120 and 240VAC: how compatible?

[Mark Hammer]

I bought a second hand Roland D-110 unit this afternoon for what amounts to a song ($35!!).  The seller had a custom connector where the power plug ought to have been.  He assured me the unit was in good working order, but he hadn't used it in a while.  The guy is a bit of a tinkerer, but from his shop he was clearly a professional in such matters, and apparently installed big home theatres for a living.

I clipped off the custom connector as he suggested, and grafted on a 3-prong plug, identifying first which lead was which on the cable coming out the back of the module.  Verified that all plug prongs are connected appropriately, but the unit would not power on.

Then I noticed on the back of the unit that it wants 240VAC.  Is this a problem, and if so how would I fix it?

[stallik]

Step up transformer  would be the easiest solution. It must be possible to to convert the power supply to 110v but I bet it's not going to be as simple as just a transformer replacement. Either way, it'll increase your investment in the unit.

[Mark Hammer]

I sent the seller a note asking about the power situation.  He seems like a decent guy, and we had a very nice chat, but I don't expect to get a reply from him as quickly as I get one here.

[mozz]

If it has a power transformer, sometimes they have windings for both 120 and 240. But it may have a different transformer for each voltage.

[Rob Strand]

Upfront it's not 100% clear what voltage the transformer is inside.   The guy may have done something weird to it.

Assuming everything is factory:

A step-up from 110V to 240V would work.  These can be isolating or non-isolating.  Both will work.

The service manual (p8) shows the transformer, **
https://www.synthxl.com/wp-content/uploads/2017/12/Roland-D110-Service-Notes.pdf

It looks like a different transformer is used for each voltage - since a different p/n is given for each voltage.    The way the mains wiring is drawn looks a bit ambiguous.  There is an "all"  white in terminal S02, but also an unconnected terminal with colored wires for each voltage on S03.  The way the transformer is drawn makes it looks like the S03 windings are taps.  A terrible way to draw mains connections.    The transformer might even have a thermal fuse inside, since there's no mains fuse.

You could replace the transformer but the trick then is getting the correct secondary voltages and the correct VA rating.   The extra secondary winding to the 5V regulator (yellow wires) makes it more difficult to find an off-the shelf transformer.  Also you don't know what proportion of VA is assigned to the +/- 15V part of the circuit and the 5V part of the circuit.  The uncertainty of the thermal fuse is another hassle.
[measuring the primary and secondary resistances can help put bounds on the VA ratings, provided the primary ans secondary voltage of the transformer is known.  The physical size helps as well.]

You would also have change the mains plug (or plug+ cable) to a 110V type.  It is generally illegal (and a hazard) to use the wrong type of plug on equipment.

A factory transformer might be hard to get and expensive.  I guess you could contact Roland.
A step-up transformer could also be expensive but as far a minimizing work it's an easy way forward (*if* the unit is a genuine 240V unit.)

** Edit
Maybe the transformer wire colors or markings will help you identify the transformer voltage.

[Toy Sun]

I lived in Europe for 10 years and used a lot of US-purchased equipment in various ways. It's true the best thing is to find that the internal transformer is multi-tap and get that working. It's the way it was designed and it all stays stock. But sounds like that's not an option.
The other end of the spectrum is to use a standalone transformer, ideally with built in cables and sockets that removes all doubt and risk of misconnection (so that would be a US NEMA male plug on the 120v side and a EU Schuko socket on the female side. Grounding is nice, too, but I've used some kludgy stuff for that before.
In between is where you are now, so just work carefully and thoughtfully. A mistake is going to be a bummer...

[idy]

If the guy is a "tinkerer" you never know, it could already be converted, and feeding it 240 might smoke it. Just a "you never know." requires a talk with him or some serious recon.

[anotherjim]

Odd that a Japanese company would make it so it needs different transformers. I heard that the Japanese islands have different power grids depending on which (foreign) company installed the first electricity supplies in a region.


The lower 100v/117v primary taps say "Nothing". Presumably, no wire exists in those cases.

[matopotato]

240 vs 110 implies to me that there could also be a variation in frequency? 50Hz for 230/240 networks at least in most of Europe, and in US (&Canada? ) 60Hz for 110 supply.
Nooooo idea if this matters in this case though.

[Mark Hammer]

Heard back from the seller this morning, who said he hadn't used it in so long he couldn't remember exactly, but would look around to see if there was some sort of adapter he had used.  He WAS the person who adapted the end of the power cable in the first place.

As someone once said, we'll see what happens.

[amptramp]

Getting a transformer with supplies for ±15 and +5 may be difficult but on a number of occasions before, I have used two transformers to replace one with the advantage that they would be standard units.

There is one additional suggestion: there are a number of local surplus shops that sell used Lambda power supplies.  I am currently using a single unit with a 5 VDC @ 3A output plus ±12 - 15 VDC @ 1A to power the old 1926 radio I finished last winter.  You could get the same or separate 5 volt and ± supplies and bypass the internal regulators.  Since the existing ones use 7805/7815/7915 regulators, the current should not be a limiting factor.  You can keep the existing EMI filter/switch module.

[ElectricDruid]

I had the same problem in reverse on a Korg Polysix - it was US voltage, and I wanted European 240V.

As others have suggested, it turned out that the internal transformer had taps for both settings, so it was just a question of wiring it up differently.

You might be lucky. Open 'er up and let's have a look!

[Kevin Mitchell]

According to the service sheet, they produced these with 4 different transformer options.
110v, 117v, 220v & 240v
edit - I see anotherjim covered this

Transformers with the additional tap for 5v aren't common. The reason for the extra lower voltage secondary is to prevent the regulator from overheating getting rid of the excessive voltage - a popular issue with old synths like the Prophet 5.

If I had that unit on my bench I'd use a 34Vct transformer and replace the 5v regulator with a DC-DC converter. Like this one;
https://www.mouser.com/ProductDetail/Murata-Power-Solutions/OKI-78SR-5-1.5-W36-C?qs=uJpRT2lXVNXJP%252Bo08dQqJQ%3D%3D

You would then have to jumper the inputs of the 7815 to the 7805 since the other rectifier would no longer be used.

[Rob Strand]

My point was the transformer had different part numbers for each mains voltages.
That means the transformer is unlikely to have mains/primary taps.

Interesting, a transformer is for sale:

https://reverb.com/item/44898862-roland-d110-power-transformer-245-517c-sec-35-0-35-volts-and-8-5-volts


Roland p/n;   245-517C
Primary:    Single winding, 117V,   thick white/yellow wires
Secondary 1: 35.5V 2xRed and presumably black is ct.
Secondary 2: 8.5V  2xYellow

*** only single primary winding shown.
Voltages are readable from the label pic.

*** the yellow + white option is not in the list in the service manual!
but at least the 517 in the Roland part number matches 117V.

The transformer is a low noise R-core type.

Hard to judge VA from the pic. However the service manual indicates 12W so it could be a 20VA R-core transformer.

Proportion of VA between two secondaries unknown as no currents given on label.

I doubt the transformer is 35V-0V-35V like the ad. says.  That's too high for a +/-15V rail.
More likely is 35.5V ct.  ie.  17.75V-0V-17.75V.   
The 8.5V winding looks fine 7.5V or 8.5V windings are very typical for 5V supplies.


Another 117V here but with a green primary wire
https://www.keyboardkountry.com/roland-d-110-transformer/

Standard Catalog:
http://kitamura-kiden.co.jp/common/img/product/pdf/01_Rcoretrance.pdf

They make 10VA, 20VA, 25VA ...

Here's a 245-516NO,
pic: 100V primary, blue and white primaries
https://1.bp.blogspot.com/-Q1B_mq2CXnk/VSIvVwueX6I/AAAAAAAALr4/7JFSw58fhyM/s1600/D110_2.jpg

The part number and Blue wire both match the service manual.

The label is marked 2x17.5V 18VA
Nothing marked for the 8.5V secondary so no idea of rating.
Also no idea if 18VA applies to both secondaries or just the 17.5V-0V-17.5V secondary.

Just for completeness.  Don't know the voltage but the pic here shows the *three* transformer primary wires (S01, S02, S03) = (Brown, White, Red).
https://forums.syntaur.com/t/d-110-power-switch-assembly/609

When the transformer only has two wires S03 is left unconnected.

So there is a case where there are three wires like the service manual shows, but there's also two wire cases (which is where the service manual isn't so clear).   No idea what S03 does.

Some transformers have a Faraday shield but it would be very dangerous to assume S03 is that without proof!
I'd go so far to say it's not a Faraday shield.

[Slowpoke101]

I am just wondering if Mark has opened up the unit in question and had a look at what transformer is actually in there. The original owner may have already replaced the 240V transformer with a different type.

[Rob Strand]

The lower 100v/117v primary taps say "Nothing". Presumably, no wire exists in those cases.

OK I think I know what's going on now.

The 100V and 117V only have two wires.  The transformers for 100V and 117V have different part numbers.

The 220V and 240V models have three wires.  The same transformer p/n is used for each. 
The white wire is primary/mains common tap.  The brown wire is the 220V tap.  The red wire is the 240V tap.
The wire which goes to S01 is the tap which is used.
The wire which goes to S03 is the unused tap.   S03 is just a dummy connection to hang the unused tap.

Everything seems consistent with pics and service manual.

The only inconsistency is the wire color used for the mains on the 117V transformer.  It seems to vary  (Green, Yellow) and never matches the grey color in the service manual.  (Could speculate the other colors are 110V and 120V but the p/n is the same as the 117V and the transformers are marked 117V!)

[anotherjim]

I'm always pleasantly surprised if transformer wire colours conform 100% to the schematic. Those colours can change between production runs. Manuals don't get updated for it, presumably official service centres get a memo about it.
Anyway, that's why I picked up on the 3rd wire as an easy tell whether you have a 220/240 traffy, no matter what the colours might be.

[anotherjim]

Another thought, don't some 110v/60Hz places get x2 balanced supply phases so heavy loads can run off 220v without needing heavier wiring?

[Mark Hammer]

I am just wondering if Mark has opened up the unit in question and had a look at what transformer is actually in there. The original owner may have already replaced the 240V transformer with a different type.

1) I've been opening up stuff to "see what's in there" since about 1956.  It's a bad habit.  So, rather surprising that I haven't opened it up yet.

2) The previous owner had clipped the normal plug end off the power cable, and replaced it with a pin jack like what we used to see on the end of the power-supply cables in our computers that would go to hard and floppy drives.  At first, I thought it was just for some sort of custom power-sharing thing, but after corresponding with him, realized it was for using an adapter cable that would plug into a step-up transformer unit.  He looked for those things, but so far has been unable to re-locate them.  He did do a bit of an Amazon search on my behalf and found some suitable step-up units for under $25.

[PRR]

..don't some 110v/60Hz places get x2 balanced supply phases so heavy loads can run off 220v .....

Not on the same outlet.

My lamp outlets are 120V. My dryer outlet is 240V.(*) I'm sure Mark wants a Canadian lamp outlet (120V) rather than have an electrician bring a 9600W dryer outlet to his playing room for a mere 25W load.

(*) OK, my cooker is fed by a 120V/240V system, historically so 220V burners could be run at part-power and so stock 110v clock/timers would work; incidentally for a hi-power 110V coffee percolator or clothes-iron in a vintage kitchen which may not have much other electricity. Again, not the way Mark should go. The plug-socket set alone for a 4-wire stove costs more than his whole synth.