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The right AC Adapter for Roland SH 101?

Posted: Mon Jan 25, 2010 11:05 pm
by phoenix224
Hello,

I just bought a Roland SH 101 and I have a question about getting the right AC adapter for the synth.

I bought the following AC adapter for the 101 from midimusicsales on Ebay:

http://cgi.ebay.com/NEW-AC-ADAPTER-for- ... 5ad3ccd8ef

It is a 9VDC adapter with a 500 milliamp rating, tip negative, sleeve positive.

Today I noticed a 101 AC adapter with a different milliamp rating, sold by chipforbrains on Ebay:

http://cgi.ebay.com/boss-psa-120-compat ... 439bdfd474

This listing posts the following specs: 9v, 300ma 110v for N. America. The listing also warns against using the wrong AC adapter, and identifies this adapter as the one with "correct specs".

Obviously I want to avoid damaging the 101. So which is the correct milliamp rating: 500 or 300 milliamps?

Any insight is greatly appreciated.

Re: The right AC Adapter for Roland SH 101?

Posted: Mon Jan 25, 2010 11:28 pm
by Arturo00
I believe this is it: BOSS PSA (120) Roland AC adapter (12449543).

I can verify when I get home.

As for damaging the thing, I wouldn't worry about it. If the psu provides 500mA and the synth requires 300mA, it'll only draw what it needs. If it's the opposite, i think your psu will c**p out before anything. As long as all other things are equal (ie. Voltage and polarity).

Good luck!

Re: The right AC Adapter for Roland SH 101?

Posted: Mon Jan 25, 2010 11:31 pm
by clubbedtodeath
As I understand it, the synth will only draw the current in requires - so as long as there's enough amps being supplied by the adapter, you'll be okay.

The key thing is to make sure the adapter voltage is the same as the specs - a 12v supply connected to a 9v synth could fry circuitry.

Re: The right AC Adapter for Roland SH 101?

Posted: Mon Jan 25, 2010 11:33 pm
by Maschinengeist
Better go with the 500mA. It won't damage your 101. The only thing that can damage it is a wrong voltage and/or the wrong polarity (+/-).

Re: The right AC Adapter for Roland SH 101?

Posted: Mon Jan 25, 2010 11:34 pm
by phoenix224
Thanks for the info!

Re: The right AC Adapter for Roland SH 101?

Posted: Mon Jan 25, 2010 11:46 pm
by Solderman
This subject comes up so often, there should be a sticky. Indeed for most x0x boxen and synths, the Boss PSA wall warts are best, primarily because in addition to the correct voltage, they are regulated, so cannot change voltage with a load not rated for the power supply. An incorrect voltage can damage the power supply circuit, and iirc, most x0x devices produce ground hum if the voltage is off too much, anyway.

Re: The right AC Adapter for Roland SH 101?

Posted: Tue Jan 26, 2010 2:18 am
by Arturo00
Just to verify, my 101 uses a Boss PSA-120S (9VDC, 500mA, - center)!

Re: The right AC Adapter for Roland SH 101?

Posted: Tue Jan 26, 2010 3:40 am
by phoenix224
Arturo00,

When you say "- center", is this the same thing as "Tip negative, sleeve positive"? That's what the specifications say for the adapter I bought.

Thanks.

Re: The right AC Adapter for Roland SH 101?

Posted: Tue Jan 26, 2010 4:28 am
by Scories
I have a PSA-120 too, I use the same as my SP-202 and it's the best. I think it's 200mA.

I used to have higher amperage and the 101 was getting noisy, the lfo pitch bent was not working and the sound was not quite right.

Re: The right AC Adapter for Roland SH 101?

Posted: Tue Jan 26, 2010 5:50 am
by Arturo00
phoenix224 wrote:Arturo00,

When you say "- center", is this the same thing as "Tip negative, sleeve positive"? That's what the specifications say for the adapter I bought.

Thanks.
Precisely.

Re: The right AC Adapter for Roland SH 101?

Posted: Tue Jan 26, 2010 8:03 am
by EmptySet
Solderman wrote:This subject comes up so often, there should be a sticky. Indeed for most x0x boxen and synths, the Boss PSA wall warts are best…
Actually, I'm pretty sure that my x0xb0x uses Volts AC, not VDC. Thus, I don't think this adapter is at all suitable for the x0xb0x, in particular.

Re: The right AC Adapter for Roland SH 101?

Posted: Tue Jan 26, 2010 8:59 am
by NB23
I'm using the Boss PS-120T 200mA not the S version. Now my SH-101 is silent. With the other power supplies the SH-101 is very noisy. I found it in the archives here and it worked.

Re: The right AC Adapter for Roland SH 101?

Posted: Tue Jan 26, 2010 12:47 pm
by Altitude
NB23 wrote:I'm using the Boss PS-120T 200mA not the S version. Now my SH-101 is silent. With the other power supplies the SH-101 is very noisy. I found it in the archives here and it worked.

There is a good reason for that, an unregulated DC adapter is designed to work at a particular load, the further you go off from that load, the less accurate the voltage output will be so if you are using a 1 amp rated adapter with something that draws 100 mA, chances are it will NOT be delivering the correct voltage at all. This is a common way to damage a 606 or 303 both of which draw very little current, the PSU may say 9V DC but actually is putting out 13V+ and ends up damaging the power transistor. Chances are although you were using something that said 9V, it was not putting out 9V hence the noise and weird behavior

Re: The right AC Adapter for Roland SH 101?

Posted: Tue Jan 26, 2010 4:50 pm
by Solderman
EmptySet wrote:
Solderman wrote:This subject comes up so often, there should be a sticky. Indeed for most x0x boxen and synths, the Boss PSA wall warts are best…
Actually, I'm pretty sure that my x0xb0x uses Volts AC, not VDC. Thus, I don't think this adapter is at all suitable for the x0xb0x, in particular.
I should clarify that I meant all Roland vintage x0x.