closest match to the original. The R-8 is not readily available outside of a special order (or the occasional lucky eBay score), so I made the executive decision to attempt to salvage the original nut.

Check the before and after - the string gouging in the original nut were pretty significant, but I was able to file them smooth. The locking blocks also had hefty grooving. The brand new locking nut on the left is the R-3 nut mentioned before, and ended up going into my parts bin. The new screws and blocks, however, were used for the job.

The original nut is a Jackson BH43, which is a discontinued part. I did manage to salvage the original Jackson nut by filing down the clamping surface enough to smooth it out, and to eliminate the string grooves that were cut into it over time. This allowed a good full pinch on the strings. The old locking blocks also had deep grooves cut in them. I simply replaced them and the screws with the brand new ones from the new R-3 nut.

My handy, small file set had some files that were perfect for the job.

Freshly-filed locking nut installed back into place.

... and now equipped with the brand new Floyd Rose-brand screws and locking blocks, taken from the new nut from before. Another advantage to this is these locking blocks have a bit more surface area than the old ones, which allows for better tension applied onto the strings.

Lastly, as explained before, the old trem springs were mismatched and presented uneven tensions. I actually ended up replacing the springs twice in this guitar. The first set of replacement springs were a fresh pack of Gotoh black-colored springs (not to be confused with the noise-dampening coated springs). I installed these at first, and they actually proved to be too heavy for my application. After the guitar was set up with these springs, the springs were almost completely compressed in the resting position. This actually caused issues with returning to correct pitch, because the springs simply couldn't compress any more. There wasn't much room for full movement in both directions.

I ended up ordering another set of springs, which are weaker in tension and non-coated. Since these springs have less tension, the springs actually have to be stretched further in order to balance out the bridge. This allowed much more room for articulation in both directions, and therefore allowing the bridge to return fully back to its proper, tuned position.

Despite the black springs being shorter, they have much more tension than the left ones. The left ones are the final product here.

But now - after completing all of this work, this guitar's tuning and Floyd Rose stability are restored!

No more pulling out of pitch, and no more issues returning to pitch. Locked and loaded. The last step will be to replace the trem itself, when the knife edges become worn out again. But as of now, it has some new life and should last me for a good while.