Yamaha DX1

The Mother of all FM operator synths.

Pete’s DX1 arrived dead. The repair, filmed in three parts, traces the fault to the switch-mode power supply. It starts with a careful passive examination of the SMPS (always treat mains voltage with respect), then follows the repair through until the DX1 powers up and plays again. With it working, all of Pete’s patches were recorded, so the sounds he programmed are preserved alongside the instrument, which is housed with the collection at the University of West London.

Here is the user manual…….if you dare!

Yamaha DX1 Owners ManualDownload

From the workbench

Restoration videos

A dead DX1 brought back to life, plus every one of Pete’s 128 patches.

Yamaha DX1 Repair Part 1

Chapters 21

  1. Intro – a dead DX1
  2. Lifting the lid & the power supply
  3. The battery & distribution board
  4. Blown fuse & checking the connectors
  5. Opening the power supply
  6. Removing the PSU board
  7. First look underneath
  8. Removing the bridge rectifier
  9. Shorted rectifier diodes
  10. Still a short on the DC side
  11. A blown resistor
  12. A shorted bypass cap
  13. Shorts cleared
  14. Checking Q1, Q2 & D2
  15. R3 & the triac
  16. Four-wire resistance checks
  17. Testing the MOSFETs
  18. The secondary side
  19. The cracked fuse
  20. Leaky caps on the secondary
  21. Schematic differences & next steps
Yamaha DX1 Repair Part 2

Chapters 10

  1. Intro – new rectifier & fuse
  2. Power-on with the bulb limiter
  3. Checking the rails
  4. Switching to 230V
  5. Working at 230V
  6. Removing the old glue
  7. Rail check & thermal camera
  8. Adjusting the 1.2V rail
  9. Reassembly
  10. Final voltage checks
Yamaha DX1 Repair Part 3

Chapters 5

  1. Refitting the power supply
  2. Final checks
  3. Power-on – it works!
  4. DX1 vs DX7 & load check
  5. Demo
128 DX1 patches from Pete Townshend’s collection
DX1 repair playlist on YouTube

More from the collection in the London College of Music playlist on the Really Nice Audio channel.