Japanese Saturn For Use In USA

On the units I have here, the PSU markings are as follows:

Yamaha model 35M07
Ac input: 100V-120V 0.4A 50/60Hz

Fujitsu Denki KS350-1401-H031/04 (x2)
Ac input: 85V-132V 0.4A 50/60Hz

Voltek Model S-7218 34507-8
Input: AC100-120V 50/60Hz 0.35A

Yamaha model 35M10J
Not specified on PCB

All of these are Japanese market units with "100V 50/60Hz" marked on the rating label.

The last one doesn't have a voltage rating at all, but it all looks plausible:

The tolerance for US mains is +/-5%, so the high line condition is 126VRMS - about 178V peak.

Filter cap is 100uF @ 200V
Withstand voltage on the VDR is 140VRMS
Rectifer (S1WB60) is rated at 600V VRRM (should be at least twice the peak line voltage)
Switching transistor is a 2SC4953 - rated at 400V Vce (MAX)

In fact, the only thing I can see that's out of spec is the RFI filter cap, which is rated at 125V - so 1V below the US high line condition, but I really can't see this causing any problems in the real world.

There is a vague possibility that the transformer might saturate because the higher line voltage would result in narrower pulses with a higher peak current, but I honestly can't imagine Yamaha designing something that marginal.

 

x

 

Wow I didn't expect so many responses! Thank you all.

@TriMesh I love reading your Playstation Hardware Posts! You seem very knowledgeable!

@ASSEMbler I'd totally be willing to spend the $20! Any recommendations?

 

Yeah, it's normally right next to the power input socket - it's half of the EMI filter (the common-mode choke is the other half) - US market stuff tends to use 250V rated caps in that position, along with 250V rated fuses.

I also just found another variant:

Voltek Model: S-7208
No voltage markings on PCB

Line filter cap: 125VAC (2B)
Rectifier filter cap: 120uF, 200VDC
VDR: 220 varistor voltage (140V withstand)
Rectifier: 600V (DF06)
Switching transistor: Uses a TOP102-YAI TOPswitchIC - maxium drain voltage is rated at 350VDC, and all of the application circuits specify a 85-132V operating range.

So this is basically the same deal as the later Yamaha one - everything except the input filter cap is rated for 120V operation.

 

You can get a nissyo my-pet.

http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=nissyo&_sop=15

 

Anyone have an experience wit the VCT VT-500J? (http://www.amazon.com/dp/B000PC4JL4/) I don't mind spending a little more to buy from Amazon as I'm a prime member. They also have a slightly smaller 200w (which should be more than enough, 100v * .4amp = 40 watt device right?) the VT-200J http://www.amazon.com/dp/B004S2COIC/

 

Simple explanation:
A switching power supply works transforming AC to DC, storing it ("energy") on a capacitor and getting small slices of this "energy" in a way that, integrating the curve, it will result in a lower DC voltage on the output. So, reasonable variations on voltage input (up to 25-30%) will do no harm. The main capacitor will have enough energy to supply the switcher).

Complete explanation:
Switching power supplies works by rectifying AC to DC on input, storing it into an input capacitor (or two, depending on topology) and getting bits of this energy to excite the transformer and having something on the output. This capacitor is rated usually to 350-400Volts, so anything you put on that from 0 to (max voltage) is feasible. Of course, the switching power supply has a minimum primary voltage to work. Usually around 85-90 volts. But anything from 90 to 180 volts on the input will work without stressing the primary side of the power supply. Since the switching power supply takes "slices" of the energy stored on the capacitor, varying the switching time of the switching transistor(s), it doesn't mind much how much voltage is applied on it, IF the PWM controller can strech the "on" pulse enough to have enough energy on the output.

Maybe the explanation is too complicated (or too simplistic) for people who doesn't know how a switching power supply works. But it is something on these molds. 20-30% of more or less voltage on the input will do no harm.

If someone here is in doubt, I can create a video using a variac to change input continuously from 90 to 150 volts and show there is no variation (nor harm) on the output voltage of the PSU

Sorry for the delay on the reply!

 

Okay then, thanks for the lengthy explanation! The device I was talking about is an old Taito cocktail table arcade machine. It has a switch inside that lets you choose between 90V and 100V, so I guess my new question is: are there any differences between the two if I'm converting the voltage to 240V using a step-up transformer?

 

I believe I didn't understand it correctly, DeChief. You're inputting 240V into a 100V power supply?

 

I have an arcade machine that normally requires 100V, but can be switched to requiring 90V instead. I live in Japan, so the power coming out of the wall is 120V, but when I move back to Australia (where the power is 240V) I'm going to need a transformer.

So my question was: is there a difference between the 90V and 100V settings on the arcade machine that could cause damage if I'm using a 240V to 120V transformer?

 

No, if you're in Japan then the voltage coming out of the wall should be 100V +/- 5% at either 50 or 60Hz depending on where you are in the country. The 90V setting is intended for areas that have bad wiring.

So put the unit on 100V and get a 240V to 100V stepdown. Depending on where you live it might be worth checking the line voltage with a meter before turning anything on - but this is mostly an issue if you are out of town (some rural areas in NSW have line voltage that goes over 260V at times of light loading, for example - and according to the spec they could sit at 264V all day and still be "OK").

 

Fast answer: No.

Better answer: If you're going to buy a step-down transformer, why don't you buy a 240 to 100v step down transformer?

 

Well that's what I'm saying, does it really matter? I only want to have to buy one transformer because they're so expensive, and I also have US and Japanese consoles that run on 120V, so would a 240V to 100V step-down be acceptable for them too?

 

This is a question it's almost impossible to give a definitive answer to because it depends on the unit. Generally speaking, it will work - if you connect a (nominal 100V) Japanese console to 120V you are subjecting it to a 20% overvoltage, and most equipment can tolerate that without damage. The other way around (120V US equipment on a Japanese 100V supply), it's getting a 17% undervoltage - this is very unlikely to damage anything, but some sensitive equipment might not work correctly.

If you want to get a single transformer, then see if you can source a 240V->110V unit - that will be 10% overvoltage for the Japanese stuff, and about 8.5% low for the US equipment, and that should be well within the tolerances of even the most marginal system.

Personally, the only Japanese PSU I've seen that gave serious problems on US mains was the one for the original NeoGeo CD - I don't know if it was the increased line voltage, bigger spikes or something else, but one of my friends imported a batch of these things to the US, and within a year the PSU failure rate was close to 100%.

 

I'd go to the 110V transformer. Although I doubt any videogame would be damaged by this little over/undervoltage.

Many of my videogames (lots of Saturns, etc) and computers (MSX Turbo-R, etc) are 100V units. And I use them on 127V for years