Can you chain several stepdown transformers?

[Xan]

So after checking my options, which weren't plentiful, I recently got one of those Kashimura converters for 220-240V -> 100V use and measuring it, found that what it really outputs is 115.xV with nothing and 113.xV with a PS1 hooked up to it (same whether it's on or not). Rather disappointing as that makes it basically ideal for US intended devices and not Japanese ones.

I figured I could go crazy and just get another one for 110-130V -> 100V, and that should be perfect, but is there any problem with doing that? I could also chance it and just use it as it is, would probably work for a while, but I do have a hunch it won't end well eventually. Found some varying info on what the tolerance for 100V is supposed to be but 110V is the highest it could be.

[Josh128]

Yes you can. US line to line voltage is usually ~240V or so and line to neutral is usually ~120V. The primary to secondary turns ratio is what matters, the voltage you get on the secondary is 100% dependent on what you input to the primary.

What is your actual source voltage and what is your target load voltage?

The safest bet would be to get a variac that you could feed with 115Vac and dial it down to exactly what you need. A lot more versatile for the money than another Kashimura unit like you already have.

https://www.amazon.com/Mophorn-Transfor ... 9hdGY&th=1

[Xan]

I think you are right about the Vevor variac. Could have just bought a local one designed for 230V input instead of importing the Kashimura converter. Both are made in China anyway. Only thing is some people do seem to suggest the Vevor units can be poorly built internally, bad soldering, hot glue, even a possible shock hazard with the metal case... well they are very cheap for a variac after all.

Normally I should be sending this Kashimura converter back to Japan. "Safe Japanese design" and 100V output is some bad false advertising if this thing outputs well over 110V. I guess at least this thread can serve as a good warning about those units though.

Now that I already have the Kashimura though, I guess getting another one would be similar enough in price to a Vevor and should surely get the voltage to a safe level below 110V. And I guess the one I now have should be perfect as-is if I ever wind up getting any US 120V hardware. Not sure yet what to do.

[Josh128]

I think you are right about the Vevor variac. Could have just bought a local one designed for 230V input instead of importing the Kashimura converter. Both are made in China anyway. Only thing is some people do seem to suggest the Vevor units can be poorly built internally, bad soldering, hot glue, even a possible shock hazard with the metal case... well they are very cheap for a variac after all.

Normally I should be sending this Kashimura converter back to Japan. "Safe Japanese design" and 100V output is some bad false advertising if this thing outputs well over 110V. I guess at least this thread can serve as a good warning about those units though.

Now that I already have the Kashimura though, I guess getting another one would be similar enough in price to a Vevor and should surely get the voltage to a safe level below 110V. And I guess the one I now have should be perfect as-is if I ever wind up getting any US 120V hardware. Not sure yet what to do.

Variacs are useful for a lot of things, including troubleshooting CRT issues. I even used mine to modulate a heater I hooked up for some baby chicks I hatched when they were tiny, lol. As far as Vevor, its a Chinese brand that literally makes almost everything under the sun, and while Im sure ymmv, I've had very good luck with every single thing Ive purchased from them so far, the most industrial was a ~220V .75HP motor to replace a burnt one on my dads relatively new large tank Ingersol Rand air compressor. It was half the price of the "US Motors" motor that it replaced.

My personal variac is not a Vevor, but a similarly priced 2000VA red Chinese made no-name brand from Ebay. Looks identical other than the paint, probably made in the same factory. Its heavy and hulking, weighs around 10 lbs. I paid $69 USD for it and its worked great so far.

[Xan]

Found this old assemblergames thread where several people said switching PSUs for 100V may be fine up to 125V: https://assemblergames.org/viewtopic.php?t=330

5th gen consoles like PS1 all use switching PSUs, right? Maybe I'm being overly cautious and it would be alright at 113/115V. Just can't use any 100V linear power adapters on it as they will get too hot and might overshoot the output voltage as well.

So perhaps I could use it like this for a while and still get the second Kashimura for peace of mind. Though I've read that using two stepdowns in series will double the losses and could increase the heat on the first transformer, so it's not a perfect solution either.

[leonk]

Electronics of that era are rated for +/- 20%. Feeding 115V to a 100V retro console is perfectly safe. I plug all my Japanese computers and even arcade machine (with 100V monitor) to the electrical outlets here and they run fine at 115V.

A lot of these devices still use linear transformers and voltage regulators. The most common regulator (7805) accepts input voltage of 7-25V!

[Xan]

I doubt +20% at least for 220V rated devices. For reference, my mains voltage is around 245V and I've stopped hooking up anything that says 220V only (not 220~230V) after some experiences with magic smoke.

[Josh128]

Found this old assemblergames thread where several people said switching PSUs for 100V may be fine up to 125V: https://assemblergames.org/viewtopic.php?t=330

5th gen consoles like PS1 all use switching PSUs, right? Maybe I'm being overly cautious and it would be alright at 113/115V. Just can't use any 100V linear power adapters on it as they will get too hot and might overshoot the output voltage as well.

So perhaps I could use it like this for a while and still get the second Kashimura for peace of mind. Though I've read that using two stepdowns in series will double the losses and could increase the heat on the first transformer, so it's not a perfect solution either.

Transformers have inherent efficiency losses in the form of heat, its generally a varying (but very small) percentage of the power drawn by your load. A transformer feeding a second transformer would have the same power dissipation, but because you have two transformers, its just double the power dissipation overall . Nothing to worry about, most transformers are >90% efficient. It'd be a dollar or two more on your lighting bill, lol.

If you really want to dial in the voltage, just get a single variac, and sell the adapter you bought. You cant go wrong. Where are you, UK? Look at this:

https://www.ebay.co.uk/itm/116976215364 ... 59EALw_wcB

[Xan]

I've used it for a bit like this now and it doesn't appear that my SCPH-5500 is getting any warmer than an equivalent PAL unit. My Japanese Model 1 Saturn is getting quite warm however, particularily in the PSU area. I'm much less familiar with it and it may just be how the console runs though.

By the way, I've noticed a huge discrepancy in rating for the 100V Saturn consoles vs. the PAL 220-240V ones - 12W and 20W, and apparently even 25W for the 120V one. There is no such difference with the PS1, which is kind of interesting.

Edit: I realized the Saturn PSU actually has a voltage range printed on it, which is 85VAC-132VAC. On mine this is even visible without taking the unit apart.

[Guspaz]

In the service manual for the SCPH-5500 through SCPH-5503, we see the following power ratings:

SCPH-5500
100 V AC, 50/60 Hz
9W

SCPH-5501
120 V AC, 60 Hz
17W

SCPH-5502
220-240 V AC, 50 Hz
9W

SCPH-5503
110-240 V AC, 50/60 Hz
11W

It's not clear to me why there is almost a 2:1 range in power consumption between the different models. Or why the 5501 is a hundred grams heavier.

[Xan]

Maybe there is some US regulation according to which companies had to give a peak power draw (inrush current), and the different region variants would perform the same in real life.

To top it off, it's not like there is just a single PSU per model. There are a couple ones by different manufacturers, so maybe the one they had on hand for the 5501 was a bit heavier due to component differences. The Nichicon PSU has a standing regulator on a heatsink that the others don't, for instance.