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electricity question ...
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author electricity question ...
haricots
I wasn't sure what section to post this in so I thought this might be the best place. Are there any issues with using a synth rated for 100V operation in a 120V environment? I've been told it's ok but I'm assuming it puts a bit of stress on the electronics. Any advice?
Rex Coil 7
haricots wrote:
I wasn't sure what section to post this in so I thought this might be the best place. Are there any issues with using a synth rated for 100V operation in a 120V environment? I've been told it's ok but I'm assuming it puts a bit of stress on the electronics. Any advice?
STOP! Don't plug it in, please. You can get what is known as a step-down transformer for around $25.00 (or even less). Here, take a look, this is one that I use with some of my rack gear. They're all over eBay and quite useful for gear that was made to be used in Japan. I've found some really excellent deals on gear from Japan, but it's almost all 100v. This little converter takes care of the issue very well. I know it looks giant in the picture, but it's only about 4" x 3" x 3" (roughly). Built like a murder weapon. you just plug it into your 120v outlet, and plug the 100v device into the 100v outlet on the box. Done!

haricots
Thanks Rex. I'm contemplating buying a Roland System 100-101 from a user who got it from Japan and has been using it in North America for years without issue (@100V). I have no problem buying one of these transformers but now I'm wondering if the components in the synth might be affected by the extra voltage put on them for years.
Rex Coil 7
haricots wrote:
Thanks Rex. I'm contemplating buying a Roland System 100-101 from a user who got it from Japan and has been using it in North America for years without issue (@100V). I have no problem buying one of these transformers but now I'm wondering if the components in the synth might be affected by the extra voltage put on them for years.
Now there's the question.

Here in the US the electrical standards are plus or minus 10%. So if a device is rated at (let's say) 120v input, it should be able to deal with input voltages from 108v to 132v. So if that synth is constructed to the same standards (poor choice of words on my part there .. but we'll go with it) and it's rated at 100v, it's should be ok from 90v to 110v. IF it's produced with the same electrical standards for appliances.

The little transformer is $25 bucks of insurance to protect whatever that synth is worth.

I ran several pieces of Yamaha gear with it for a good while. Never a single issue. A well spent $25 bucks!

thumbs up
cornutt
haricots wrote:
Thanks Rex. I'm contemplating buying a Roland System 100-101 from a user who got it from Japan and has been using it in North America for years without issue (@100V).


Some power supplies have transformer taps that you can move (usually takes a soldering iron) to accommodate different voltages. The seller of your friend's System 100 may have done that before he sent it over. I wouldn't run a 100V power supply on 120V unless the label says it is rated for it.
Mungo
Rex Coil 7 wrote:
haricots wrote:
Thanks Rex. I'm contemplating buying a Roland System 100-101 from a user who got it from Japan and has been using it in North America for years without issue (@100V). I have no problem buying one of these transformers but now I'm wondering if the components in the synth might be affected by the extra voltage put on them for years.
Now there's the question.

Here in the US the electrical standards are plus or minus 10%. So if a device is rated at (let's say) 120v input, it should be able to deal with input voltages from 108v to 132v. So if that synth is constructed to the same standards (poor choice of words on my part there .. but we'll go with it) and it's rated at 100v, it's should be ok from 90v to 110v. IF it's produced with the same electrical standards for appliances.

The little transformer is $25 bucks of insurance to protect whatever that synth is worth.

I ran several pieces of Yamaha gear with it for a good while. Never a single issue. A well spent $25 bucks!

thumbs up
Tolerance is the key here, without further information you don't know how far the manufacturer allowed for. Some equipment is ok from 80-130V (or 200-250V for the other half of the world). But there have been cases where the margin was not enough and equipment designed for 220V or 230V European supplies failed on UK/Australian 240V supplies.
UltraViolet
If it has a regulated power supply inside then the regulator would have protected everything downstream. In this case only the power transformer and filter capacitors would have been potentially damaged by the higher line voltage. The capacitors should be fairly easy to replace if damaged, but finding a compatible power transformer might be a challenge today (years ago it would have been easy to find).
devinw1
Yeah as others have said it depends on the gear and what tolerances it can accept. The step down transformer would indeed be the safe bet. Or, you get a hold of the schematics for the PSU and do any re-engineering that’s necessary to make it work happily at 120V.
LektroiD
If the synth is working fine, there's no reason not to buy it.

The regulators would be the main thing that's been hammered here, if anything, as the transformer would have provided a higher secondary voltage - 20% increase at the primary = 20% increase at the secondary (which might result in an overheating issue if the heat sinks aren't up to it)...

The transformer's secondary voltage is not clear on the service manual, but say the transformer has a primary voltage of 100V and a secondary voltage of 15V, if you put 120V at the primary, then you'll get 18V at the secondary. The regulators used in the System 100 are 723CN, which can handle up to 40V at the input, and are set to 14V at the output. So it all depends what the transformer is kicking out at the secondary?

The 470µF smoothing capacitors should not be afftected as they are rated for 35V (unless the secondary is higher than that), although I would change these as a matter of course due to age - use decent =>105ºC branded caps (nichicon, panasonic, etc).

Also check the transformer for input taps, it seems there are two main transformers used in the System100; 100V-120V and 220V-250V. Yours will be in spec, check to see if it has a 120V tap, set as necessary.

At the end of the day, buy the synth if it works, replace the 2x 470µF smoothing caps, set the transformer tap, follow the calibration procedure in the service manual for the PSU (repeat for 101 & 102) and enjoy!
Rex Coil 7
LektroiD wrote:
... At the end of the day, buy the synth if it works, replace the 2x 470µF smoothing caps, set the transformer tap, follow the calibration procedure in the service manual for the PSU (repeat for 101 & 102) and enjoy!
... or just lay out the $25 bucks for the conversion transformer, which can be used to power other 100v devices if need be.

So ....

"Just" replace the caps (after they are sourced and paid for).

"Just" rewire the stock transformer.

"Just" recalibrate the rewired stock transformer.


It's not like there is the potential for ten different things to foul up with that plan if not done with an experienced hand.

I mean, what could go wrong?

meh
LektroiD
Rex Coil 7 wrote:
LektroiD wrote:
... At the end of the day, buy the synth if it works, replace the 2x 470µF smoothing caps, set the transformer tap, follow the calibration procedure in the service manual for the PSU (repeat for 101 & 102) and enjoy!
... or just lay out the $25 bucks for the conversion transformer, which can be used to power other 100v devices if need be.

So ....

"Just" replace the caps (after they are sourced and paid for).

"Just" rewire the stock transformer.

"Just" recalibrate the rewired stock transformer.


It's not like there is the potential for ten different things to foul up with that plan if not done with an experienced hand.

I mean, what could go wrong?

meh


None of this is rocket science.

If something's posted in a DIY forum, then expect a DIY solution wink
UltraViolet
Fairly simple for someone with a good amount of build experience and a good understanding of electricity and electronics. I agree with Rex Coil 7 that some caution is in order. The OP seemed to be asking because of not having a good understanding of power systems.
LektroiD
UltraViolet wrote:
Fairly simple for someone with a good amount of build experience and a good understanding of electricity and electronics. I agree with Rex Coil 7 that some caution is in order. The OP seemed to be asking because of not having a good understanding of power systems.


I noticed that. This is why I explained how things work clearly.
fuzzbass
LektroiD wrote:
UltraViolet wrote:
Fairly simple for someone with a good amount of build experience and a good understanding of electricity and electronics. I agree with Rex Coil 7 that some caution is in order. The OP seemed to be asking because of not having a good understanding of power systems.


I noticed that. This is why I explained how things work clearly.


Both approaches are valid, but for benefit of the OP, is should be said that the mains power section inside the synth case is the part of the circuit that can kill or burn down the home of a person who is not versed in the risks and precautions.
Graham Hinton
haricots wrote:
I'm contemplating buying a Roland System 100-101 from a user who got it from Japan and has been using it in North America for years without issue (@100V).


It was common practise by Japanese Synthesizer manufacturers in the '70s/80s to fit different power supplies depending on what world region it was sold to.
The nominal Japanese 100Vac was often as low as 89Vac in practise and 120V linear power supplies would drop out in Japan.

Look at the service manual, all the information you need is there. It is fitted with one transformer for 100-120V (Japan and US) and another for 220-250V (Europe and UK).
Both transformers have a tap on the primary, you would need the higher 120V tap. If you run it on the 100V tap it may overheat the PSU components and shorten its lifetime.

If you post a picture of the transformer wiring we can identify which tap it is set to. (Hopefully) needless to say: disconnect the power cable before opening it.
Grumble
Just a side note: When our research group bought one of the first computers of the university (a PDP8 we're not worthy ) the power supply was wired for 110 volt...
The technician who was to install the computer, plugged it in without checking the settings of the power supply.
Mind you, at that time the computer costs 100.000 guilder (give or take).

The computer: Dead Banana
mskala
If it ain't broke, don't fix it.
Grumble
mskala wrote:
If it ain't broke, don't fix it.

It went broken after that help
mskala
Grumble wrote:
mskala wrote:
If it ain't broke, don't fix it.

It went broken after that :help:


Yeah, I was referring to the OP's question, not your PDP8. Different situation because the synth has been running on US power for many years already.
Modulart_JP
You can find 2 revisions of the Model-101 in Japan.
One that runs on 100V:


And one that runs on 100-120V:


The 1st thing you have to check is which one of those revisions the synth is.
As you can see in the pictures above, it's quite easy, just have a look at the s/n plate.
If it is a 100V one, it can run on 110/120V if the primary of the transformer is wired properly.
You will have to lift up the panel and check if the mod has been done.
If it has not been done, the only thing that has been suffering is the transformer itself.
To fix it, just wire the transformer's primary correctly.
If needed, you can replace the transformer with a new one.
You will need a 2x18V AC, about 10VA.
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