Hi I recently picked up a Yamaha DX7 MK1 from 1985 for about $265. It's really dirty and of course the clock battery was dead. It also has problems with the headphone output being scratchy and popping, and the volume slider also acting up.
I decided to tackle the battery issue first. I bought this holder from Analog Classics:
https://analogclassics.com/product/batt ... d-fd-dx21/
I soldered the wires correctly to where the battery is supposed to go, as seen in this picture:
![Image]()
However, I was still getting issues with the synth freezing on bootup, or yelling "CHANGE BATTERY!". I've checked using a multimeter and I'm getting +3.2 volts between those wires. Not -3.2V, +3.2V.
So I recapped the power supply board, using exact replacements made by Panasonic from DigiKey. Using a multimeter I'm still getting my +15, -15, and +5 from the PSU, so I did recap it correctly.
I also replaced some capacitors on the main board, again using *exact* Panasonic replacements from DigiKey. The mainboard is not fully recapped yet but the PSU is fully recapped. I also replaced the tantalum capacitor on the mainboard that keeps the CMOS VCC stable.
This is a video I made after replacing those capacitors:
As you can see it is still acting up and sometimes it puts junk on the screen, sometimes it doesn't, sometimes it just spazzes out, but most of the time it just yells "MEMORY PROTECT, CHANGE BATTERY!". None of the buttons work at all, and I've made sure those plugs are all in there correctly. I've tried holding Function and 16+32 at the same time, nothing.
I decided to tackle the battery issue first. I bought this holder from Analog Classics:
https://analogclassics.com/product/batt ... d-fd-dx21/
I soldered the wires correctly to where the battery is supposed to go, as seen in this picture:
However, I was still getting issues with the synth freezing on bootup, or yelling "CHANGE BATTERY!". I've checked using a multimeter and I'm getting +3.2 volts between those wires. Not -3.2V, +3.2V.
So I recapped the power supply board, using exact replacements made by Panasonic from DigiKey. Using a multimeter I'm still getting my +15, -15, and +5 from the PSU, so I did recap it correctly.
I also replaced some capacitors on the main board, again using *exact* Panasonic replacements from DigiKey. The mainboard is not fully recapped yet but the PSU is fully recapped. I also replaced the tantalum capacitor on the mainboard that keeps the CMOS VCC stable.
This is a video I made after replacing those capacitors:
As you can see it is still acting up and sometimes it puts junk on the screen, sometimes it doesn't, sometimes it just spazzes out, but most of the time it just yells "MEMORY PROTECT, CHANGE BATTERY!". None of the buttons work at all, and I've made sure those plugs are all in there correctly. I've tried holding Function and 16+32 at the same time, nothing.
Statistics: Posted by KylesDigitalLab — Sat May 18, 2024 8:46 pm