This hopefully will be the definitive guide to solving the dreaded Oberheim Matrix 1000 vibrating PSU issue. I like many others experienced the same issue, and it occurs when the transformer itself makes loud hum noise due to magnetostriction in the core material. Since the circuit is all linear, there are peak haversines of current flowing through the transformer to charge capacitors every cycle, and these peaks can be high enough to get the core laminations moving (if they are not staked well and varnished well) Its also an issue that can (and does) increase over time, as is the case with the M-1000 PSU vibrating like crazy. There is no easy way to quiet that down if it’s happening and a metal clamp (like the often suggested TX81Z fix) doesn’t do much. The only solution is to remove and replace but finding a linear PSU that will fit, is near impossible. The only real option is a switching power supply and one that has multiple voltages. In this case the M-1000 requires a quad switching power supply that can deliver 5V, 12V, -5V, -12, and a bypass of the onboard regulators. I had this work done by a synth tech but even someone with some limited skill could do it (BUT DO SO AT YOUR OWN RISK!!) Still it's pretty easy and shouldn’t cost much to do by any decent electronic technician. Anyway here are the steps and some photos. I got mine done and its glorious. This classic synth is worth the effort!!
Step 1: Use a volt meter and carefully measure the voltage on each regulator listed and on the photos (Make note of each, You will be looking for +5, -5, -12, +12. The attached schematic is very hard to read but you can reference that as well.)
Step 2: Completely remove old power supply and associated hardware
Step 3: Remove 5 regulators (shown in schematic and photos)
- 7805 (x2)
- 7905
- 7812
- 7912
Step 4: Install new PSU (Mean Well PSU RQ-50 - see attached pdf) Cost about $20-30 USD
RQ-50B: 45.5W AC/DC Enclosed Switching Power Supply: Mean Well
Step 5: Use one of the old holes to mount the new PSU our drill your own
Step 6: Apply some adhesive rubber strips on top (to keep case from rubbing)
Step 7: Run wires to each of the matching power points on the board you measured before (Note that you have to run a double wire off the PSU +5v terminal for the two 7805s which each require +5v)
Step 8: You have to run a common ground wire on U7 going back to the PSU (see on photo)
Step 9: Test
Good luck!