I can confirm moving J2 to J1 will convert this device from 100v to 240v capable.

Before :

AC input 249VAC
Stepdown output 104VAC
Transformer output 20.7VAC

After

AC Input 249VAC
Transformer output 22.3VAC

Thank you for the video!



Julien

This makes me think about the Meridian 519 since the came in both voltages…
Could it be simple as this
Sold my 110 volts one last year but kept the 230volts one as I am not a fan of voltage converters.

The Meridian 519 has a multitap transformer. I'm sure it can be modified to run on 220v

Can anyone confirm that a Japanese ADP-1 with the jumper in J2 can be safely run off USA 120v lines without a step down from 120v to 100v?

I certainly wouldn't like to confirm it, as the service manual linked up-thread doesn't cover the Japanese version.

However, the service manual does cover 120V, 230V, 240V, and 110-120/220-240V versions, and they all have the same transformer with 2 primary windings. And this Japanese version in the video has two windings too, so it's probably the same transformer.

So I think it's a fair guess that one winding can handle 100V-120V, and the other 220-240V and the output voltage should be within the tolerance of the device.

The circuit diagram suggests that the output should be 22.3V AC, and the gentleman who produced the video got this exact figure when feeding the 'hi voltage' winding with 249V, and got 20.7V when feeding the 'low voltage' winding with 104V. So it can clearly handle anything from 20.7-22.3V without any issues.

Doing the sums, I reckon you'd get (20.7 / 104 * 120) = 23.88V if you fed it with 120V, which is a little higher than the diagram suggests. If the diagram figure is a maximum, then that might not be good - if it's a 'midpoint' then clearly 1.6V below isn't an issue, so maybe 1.6V above isn't either?

So it could be safe enough at 120V... but it's not my device that I'm risking by saying that!