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Using 100v Japanese Electronics in North America

Joined
May 15, 2021
Messages
6
Hello all I recently got an 80s sequencer intended for use in Japan where they use 100v
I am trying to figure out if it is safe to use it here in North America without a step down converter and cant find a definitive answer googling
I was hoping someone with more knowledge than me could help me understand

Here is a photo of the PSU:
cUJGhOP.jpg
 
It's really hard to say. It comes down to if they built the PSU to a 100v spec and didn't factor voltages 10-20v higher because it would require slightly more expensive components. I have seen and do own Japanese electronics myself that are rated for 100V and run fine on 120 but there's no real way to identify weather a PSU was under-specced or specced to max beyond what the input voltage of the bridge rectifier can handle.
 
You'll be fine--I've run 100V rated Japanese monitors and computers on 120V with no problems at all. Your PSU is a switch-mode one; they tend to be more tolerant of input voltage variations than the old linear stuff.
 
You'll be fine--I've run 100V rated Japanese monitors and computers on 120V with no problems at all. Your PSU is a switch-mode one; they tend to be more tolerant of input voltage variations than the old linear stuff.

+1
that's definitely a SMPS design (no big iron transformers, common-mode chokes, small ferrite switching transformer). So it will likely work fine at 120V, drawing less current. Just check the rating of the main capacitor. I must be higher than 120 x 1.41 volts.

Frank IZ8DWF
 
+1
that's definitely a SMPS design (no big iron transformers, common-mode chokes, small ferrite switching transformer). So it will likely work fine at 120V, drawing less current. Just check the rating of the main capacitor. I must be higher than 120 x 1.41 volts.

Frank IZ8DWF

The capacitor says 200v 100uf. The mosfet beside it is NEC C3570 K 65 (http://www.datasheet-pdf.com/PDF/C3570-Datasheet-NEC-861446 ?) . So it should be fine?


Are you sure that's not a worldwide-voltage power supply? It has a 250-volt fuse in it.

Since the capacitor is 200v I'm assuming it wouldn't work in Europe? But why else would there be a 250v fuse
 
AGC glass or ceramic fuses commonly come in two varieties - low voltage; e.g. 32 volt DC, used to be used on a lot of automotive circuits before the "blade" type fuses took over, and 250 volt, intended for line-powered equipment. There are further sub-categories, such as slow-blow, fast-blow, etc. So an AC glass line fuse will always be a 250 volt rating. That voltage is important in a practical sense--you don't want the fuse to arc when it blows; similarly, you don't want it to explode.

You'll see a lot of manufacturers label their fuses 125/250 volt. They're the same as 250 volt. Rule of thumb for a fuse is that it's safe to use a higher-voltage rated fuse in a lower-voltage application, but not the reverse. So a 32V 5A fuse could be replaced by a 250V 5A one and still afford protection, though that could mean that it's less tolerant of currents exceeding the fuse rating.
 
IIRC, Japanese power is 50 Hz instead of 60 Hz so keep that in mind as well.
 
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