There are rubber stoppers under each key to ensure that they stop the contact wires in the right place and the keys play with a nice feel. All you need to do is clean any crud off the wires with an eraser or light sand paper without bending them out of place. It is simply a long bus wire that runs the length of the keyboard with small wires for each key that make contact to the bus wire when the key is pressed. The J wire keyboard setup is quite easy to fix if you treat it delicately. A few took 2 or 3 times through the process, but by the end they were all smoothly working and good as new. Just a short spray and then I spent some time working the switches and pots through their full range of motion. The switches and pots were easily fixed by using the Deoxit F5 Faderlube. The audio buzz was fixed by re-soldering a connection to the audio output jack. I simply bent the metal fuse connectors for a more solid connection, sprayed them with D5 to remove corrosion and bent the latches out that hold the fuse housing more firmly in place. ( a red plastic fuse case on the rear of the unit by the power cord.) It was a quick fix. After that I turned my attention to the intermittent power failure problem. I started with using the Deoxit D5 on all of the connections to see what was dirty and corroded and what actually needed repair. A few nice touches that remind you that you are performing surgery on a lovingly designed artistic instrument, not just another mass produced piece of electronics. There is an elaborate Buddha, some ancient / alien looking symbols and even a cluster of mushrooms and flowers all imprinted in raised silver. (I always wait several hours before powering up a circuit board after cleaning it with any solution) The circuit board itself had a surprising amount of artistic customization. I started by cleaning the board with a small amount of alcohol on paper towel and q-tips. Now it was time to clean up circuit board, repair loose connections and recondition the pots and switches. The wood sides were in great shape and only needed some furniture polish. The outside shell needed some light soap and water, and a bit of all purpose orange cleaner. Most of the basic internal cleaning was done with air bursts and a small amount of 90% isopropanol alcohol on a rag. I half expected to find a dead rat wedged in there. Step number one was to completely break down the Pro One and clean every square inch! There are plenty of tutorials out there on how to take apart a Pro One, so I will not go through every screw here. Deoxit F5 is a fader lube and it works wonders on sticky / frozen / scratchy faders, pots and switches. Many of the problems with this unit were simply fixed by cleaning the connections with D5. Deoxit D5 is a contact cleaner and an amazing tool for cleaning and caring for vintage electronics. 90% isopropanol alcohol is usually a good cleaning choice for electronics since it evaporates so quickly. I hunted for a serial number below 8500 to ensure that I was dealing with the J-wire keyboard setup, but above 1500 to avoid having a unit with the main power supply mounted to the circuit board which reduces durability.įirst let's talk cleaners and solutions. The Pro One's with serial numbers under 8500 are equip with the stable and easy to repair J-wire style keyboard, while serial numbers above 8500 have the more troublesome and difficult to repair membrane keyboard. Pro One buying 101 starts with serial numbers. There were a few other problems, but I don't remember them now. The housing was dirty, the pots were scratchy, the unit only powered up intermittently, the audio was buzzy, the keyboard keys were uneven and several were non-functioning, at times the unit only produced noise in the drone mode and the CV pitch and note scale were off causing out of pitch notes no matter how carefully you tuned the oscillators. Sequential Circuits Pro One (Repair and Reconditioning)īuying a mint Pro One was not an option at today's high prices, but I found a good deal on eBay and was convinced that I could recondition it myself.
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