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Power supply conversion from 100V to 230V.

Posted: Sat Dec 20, 2014 7:54 pm
by Yekuku
I have a Japanese CS30 that works on 100V and I would like to modify the PSU so that it works on 230V. (Europe)
I thought that a simple transformer + fuse swap could do the trick, but it seems to be more complicated than that.
As you can see on the schematics the Japanese version uses a SPST switch (Single-Pole, Single-Throw) and spark suppressor capacitor with a 120Ohm resistor.
To my surprise the European version uses a DPST switch and no (?) spark suppression components.
If I could find a replacement DPST switch, my problem would be solved but it is near impossible to track down a 37 y.o. part.
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By looking at the Australian version , I have noticed that it uses the same SPST switch as the Japanese version with no spark suppression components.
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If I modify the psu according to the Australian specs, I am quite confident that it should work but I can not understand why the European version uses a different switch than the Australian version. Also I can not understand why both European and Australian versions do not use any spark suppression components. ( the GENERAL/ Universal version has these components)
Any thoughts/ suggestions would be deeply appreciated.
Thanks

Re: Power supply conversion from 100V to 230V.

Posted: Sat Dec 20, 2014 8:33 pm
by db0451
To confirm, have you already sourced the actual transformer? Because it seems to have different part numbers between the two voltages, so simply replacing a switch should not suffice on its own.

Re: Power supply conversion from 100V to 230V.

Posted: Sat Dec 20, 2014 9:08 pm
by Yekuku
Thanks for the reply;)
There is no chance of sourcing the original GA80671 transformer (European/Australian/Universal) as a replacement part.
I am planning on swapping the GA80661 (Japan/US) that I have, with a custom 75W toroidal center tapped transformer 18V-0-18V. Also planning on replacing the 1A Fuse with a 400mA/250V. Thats the easy part so far.
What I cant understand is why they used a DPST power switch in the European version opposed to the SPST used in the Australian version and why there is no spark suppression components on the European/Australian versions.
Since I cant source an original DPST switch, I am planning on using the Australian version with a custom transformer in Europe (230V) but I have to be 1000% sure about it.

Re: Power supply conversion from 100V to 230V.

Posted: Sat Dec 20, 2014 11:39 pm
by Hybrid88
My theory would be that it would've been because of tighter regulations in the EU - switching the active *and* the neutral is safer than simply switching the active. Hence the need for a DPST.

As you say finding an identical DPST probably won't happen, so long as you have the appropriate fuse, required power rating and secondary taps for the transformer I don't see why it shouldn't be fine. If in doubt disconnect the Power Supply so you can test the secondary voltages without danger of damaging anything down the line (Obviously be safe when doing that. Hook up the meter first, then switch the power on/off from a distance).

Also chances are the secondary voltages will need a calibration once the new transformer is in.

Of course if you're really not confident with it, best take it to a tech :geek:

Re: Power supply conversion from 100V to 230V.

Posted: Sat Dec 20, 2014 11:41 pm
by db0451
Ah, I see. It sounds a bit difficult but definitely possible :)

I have a few 100~120 V units that I would like to similarly replace their PSUs, but I lack enough knowledge to create new PSUs, and none of these units seem to be directly compatible with e.g. ATX supplies; they always need strange combinations of voltages, or too high current, or something. Just another peril of retro technology :lol:

Good luck anyway!

Re: Power supply conversion from 100V to 230V.

Posted: Mon Dec 22, 2014 1:43 am
by rschnier
Hybrid88 wrote:My theory would be that it would've been because of tighter regulations in the EU - switching the active *and* the neutral is safer than simply switching the active. Hence the need for a DPST.
Basically correct, however for what it's worth -- in Europe, both lines are active and there is no "neutral" (i.e. tied to ground or 0 V) as there is on 120V power in the USA. Using a SPST switch would technically work, in that it would break the circuit and prevent power from flowing, but it would leave voltage on the wires inside the unit when it's powered off -- generally considered unsafe.

Actually, it's the same on 240V circuits in the USA, which is why the circuit breaker for the house circuits powering the clothes dryer, range, etc. is a double-pole rather than a single-pole.

Re: Power supply conversion from 100V to 230V.

Posted: Tue Dec 23, 2014 10:20 am
by Hybrid88
rschnier wrote:
Hybrid88 wrote:My theory would be that it would've been because of tighter regulations in the EU - switching the active *and* the neutral is safer than simply switching the active. Hence the need for a DPST.
Basically correct, however for what it's worth -- in Europe, both lines are active and there is no "neutral" (i.e. tied to ground or 0 V) as there is on 120V power in the USA. Using a SPST switch would technically work, in that it would break the circuit and prevent power from flowing, but it would leave voltage on the wires inside the unit when it's powered off -- generally considered unsafe.

Actually, it's the same on 240V circuits in the USA, which is why the circuit breaker for the house circuits powering the clothes dryer, range, etc. is a double-pole rather than a single-pole.
I think you're getting the terminology mixed up, neutral isn't ever tied to ground, the earth pin is.

In a DC system there is a Positive and Negative with the electrons flowing constantly from one to the other, in an AC system (which mains power is) you have an Active and Neutral both having charge going in and out of them, the Earth or Ground pin is connected to the unit's chassis to safely discharge it if it becomes live, thus avoiding potential electrocution.

I think what you're talking about is when they were less safe and used to not have an Earth, i.e. just an Active and Neutral, hence the two pin plugs. My Japanese MS-20 had a power plug like that, with no grounding.

The mains earth isn't ever switched, for good reason.

Re: Power supply conversion from 100V to 230V.

Posted: Wed Dec 24, 2014 12:42 am
by Steve Jones
There may be suppressor caps on the 110 version as they would draw more current than the 240V version. The Star generator system as used in Australia is definitely very different than the Delta generator system used in Europe with regards grounding. Using a DPDT switch improves safety in all situations as it is not unheard of for active and neutral to be transposed if an electrician makes an error in a building's wiring.

Re: Power supply conversion from 100V to 230V.

Posted: Thu Jan 01, 2015 9:06 pm
by rschnier
Hybrid88 wrote:
rschnier wrote: Actually, it's the same on 240V circuits in the USA, which is why the circuit breaker for the house circuits powering the clothes dryer, range, etc. is a double-pole rather than a single-pole.
I think you're getting the terminology mixed up, neutral isn't ever tied to ground, the earth pin is.
As I said, in the USA, the neutral line (center tap of 240V secondary coming from the transformer out on the street) is tied to earth ground at the point where the electrical service enters the residence. This is required nationwide on every service. Therefore, 120V circuits -- the kind that would power a synth -- need only to interrupt one side of the circuit (the non-grounded leg) since the other leg has been tied to earth at the service entrance and is at 0V relative to the earth. However, 240V circuits, like would be used for a range or clothes dryer, need to interrupt both sides of the circuit in order to not have live voltage present, as they would in Europe. That's what I was speaking of.

Re: Power supply conversion from 100V to 230V.

Posted: Thu Jan 01, 2015 10:05 pm
by Steve Jones
rschnier wrote:
Hybrid88 wrote:
rschnier wrote: Actually, it's the same on 240V circuits in the USA, which is why the circuit breaker for the house circuits powering the clothes dryer, range, etc. is a double-pole rather than a single-pole.
I think you're getting the terminology mixed up, neutral isn't ever tied to ground, the earth pin is.
As I said, in the USA, the neutral line (center tap of 240V secondary coming from the transformer out on the street) is tied to earth ground at the point where the electrical service enters the residence. This is required nationwide on every service. Therefore, 120V circuits -- the kind that would power a synth -- need only to interrupt one side of the circuit (the non-grounded leg) since the other leg has been tied to earth at the service entrance and is at 0V relative to the earth. However, 240V circuits, like would be used for a range or clothes dryer, need to interrupt both sides of the circuit in order to not have live voltage present, as they would in Europe. That's what I was speaking of.
Australian and Euro power, while both in the 220-240V range are very different. Europe wires the three coils of their generators in a Delta (triangle) configuration and Australia uses a star formation with the centre of the star tied to ground at the power station. So in Australia there is always zero Volts between neutral and earth. I think that the neutral is bonded to ground at the main panel rather than at sub panels here but I am not an electrician so I don't know the exact rules there.

Re: Power supply conversion from 100V to 230V.

Posted: Mon Jan 05, 2015 6:27 pm
by rschnier
^ ^ Thanks, that's good info. I always find it very interesting when looking at differences in power supply requirements among different countries. Cheers!

Re: Power supply conversion from 100V to 230V.

Posted: Tue Jan 06, 2015 4:14 am
by Hybrid88
Interesting, didn't know that :)

Re: Power supply conversion from 100V to 230V.

Posted: Sat Feb 21, 2015 8:38 pm
by Yekuku
Due to some life changing events, I was not able to keep up with this thread .

After doing my research , the most logical explanation that i have found about DPST in European PSUs, is that a lot of European countries use symmetrical plugs like schuko and when plugged in the outlet , there is no way of knowing which is the Live/Phase wire and which is the neutral, so for safety reasons, DPST switches are used in order to cut both connections.

thank you all for sharing your knowledge, it was really informative.

Re: Power supply conversion from 100V to 230V.

Posted: Mon Feb 23, 2015 11:15 pm
by SQLGuy
When we lived in Belgium, our apartment building used two-phase 230V, so, as mentioned earlier in this thread by others, both lines were "hot" relative to ground. Not all buildings were wired this way. Some (mostly newer ones) used a 230V hot + neutral, rather than two-phase phase hot.

In any case, the prevalence of two-phase 230V supply is probably why a double-pole switch is used. If you can't find a suitable switch, you could use a relay like this one (http://www.mouser.com/ProductDetail/Omr ... dqvMLZs%3d) with the existing switch switching current to its coil.