SY-99 Teardown

Well, I have an SY-99. And like any old electronic device, it always needs some kind of repair. During one such repair (out of the three it needs, total), I took some pictures. They've been kind of lying around since, but I figured I'd upload them with some commentary, because it's an interesting build.

For those who don't know, the Yamaha SY-99 is the most complicated synthesizer Yamaha ever made. If you don't believe me, just let me hit you with the several hundred page user manual and the MIDI format addendum. Heck, even the on-screen user interface is several hundred 'pages', using the manufacturer's own terminology. It uses the very same AWM2 sample-based synthesizer engine Yamaha is still using today (though they don't really advertise it anymore - it's not like there's any real difference between it and any other PCM sound system), combined with an AFM synthesis engine. AFM is Yamaha speak for FM synthesis with eight usable operators instead of the more standard two, four, or six. These synthesis engines are augmented by two very high quality effects DSP, which are capable of a number of different effects including the then-new aural exciter.

This synthesizer is actually the big brother to the earlier SY-77, but there are a number of enhancements that are, for the most part, minor. However, there is one feature that is completely unique to the SY-99 which is major for a number of reasons. The keyboard is capable of what Yamaha has dubbed RCM, or Realtime Convolution Modulation, and basically what it does is it modulates the output of one voice from the AWM2 section with the AFM section. This is pretty major; it basically means that the SY-99 is not entirely limited to the handful of sine-based waveforms previously available in other FM synths. But as this is the last keyboard Yamaha would produce with an FM synthesizer, it also means that it's the only synthesizer of it's kind. It's rather strange, because it means that this several decades old piece of hardware is still Yamaha's most advanced synthesizer, in a way.

But when you get down to it, being more advanced just means more complicated; despite the surprisingly intuitive software-based controls, getting any real sound out of it can be difficult; programming the rich and vibrant sounds that this keyboard is known for can take hours out of the day. There are voice presets, but not many - definitely not covering the full GM Spectrum. But it's a professional tool through and through; every single thing about it is high quality, from the heavy full steel body, to the full-weighted keyboard, to the extremely clean and just perfect audio output.

The SY-99 was not completely lost to history; Yamaha's later Motif keyboard workstations (which, like the 99 was, is their high-market product) are very clearly modeled after the SY-99, and even some of the synth sounds are very similar. It wouldn't surprise me if it had a new iteration of the same effects processor.

But enough tech talk; let's take a look at what's inside.

This is just from the first step; the rear cover was just removed and you are just seeing the very first layer of circuit boards. And yes, I mean the first layer, as in there are multiple - usually somewhere between two to four, since there are no boards that stretch the whole way across.

The transformer on this is HUGE. And I'm actually pretty glad, since this is technically a european version and I have no idea if the converter I have is any good or not. The power circuitry is very important in this since it is a professional audio product; if it generates too much noise or radio interference, it will affect the quality of the audio.

This is just a quick picture of one of the two main system boards. Nothing too incredible here; most of the chips are made by Yamaha themselves, or are at least marked specificially by them. It does have a mark of it's times, though; if you look at those bar-shaped components at the bottom, you may notice that they are dreaded ZIP chips. I am so glad nobody uses that package anymore.

The second system board. Also not much of note.

The keys in music keyboards are always pretty interesting as well. I took this picture to show off the leaf switches they use on here; there are actually two of them per key, and the time between their activations is what determines the velocity of the note. Not pictured is the pressure-sensitive strip on the other side of the keyboard used for aftertouch.

The only other thing I wanted to show was how much free wiring there is on this build. This is just one small segment that I took a picture of just to make sure I was able to wire it back together correctly. I can't imagine how many bad assemblies they must have built when assembling these new. Seriously, there are about ten wiring harnesses per board on average, and many boards use those stiff ribbon cable (I assume that this was before plastic printed circuit cables became popular, but as far as long-term repairability, I consider that a plus)

Really, there's a lot more to this keyboard. The main reason why I didn't take more pictures is simply because I got tired of doing it halfway. It literally took me several days to disassemble it to get to the problem I was repairing (the buttons on the front weren't working. I replaced something like 50 of them).The only thing I regret not taking a picture of was all the shielding. There were more plate steel shielding pieces built into the thing, and they also used a plastic-reinforced aluminum foil to surround each board.

But the best thing about opening up this synthesizer is to learn just how much effort went into this thing. The engineers really didn't spare any expenses and made sure that they made the best instrument they possibly could, and that shows throughout every design decision they made. Frankly, I am so impressed by the quality, I think that $30,000 in 1991 money seems like a value. And it was worth it. I have not heard anything that sounds better than this synthesizer. And that's saying something.