DX7 Power Cycling?

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DX7 Power Cycling?

Post by jgeroux2 » Tue Aug 11, 2020 8:22 pm

Hi all.

I have a DX7 that will start power cycling once warm. No sound (only sine wave) and won't play sounds from cartridge or internal memory. Will shut off and turn back on again even though power button has not been touched.

Any ideas where to start looking?


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Re: DX7 Power Cycling?

Post by meatballfulton » Tue Aug 11, 2020 11:03 pm

First, I would get my hands on the schematics and if possible the service manual. Then I'd open up the DX to get access to the power supply and meter the various supply voltages.

Do NOT do this unless you are familiar with the dangers of poking around circuitry while the AC power is on, you could damage the unit or electrocute yourself.

If you have a heat gun available, use it to slowly warm up the supply and watch what happens to the voltages. If you don't have a gun, just leave the DX powered up and keep an eye on the voltages.

Again, be careful! If you have no electronics repair experience, take it to someone who is qualified.
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Re: DX7 Power Cycling?

Post by Weirdofromouterspace » Wed Aug 12, 2020 1:09 pm


What he said, plus:

Upon opening the synth (unplug it from the mains supply before doing so) and before re-connecting it to the mains supply and measuring voltages, check the PSU visually. Especially for damaged/leaking/bulging electrolytic caps and obvious broken solder joints.
Don't forget to TURN ON THE SYNTHESIZER. Often this is the reason why you get no sound out of it. - ARP 2600 manual, 1971

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Re: DX7 Power Cycling?

Post by SciNote » Wed Aug 12, 2020 5:50 pm

What they said...

And, as an extra word of caution, remember that capacitors can hold a potentially lethal charge even after the unit is unplugged from the mains (household AC power outlet), and they can hold this charge for a significant amount of time after the unit has been unplugged. So, as mentioned above, do not attempt any of this if you are not familiar with electronic circuitry and the dangers of working on it, whether the unit is plugged into the mains power outlet or not.

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