Vintage BOSS PSA-120 Power Adapters

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Vintage BOSS PSA-120 Power Adapters

Post by Crisp » Sat Oct 08, 2016 12:01 am

I am losing my mind here.

The only power adapters that work reliably for noise free operation on my TR-606, TB-303 and SH-101 are the old school Red and White BOSS PSA-120S power adapters.

The new "low profile" jobbers introduce noise.

I tried several "Jameco" 9V 200ma adapters off of ebay and the last FIVE measured 14V!

Can anybody recommend a viable alternative? The older Boss PSA-120's are getting pretty expensive, plus due to their age the connection to the wallwarts are becoming brittle.

Any advice is greatly appreciated. I may switch exclusively to battery power.

-Steve

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Re: Vintage BOSS PSA-120 Power Adapters

Post by Stab Frenzy » Sat Oct 08, 2016 3:50 am

Crisp wrote:I tried several "Jameco" 9V 200ma adapters off of ebay and the last FIVE measured 14V!
Without a load on them I assume? That's normal behaviour, the voltage regulator won't be functioning correctly without a load, once you plug it in it will be fine.

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Re: Vintage BOSS PSA-120 Power Adapters

Post by Hybrid88 » Sat Oct 08, 2016 10:10 am

Well 200mA is not really enough for a start, the 606 draws up to 150mA, you want a plug pack that can supply at least double that (300mA) to get the correct voltage under load.

As for the SH-101 which draws 1000mA (1 Amp), that's just asking for problems.

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Re: Vintage BOSS PSA-120 Power Adapters

Post by Crisp » Sat Oct 08, 2016 10:38 pm

Hybrid88 wrote:Well 200mA is not really enough for a start, the 606 draws up to 150mA, you want a plug pack that can supply at least double that (300mA) to get the correct voltage under load.

As for the SH-101 which draws 1000mA (1 Amp), that's just asking for problems.
I appreciate your trying to help, but I do not appreciate being provided with false information.

The "official" power supply for an SH-101 is a BOSS PSA-100. These ran at 9V 200mA. Your 1 AMP draw assumption is plain wrong.

200mA is more than enough to power an SH-101, TB-303 and TR-606. Not all together of course. I have been doing this for years.

A BOSS PSA-120 is 9.6 at 200mA. That is the only difference. That whopping 0.6 extra.
Last edited by Crisp on Sat Oct 08, 2016 10:47 pm, edited 1 time in total.

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Re: Vintage BOSS PSA-120 Power Adapters

Post by Crisp » Sat Oct 08, 2016 10:46 pm

Stab Frenzy wrote:
Crisp wrote:I tried several "Jameco" 9V 200ma adapters off of ebay and the last FIVE measured 14V!
Without a load on them I assume? That's normal behaviour, the voltage regulator won't be functioning correctly without a load, once you plug it in it will be fine.
You may be correct, but the fact remains that these Jameco supplies still introduce a debilitating hum. I immediately unplugged the one I received yesterday for fear of frying my TB-303. Also, my older Red and White BOSS PSA-120s measure great. 4 Times now. Separate purchases over the last month from different ebay dealers. Always though I was getting a "lemon". Now, I am not so sure.

Take a look.

Again, my last 4 measured way out of spec.

Image

Image

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Re: Vintage BOSS PSA-120 Power Adapters

Post by Stab Frenzy » Sat Oct 08, 2016 11:52 pm

I'm sorry but putting a multimeter across the open terminals of a linear power supply isn't telling you anything about how that supply will operate when it's in use.

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Re: Vintage BOSS PSA-120 Power Adapters

Post by Crisp » Sun Oct 09, 2016 12:06 am

But from my anecdotal experience, it certainly has. Time and time again. Noise at best. Even with the newer model PSA-120 that have the low profile "one-spot" guitar pedal shape, it emits a hum. This is not audiophile speak...even a disinterested wife or girlfriend would easily hear it.

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Re: Vintage BOSS PSA-120 Power Adapters

Post by Hybrid88 » Sun Oct 09, 2016 11:21 am

Crisp wrote:
Hybrid88 wrote:Well 200mA is not really enough for a start, the 606 draws up to 150mA, you want a plug pack that can supply at least double that (300mA) to get the correct voltage under load.

As for the SH-101 which draws 1000mA (1 Amp), that's just asking for problems.
I appreciate your trying to help, but I do not appreciate being provided with false information.

The "official" power supply for an SH-101 is a BOSS PSA-100. These ran at 9V 200mA. Your 1 AMP draw assumption is plain wrong.

200mA is more than enough to power an SH-101, TB-303 and TR-606. Not all together of course. I have been doing this for years.

A BOSS PSA-120 is 9.6 at 200mA. That is the only difference. That whopping 0.6 extra.
Except it's not an assumption, the irony is you are the one assuming I made an assumption. In actual fact I took the time to read up the SH-101 and TR-606 specs in each manual before trying to help you with this.

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Re: Vintage BOSS PSA-120 Power Adapters

Post by fh991586 » Sun Oct 09, 2016 2:38 pm

The Boss PSA-100 was supplied with the SH-101, as inscribed in the owner's manual. So it's pretty safe to say 200 mA is good enough. No problem to use a PSU that can provide up to 1A, but I now wonder where you got your information...
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Re: Vintage BOSS PSA-120 Power Adapters

Post by Hybrid88 » Sun Oct 09, 2016 3:48 pm

...the owners manual, as I said. See for yourself, page 56 under "Power Consumption"

http://dl.lojinx.com/analoghell/RolandS ... Manual.pdf

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Re: Vintage BOSS PSA-120 Power Adapters

Post by fh991586 » Sun Oct 09, 2016 5:14 pm

Check page 4 of the same manual...

Edit: Power consumption is 1W, not 1A!

Edit #2: This PDF file is mixed up: page 5 of the paper manual is on page 9 of the PDF! And there you see which PSA is ok for the unit (120, 220, 240). I suppose the 100 was for Japan only (lower voltage), and the 120 would be the regular one for North America...
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Re: Vintage BOSS PSA-120 Power Adapters

Post by RichardReeves » Sun Oct 09, 2016 5:16 pm

The manual says 1W consumption, so I = P/V at 9V = 1/9 = 110mA.


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Re: Vintage BOSS PSA-120 Power Adapters

Post by fh991586 » Sun Oct 09, 2016 5:26 pm

That's more like it!
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Re: Vintage BOSS PSA-120 Power Adapters

Post by Hybrid88 » Sun Oct 09, 2016 6:22 pm

Ok yep, got my Watts and Amps confused there, that'll be sleep deprivation for ya, sorry guys! :lol

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Re: Vintage BOSS PSA-120 Power Adapters

Post by grenert » Sun Oct 09, 2016 8:31 pm

Hi, Crisp.
Can you post a photo of the label for your Jameco adapter? Or a link to where you bought it? I couldn't find specs for this one on their website. Please don't take this as an insult, but you have confirmed it is center negative?

Also, the TR606 really is only looking for 6V. Unregulated linear supplies are often much higher than their rated voltage until they supply at their rated current. So, you could probably try a 6V supply (again, center NEGATIVE).

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