Found the Japanese manual (http://lib.roland.co.jp/support/jp/manuals/re … 2/SC-D70_j3.pdf) . It only mentions 100 V and says

源プラグは、必ず AC100Vの電源コンセント
に差し込んでください。

which Google translates to

Make sure the power plug is a 100V AC power outlet.
Please plug it in.

I couldn't find a picture of the internals at the moment, but maybe you can bypass the internal power supply and just use a fitting external one

imi wrote on 2020-04-19, 02:11:

I couldn't find a picture of the internals at the moment, but maybe you can bypass the internal power supply and just use a fitting external one

I have been considering doing that, I would just need to determine the required voltage . I would imagine/hope the PSU feeds a linear regulator on the mainboard and that everything runs on 5V downstream .

A service manual would be really nice .

If you do find some internal pictures, please post them .

darry wrote on 2020-04-19, 02:40:

I have been considering doing that, I would just need to determine the required voltage . I would imagine/hope the PSU feeds a l […]
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imi wrote on 2020-04-19, 02:11:

I couldn't find a picture of the internals at the moment, but maybe you can bypass the internal power supply and just use a fitting external one

I have been considering doing that, I would just need to determine the required voltage . I would imagine/hope the PSU feeds a linear regulator on the mainboard and that everything runs on 5V downstream .

A service manual would be really nice .

If you do find some internal pictures, please post them .

With some synths it's more complicated than that.

Anyway, most PSUs are rated for +/- 20% voltage. So it'll likely be fine on 120V.

You could also have a look at the PCB of the power supply to see whether it may indicate alternate arrangements of components for use in different countries (although Roland tends to use different PSU PCBs for each region).

yawetaG wrote on 2020-04-19, 09:14:

Anyway, most PSUs are rated for +/- 20% voltage.

Yes, but that is because mains voltage is, too. In Germany for example, we have 230V mains. But it's allowed to go up to 253V for short moments. That's why any PSU must have such a tolerance. It does not allow you to generally use a mains voltage that is 20% higher by default. It would blow with the very first voltage peak, since in the US, up to 127V are allowed - and that is too much even with the +20%.

darry wrote on 2020-04-19, 02:40:

If you do find some internal pictures, please post them .

well, you're going to get one so that'll probably be easier ^^

I'm pretty sure the PSU is going to be seperate and the internal voltages are going to be generated with linear regulators.

imi wrote on 2020-04-19, 09:35:

darry wrote on 2020-04-19, 02:40:

If you do find some internal pictures, please post them .

well, you're going to get one so that'll probably be easier ^^

I'm pretty sure the PSU is going to be seperate and the internal voltages are going to be generated with linear regulators.

I agree that it will be easy to get picture once I have it, but in view of the current situation with COVID-19 shipping delays, I was hoping to get ahead of the game in case I need to order anything I will need but do not have .

One thing that has not been commented on yet is the fact that the unit they are going to send me was apparently tested at 240V and did not blow up instantly . I do not know if I can reliably deduce anything from that .

I have SC-D70 and there is no AC adaptor included, you'll get just a cable for a power socket. I bought an AC converter, where the output voltage is 110V and it runs fine so far.

Of course there's no AC adaptor included, that's the whole problem. The PSU is inside the unit and take mains directly.

Just received it . Internal PSU looks to be the same as the one described and shown here :
https://www.eevblog.com/forum/repair/switch-m … -supply-107897/

down to the 250V fuse . Now correct me if I am wrong, but if the PSU only handled 100V, there would not be a 250v fuse, would there ? Also the fact that a Roland service note for another product describes it as 100v-240v would be a good indication .

Here are some photos of mine .

darry wrote on 2020-04-21, 18:48:

down to the 250V fuse . Now correct me if I am wrong, but if the PSU only handled 100V, there would not be a 250v fuse, would there ?

The fuse blows when the current limit is exceeded. The voltage of the fuse doesn't tell much about the mains voltage (only that it is certainly not higher than what the fused is rated for).

I wouldn't risk damaging the unit and just buy a transformer.

the model number of the transformer is not the same as in the EEVblog post, so I'd be careful.
is there a voltage rating on the primary side cap? I can't decipher any.

but it seems to be outputting multiple voltages, so just replacing it with an external brick is not going to work.

imi wrote on 2020-04-21, 19:32:

the model number of the transformer is not the same as in the EEVblog post, so I'd be careful.

It's not the same PSU at all, just compare the components and layout. Only looks similar at a first glance.

well it's almost identical, so I'd assume it's just different revisions of the same board, seeing as it has the same model number, but they might very well be using the same board populated with different components.

As said before, the seller said it was tested at 240V with a step up transformer. That would be a good sign, but not conclusive proof of 100v to 240v capability .

imi wrote on 2020-04-21, 19:45:

well it's almost identical

The layout is different enough to assume that these are for different regions/voltages. The section to the right of the transformer T1 is just completely different in layout and components - and that is the primary side which runs from mains.

derSammler wrote on 2020-04-21, 20:07:

imi wrote on 2020-04-21, 19:45:

well it's almost identical

The layout is different enough to assume that these are for different regions/voltages. The section to the right of the transformer T1 is just completely different in layout and components - and that is the primary side which runs from mains.

Probably safer to wait for the step down transformer, then . I just hop that the sender did not damage the PSU by testing it on 240v .

What brand step down transformers would be recommended ? As I mentioned, I have a Kashimura TI-101 on the way, but I have a bad feeling about it .

All other Roland synths from this era use universal transformers (they had since 1999). You can ask Roland US for confirmation but I'd wager to say the SC-D70 is the same.