This post is a public service announcement. Last night, my Strat developed the dreaded "downstrum has stopped registering intermittently" problem that so many people seem to be having. Sometimes it worked fine, but other times (especially in fast-strumming rhythm sections) it would either not register some of the time, or double-strum. Upstrum (the real downstrum, for actual guitar players) still worked fine. It was bad enough that I was failing out of songs on which I can normally get four or five stars.
I read all the official forum posts in the RB tech forum (which propose a number of different remedies), and then decided to open up the case and have a look at the mechanism for myself. Unlike the GHIII guitar, you can open the back of the Strat without voiding your warranty (the Les Paul has a sticker over one of the screwholes that voids the warranty if you break it). So before RMAing it, why not have a look?
I'm glad that I did, because I was able to determine what the problem was, and I fixed it. My Strat downstrum now works 100%. I just went and played Maps on hard (my default calibration song), and scored 99%. Oh, and one other thing: if you hear a little rattling sound inside the Strat, that's normal. It's not a broken piece of innards kicking around in there, it's just the normal sound that the tilt sensor makes. I had the same thing, and thought something must have broken in there, but nothing was.
If your downstrum has stopped working, I'll bet you a dollar that you are experiencing exactly the same problem. Which means that you can fix it, too. It's not difficult, but it does require:
A very small (jeweller's) screwdriver. The screw that you will be adjusting is Phillips, but the slots are very thin and flat, so a flathead actually works better.
A regular phillips screwdriver. This is for the screws on the back of the guitar. They look small, but trust me, you'll want a good sized screwdriver to get the necessary torque. If you have a power screwdriver, that will reduice the amount of time required for this operation significantly (there are a lot of screws).
A set of tweezers. The type that comes in those little computer tool kits is ideal.
1. Remove all the screws from the back of the Strat with the Phillips screwdriver. There are quite a few, and if you are not using a power screwdriver, this will be the most time-consuming step of the process. Take note of where the screws go: they come in three different lengths. The two short ones go in the two holes at the top (where the guitar body is cut out), the four long ones go in the four holes on the back of the neck, and the medium size ones go in the rest of the holes. On some guitars, there may also be two additional screws on the front of the guitar, behind the pick guard. If the back will not come off after you have removed all of the rear screws, then remove the pick guard from the front (yes, even more screws!), and check to see if you have these.
- Carefully lift the back off. You are now looking at the back of the strummer mechanism. It looks like this:
It's a pretty simple mechanism. Basically, you have a microswitch that consists of two metal contacts sticking out of a square plastic housing ("tension screw housing") affixed to the body by a tiny screw ("tension screw"). A spacer between the contacts holds them apart in their resting state. When you strum, the plastic nub on the strum bar ("A") pushes the plastic nub affixed to the bottom contact and presses the contacts together. When you release, the contacts seperate. The plastic spacer between the contacts ensures that the bottom contact is under greater tension than the upper contact when the strum bar is pressed, making sure that when you release the strum bar, the bottom contact will snap away quickly. Note that there is a rubber pad affixed to the screw post that is above the top contact. This serves to dampen vibration when you press the strum bar (vibrating contacts can cause double-strumming). It is not, as some people on the official RB tech forums suggest, meant to push the top contact closer to the bottom one. In fact, ideally, the top contact should not even be touching the rubber pad in its resting state.
Here's what happens: the whole microswitch mechanism can rotate. The thing that prevents it from doing so is the tension screw that attaches the microswitch to the guitar body. If you are having problems getting downstrum to register consistently, chances are very good that the microswitch for downstrum has been rotated out of alignment slightly. It's possible that some of the guitars come with misaligned microswitches, or that the tension screw was not tightened sufficiently at the factory. It is also possible that even with a properly tightened screw, the microswitch gets pushed out of alignment over time through regular use.
Whatever the case, here is what a properly aligned microswitch SHOULD look like: The contacts should angle down towards the strum bar; they should not be parralel to it. The top contact will likely not be touching the rubber pad on the screwpost above it. The two plastic nubs (A and B) should be touching when the mechanism is in its rest state. If there is a small gap between them, then your microswitch has been knocked out of alignment.
The thing is, nub A is supposed to push on nub B when you strum, not hit it like a hammer. If there is a gap between the two nubs, then A is hitting B like a hammer when you strum. This will cause the lower contact to vibrate when you release the strum bar, which in turn will cause double-strums. Also, if the microswitch is rotated away from the strum bar, then you will have to press harder on the strum bar to make contact. This makes it much easier to miss notes, especially when you are strumming fast.
My microswitch was rotated away from the strum bar (I used the upstrum microswitch as a reference, since upstrum on my guitar was still working perfectly). The contacts were parallel to the strum bar, and there was a gap between plastic nubs A and B. The top contact was pressed against the rubber pad in its rest state. If your downstrum microswitch looks like this, then you have the same problem.
1. Using the very small jeweller's screwdriver, loosen (but don't remove) the tension screw that holds the microswitch in place. This will make the switch VERY loose. You'll be able to rotate/wiggle it freely.
With the tweezers in your left hand, grasp the tension screw housing. Rotate it counterclockwise (if you are fixing the downstrum microswitch) until the two plastic nubs are touching. Put some pressure on it--you want the plastic nubs to make good contact--but don't use so much pressure that the contacts are pressed together. Hold it in place.
With the jewellers screwdriver in your right hand (still holding the microswitch in position with the tweezers in your left), retighten the tension screw. Torque it down tightly (but not so much that you strip it out!).
That's it. Reassemble your guitar. It should now function properly.
It's not clear whether or not this problem will reoccur. If the misalignment was caused at the factory (perhaps the tension screw was never properly tightened, or perhaps the whole thing was just misaligned to begin with, when they tightened it), then this fix may be permanent. It could also be a design flaw, though--it is possible that normal play will slowly push the microswitch away from the strum bar over time, even if you have it tightened down properly. If that's the case, then a possible permanent fix would be to glue the thing in position with superglue. Then tighten the screw (to hold the microswitch in place while the glue cures), and give it plenty of time to cure before playing it again.
Personally, I'd rather avoid that sort of irreversible fix unless it's really necessary. If my strum bar gets flaky again, though...
There are some suggestions on the official Rock Band forums for how to fix the strummer. Many of them are wrong, and a few suggest doing things that you should probably avoid. Such as:
Filing down the "raised bits" of the contacts with a metal file. Don't do this. Those raised bits are an important part of the microswitch.
Placing tape (or some other sort of spacer) between the outside contact and that screw post that has the little rubber pad stuck to it. Some people claim to have had luck doing this, but I think it's a bad idea. All this does is bend the outer contact closer to the inner one. This may make it easier to register strums, but if you have space between your plastic nubs, then I suspect that it will do nothing to prevent double-strums, and it may even exacerbate the problem.
Edit: added info about extra screws on some models.