Diagnosing and attempting to fix a Yamaha DX100 – Part 4

I decided to have one more look at the data pins, largely inspired by this oscilloscope trace from part 3. I figured if the address and select pins were working (yellow, cyan and purple) what could I do to try to work out what is driving the data pins (darker blue) wobbly... And no, after … Continue reading Diagnosing and attempting to fix a Yamaha DX100 – Part 4 →

Diagnosing and attempting to fix a Yamaha DX100 – Part 3

At the end of part 1, I've established that the basics all seem ok (PCB, interconnections, power) and that basic digital logic stuff is happening. In part 2 I checked the ROM, reflowed a number of the solder joints, and started to look at the connectors between the main PCB and the LCD, but still with … Continue reading Diagnosing and attempting to fix a Yamaha DX100 – Part 3 →

Diagnosing and attempting to fix a Yamaha DX100 – Part 2

At the end of part 1, I've established that the basics all seem ok (PCB, interconnections, power) and that basic digital logic stuff is happening. I rounded off my write-up with the following ideas for what to investigate next: Get some proper triggering from the chip enables to check for valid data signals. Check out … Continue reading Diagnosing and attempting to fix a Yamaha DX100 – Part 2 →

Diagnosing and attempting to fix a Yamaha DX100 – Part 1

I was very lucky to be offered a non-working Yamaha DX100 from Simon Walters. On arrival I can see it attempts to boot but apart from the odd character on the screen, I wasn't really getting anything useful happening. My thinking here is that as it is a pretty nice synth with most of its functionality … Continue reading Diagnosing and attempting to fix a Yamaha DX100 – Part 1 →