Yamaha DX7 No Sound

Hi everyone, hope somebody can help me out! I’ve been using my DX7 for the past couple of decades as a midi controller (I’ve had since 1985 and can’t bring myself to replace it with something lighter with touch sensitive keys!). All the internal and cartridge sounds are displayed as they should but aside from the Ref’ Whistle (INT29) and the bell of Train (INT31), none of them produce the sounds they should. If I turn the gain up on my mixing desk I hear a variety of what sound like electronic pulses. I don’t know how long ago it started doing this as I’ve only just noticed! From what I can see, all other functions look like they’re working ok. I’ve tried a factory reset to no avail!


Sounds like the D/A converter has gone, but it may be 741 or 1458 down the line on the filter section.
Regardless, Its time for a complete service and Electrolytic capacitor replacement. All Yamaha DX electrolytic caps are time expired.

What kills the D/A converter is an out of range voltage from a leaky capacitor. If your power supply hasn’t had its capacitors replaced, plan on that and any on the motherboard too. 741 and 1458 op amps are plentiful, but the D/A converter is unobtanium, unless Syntaur has one in stock. If you feel its worth saving take it to a proper tech for servicing, your local music store should know of someone.

If you feel its NOT worth fixing, some of the other motherboard chips are unobtanium and can only be gotten by salvaging other DX units. Contact Syntaur via email to see if they need parts off your unit.

Another user was asking for a DX7 power supply transformer earlier in the year, so don’t just chuck it.