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YAMAHA MODX7+ won't power on

Hi everyone,

I have a brand-new Yamaha MODX7+ that won’t power on at all — no screen, no LEDs, and no response from the power button.
I purchased the unit from Japan (PA-150B adapter included). It arrived in pristine condition, unused, in original packaging with all protective foam.

Here’s what I’ve done:

Measured the adapter output with a multimeter: stable 12.15V

Tried different outlets and high-quality plug adapters (I’m in Europe, 220V)

Removed all external connections: no audio cables, no sustain pedal, no USB

Held the power button for 5 seconds — no reaction

The DC jack is firm, with no wobble

I gently twisted the DC plug during power attempts — no effect

At this point, I suspect either:

  1. A blown internal fuse
  2. A failed power regulation circuit on the mainboard or power board
  3. A disconnection somewhere in the internal chain

Before I open the case, I’d appreciate any advice:

Where exactly is the fuse located?

Is it a T1.25A 250V slow-blow (5x20mm)?

Has anyone here successfully replaced it?

Any other suggestions?

Thanks a lot in advance! 🙏
I don’t want to ship it back to Japan.
 

Comments
SzBálint
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Octic
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Hi dear SzBálint,

I just wanted to say a huge thank you for sending me the MODX7+ manual and pointing me in the right direction.

Thanks to you, I finally realized my mistake — and honestly, I feel pretty embarrassed that I didn’t notice the Standby/On switch on the back panel… 

I spent so much time checking the adapter, measuring voltage with a multimeter, thinking the fuse was blown, digging through schematics, looking for repair shops — and all along, the issue was just one switch I didn’t flip.

The manual was right there from the start, but I didn’t read it carefully enough. Lesson learned the hard way.

Once again, thank you so much for your help, your patience, and for saving me a ton of time, stress, and possibly even repair costs.

With sincere appreciation,
Octic

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SzBálint
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hello:

OK

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