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Can I plug in 100v Roland SH-1 into USA wall socket?
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Can I plug in 100v Roland SH-1 into USA wall socket?
samplebias2
Figured this is the best place to ask.

Just got a Roland SH-1, the plate by power supply says 100v. 50hz/60hz 10 W

My SVC-350 says 117v I was told it's a rare USA model.

Can I just plug in this SH-1 to the wall (I am in California, USA) safely or do I need a transformer of some kind? Any help greatly appreciated while I do more research!
Modulart_JP
To test it a few minutes, it will be OK.
But in the long term, you want to replace the internal transformer.
It is a easy job for a experienced tech.
Avoid external 117V->100V step-down transformers.
samplebias2
Modulart_JP wrote:

Avoid external 117V->100V step-down transformers.



Hmm care to elaborate? I was about to go pick one up, they seem to be a common solution to using Japan products in USA. Something like this:

https://www.frys.com/product/8070344?site=sr:SEARCH:MAIN_RSLT_PG
KSS
You're smart to do more research. On page 12 of the PDF service manual downloaded from manualslib.com ,which is marked page 11, is the information you need for your research.

Shown there is that Roland designed three different power supply arrangements. The PCB is the same in all cases. The transformer is not.

Since Roland could have just as easily made only two power supplies to give you a 117/100 option instead of the 100, 117, 220/240 option they did, it might be wise to consider that the difference does matter.

Unfortunately as is often the case with synth technical service manuals, Roland have left off some important information. They don't show the secondary voltage for the transformers used.

When you do as you've suggested you'd like to do, you will change the output of the transformer by the difference between 100 and 117. The secondary will be 1.17 times what it would be with the correct transformer. If the output was 30V, it will instead be 35.1V. If the output was 36V, it will instead be 42.12V.

30 and 36 chosen as examples because both are common in vintage synths. 35 also. Looking at the schematic linked above, you see that this voltage first goes to 1N4003 rectifier diodes. Looking up their specs it is seen that these will handle the possible 42.12v no problem.

Next are the filter capacitors. Shown as 470uF, and 35VWDC. This is clearly a problem, if the assumption made about expected transformer secondary output is correct.

Next in line is the voltage regulator. IC101, TA7179P. I did not look this up, but many similar voltage regulators have a 30-something volt max input

I skipped over the pass transistors Q101 and Q102, but you should check their specs too. They're probably sized overly large enough to handle the difference, but it's not a given. They could easily be working at or over their limit since 40V is a typical division level for silicon device ratings.

The conclusion to reach from all this is that you don't really know without direct investigation of that transformer secondary output.

Do you think Roland would approve of ignoring their decision to have three instead of two power supplies? Do you feel lucky?

In the previous reply you were told it will be fine. Maybe Modulart JP has some inside information on that secondary output? If so it is not from the published Roland service manual, which does not list any of the transformers on page 19 of the PDF service document.

I happen to recognize JP from other posts here and elsewhere on the net, so can say he might actually have that personal information. But that is still only a guess educated by reading his other knowledgeable posts. As much as I respect JP, I would not take the advice he shared above without doing my own investigation of the transformer secondary output.

Also would agree that it's better to do the proper internal change than not, but wouldn't go so far as to say never use an external voltage adapting transformer. They are a PITA in several ways, but there's nothing electrically wrong with using them when done correctly.

You can discover the winding ratio for your transformer in a few different ways. Suggest you make that part of your research.
samplebias2
Thanks for the detailed responses. I opted for a unit specifically for using Japanese electronics in the USA (117v to 100v) seems to be working great, no hums, buzzes or smells.

Unfortunately the eBay seller described the unit as

"100% perfect working condition. Really beautiful condition, with all original knobs, keys, switches, sliders, logos, etc. present and accounted for."

A 5 minute tour around the unit shows the highpass filter barely works, pitchbend is really unstable, the potentiometer is really worn (only works when sensitivity slider is all they way up, and that slider has issues as well)

I expect a unit of this age to have some quirks but this is unacceptable. I don't have a can of compressed air handy but I can see myself filing an eBay claim tomorrow night.
Modulart_JP
Well...
Yes I happen to know the SH1 very well since I serviced many of them (more than I can remember).
The transformer is 2x 18V.
As said before, you can run it on 117V for a few minutes and it'd be OK but that's all.
In the long term, the best option is to replace the transformer.
Mouser or other suppliers will have 2x 18V transformers.
The problem with external step-down transformers is that most of the time, people buy those cheap travel transformers.
They are not designed to run for hours and also they can induce hums and other audio issues.
I assumed that you were referring to such transformers.
The one you pointed to is a more serious affair and should be OK. (though 300W for a 10W synth is overkill)
However, if you want to move the synth around you have to carry the transformer.
A 300W one must weigh around 4/5 Kg, almost as heavy as the synth itself...
d'oh!
Modulart_JP
samplebias2 wrote:
A 5 minute tour around the unit shows the highpass filter barely works, pitchbend is really unstable, the potentiometer is really worn (only works when sensitivity slider is all they way up, and that slider has issues as well)


The SH1 has 2 major recurrent issues: pots and jacks.
The jacks are mounted vertically and with time, the tension on them due to the cables makes the solders crack.
The sliders quality is very bad.
Maybe they are the worst pots Roland ever used.
And don't put some Deoxit in them because it feels better for 5 min and then you can barely move the pots...
Think ARP synth sliders... twisted
That's why nowadays it is not recommended at all to buy a SH1 that you cannot test.
Most of the time you will pay a premium for many unpleasant surprises...
It's too bad because that little monster sounds actually pretty good.
minime123
Quote:
Unfortunately the eBay seller described the unit as

"100% perfect working condition. Really beautiful condition, with all original knobs, keys, switches, sliders, logos, etc. present and accounted for."

A 5 minute tour around the unit shows the highpass filter barely works, pitchbend is really unstable, the potentiometer is really worn (only works when sensitivity slider is all they way up, and that slider has issues as well)

I expect a unit of this age to have some quirks but this is unacceptable. I don't have a can of compressed air handy but I can see myself filing an eBay claim tomorrow night.


it's shocking how many sellers misrepresent their items.
while it's completely unrealistic to think a 30-40 year old synth that hasnt been serviced is going to be in perfect working order, you shouldn't have to write off quirks as typical - its the seller's responsibility to describe their items accurately. if he didnt take the time to test it properly or didnt have the knowledge required, he should've just said that and sold it as untested or not fully tested. good luck with the claim, please let us know how that turns out.
samplebias2
minime123 wrote:


it's shocking how many sellers misrepresent their items.
while it's completely unrealistic to think a 30-40 year old synth that hasnt been serviced is going to be in perfect working order, you shouldn't have to write off quirks as typical - its the seller's responsibility to describe their items accurately. if he didnt take the time to test it properly or didnt have the knowledge required, he should've just said that and sold it as untested or not fully tested. good luck with the claim, please let us know how that turns out.



Thanks, the seller appears to be willing to work with me, filed a claim with UPS, and offered a full or partial refund, but only replies to email in the early A.M. I think I'll ask for a 40% refund and apply it to repairing the pitch bend, which seems to be both the potentiometer and the "Sensitivity" or range slider. This is a huge issue for resale value (I only want it to perfect a carrier signal for an EMS vocoder which I hope to find a 2000 for sale soon, cash in hand buyer) I will multisample the tones I need and part with this unit.
minime123
Quote:
Thanks, the seller appears to be willing to work with me, filed a claim with UPS, and offered a full or partial refund, but only replies to email in the early A.M. I think I'll ask for a 40% refund and apply it to repairing the pitch bend, which seems to be both the potentiometer and the "Sensitivity" or range slider. This is a huge issue for resale value (I only want it to perfect a carrier signal for an EMS vocoder which I hope to find a 2000 for sale soon, cash in hand buyer) I will multisample the tones I need and part with this unit.


filing a claim with UPS over problems that were present prior to shipping would probably be considered fraud. if the problems really did happen during shipping, then simply removing and reseating connectors should fix them. ask the seller for permission to open the synth up to do this (carefully, making sure you understand proper procedure for safety and to prevent doing damage to the synth).
the claim process, going through the system UPS has used for ages, is designed to save UPS money. in other words, they do whatever they can to reject them, to waste people's time, and to frustrate them so they just go away. if i was in your situation, i would just send it back for a full refund and let the seller deal with it. good luck and keep us posted.
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