Great news everyone – D’Naab 136, the guy who designed the replacement for the Juno 106 chips, has just let me know he released a version two of his creation, which is smaller, better, and helps to keep your dog happy. Or your snake. And it’s still 40 euros. Awesome!
I bought a bunch of original chips off eBay last year, and one of them already died, plus there is one more that’s getting really noisy. Learn from my stupidity, and get the replacement chips.
Now, I’ve received quite a few comments to my original post with people asking how to fix their Juno. Most of those had to do with the same old VCF/VCA chips dying. I have put together a list of possible symptoms of a dead chip.
- A note is stuck. Also sticky note, or hanging note. Play 6 notes at a time, and if one of them never shuts up, one of the chips is dead. What happens is that when you normally play, all the notes you strike always sound. The job of the VCA chip is to bring the volume down depending on how you set your envelope (that’s how you hear the note fade away if you increase the Release of the envelope, even though you are not touching the key anymore). A bad one, however, will keep playing as if the Release is set to infinity.
- A note is too loud. This could be a few things. One is that one of the chips is actually louder, and that could just be an adjustment problem. More often though, one note plays with the filter fully open, whereas all the other ones don’t (“I have a soft pad sound with the low-pass filter set quite low, but one note always plays an open raw saw”). That’s the sign of the filter not closing properly. Bad chip.
- A note is noisy. Or sounds garbled like an encrypted transmission from Martians. Sounds as if you were to modulate the filter with a white or pink noise. Signs of the chip going crazy. I’ve sampled that sound, and you should too – it sounds pretty darn cool. It’s actually a good reason to have your Juno broken.
A way to test for all of these problems is to start the Juno up in test mode. Turn it off, press and hold the Transpose button, and start it up again. You should see two dashes on the LCD, with the second one being lower than the first. Now, press the Poly 1 and Poly 2 buttons at the same time, and start hitting the same note on the keyboard. Every time you do, you’ll see a number on the LCD indicating which chip the note is playing through (1 through 6). Take note of the number of the chip which acts up, you’ll need it when you open up the Juno later.