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sirlemonhead
Bronze Member
Ireland
64 Posts |
 Posted - 07/07/2005 : 20:43:07
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I have an old HM-2 that requires an ACA adapter to use. I'd rather not power it with a battery as I have a PSA adapter.
Could anyone tell me what I need to remove and bridge on the circuit board so the voltage coming in from the power jack isnt dropped down 3 volts? I presume there's a resister somewhere and possibly somethign else, but i'm unsure as to where they'd be.
Thanks :) |
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 07/07/2005 : 21:20:26
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You're saying that the voltage drops 3V when you use the PSA adapter with it? I have used my own HM-2 with a PSA without any problems so I'm surpised to hear this.
It sounds like there may be some sort of shortcut somewhere that pulls so much current that the adapter can't keep up. As it works with an ACA adapter maybe the plugs are a little different and you somehow get a short within the power connection?
Only guessing... It should work without mods. |
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sirlemonhead
Bronze Member
Ireland
64 Posts |
Posted - 07/07/2005 : 21:34:09
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I thought all the ACA power adapters outputted 12 volts?
When I power the pedal with my Boss PSA adapter (only pedal on it) the light is dim. Adapter works fine with all my other boss pedals. |
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 07/08/2005 : 09:42:52
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I haven't ever used an ACA adaptor but I'm quite sure they're 9V, just as the PSA adaptor. If you have a multimeter you can easily measure this.
I have no idea what could be wrong here. Anyone? |
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Goran
Double Platinum Member
Sweden
2203 Posts |
Posted - 07/08/2005 : 10:09:03
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The ACA is not 9 V, it�s more, 12-14 V if I don�t remeber wrong.
There is "something" in the ACA pedals that limit the 12-14 V to 9V inside the pedal.
When you�re using a PSA together with a PSA-pedal and a ACA-pedal the "something" above is bypassed and the ACA pedal get what it wants. |
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Goran
Double Platinum Member
Sweden
2203 Posts |
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 07/08/2005 : 10:54:44
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I had no idea about this. Learning something new every day... 
I guess there is a possible mod for the pedal then. |
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Goran
Double Platinum Member
Sweden
2203 Posts |
Posted - 07/08/2005 : 11:05:40
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Yes there is, but I wouldn�t do it. I suppose it is a resistor, but I don�t know where to find it...
Just use the pedal together with a PSA-pedal and a PSA supply, much easier, and keep your pedal stock.
Some ACA-pedals work fine with PSA-supply, some sound very thin or really bad.
Of course you need to use a Daisy-chain (is it called that?) from the supply. |
Edited by - Goran on 07/08/2005 11:08:05 |
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Goran
Double Platinum Member
Sweden
2203 Posts |
Posted - 07/08/2005 : 11:14:07
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And there is more to it...
There is an old ACA-supply and a new type of ACA. I read somewhere that the new is no good for the old ACA-pedals, maybe on the link above.
Stinkfoot would clear this matter easy, so, Andreas if you read this please... |
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lightburst
Silver Member
Germany
158 Posts |
Posted - 07/08/2005 : 18:56:56
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The ACA is an unregulated power supply while the PSA delivers 9 volts of regulated power.
The pedals asking for the ACA there is a resistor and a diode connected in row to create a little voltage drop to achive around 9V. This pair must be bridged.
Here is a good advice how to modify your ACA pedal to PSA specs.
http://www.jpl-audio.com/acapsa.html
I�ve done it with my SD-1 and CS-2 bothe asking for a ACA adaptor and it works without any problem
Since I�m a lazy guy I�ve done the "Simplified One Wire Conversion" |
Edited by - lightburst on 07/08/2005 19:02:32 |
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stinkfoot
Silver Member
Sweden
181 Posts |
Posted - 07/13/2005 : 03:27:38
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The ACA pedigree is divided into two eras: pre and post 1997. In the summer of that year, Boss took all the remaining ACA designs and adapted them to work with 9 volts DC. At the same time, they also redesigned the ACA adapter to put out 9vDC unregulated, instead of 12vDC unregulated as before.
The trick with older ACA pedals (pre 1997) is indeed that they have a diode/resistor combo inside, to drop the 12vDC coming in down to about 9vDC. This can easily be modified, if you plan on running the pedal from a 9vDC supply. But chances are you don't have to - all 12 volt ACA pedals will run just fine from a 9vDC supply, as long as they share both the power and signal connection with at least one regular (PSA) pedal. In that case, the common ground between the pedals (as established by the signal cable) will take the diode/resistor combo out of play, giving the ACA pedal full power. Naturally, this will not work if you're using an isolated power source (like a Pedal Power 2).
Try it out - if you power a pre 1997 ACA pedal alongside a regular PSA pedal (using a daisy chain cable or common ground power supply), you will see that the LED will light up fully once there is a signal cable connecting the two. Remove the signal cable, or the power from the PSA pedal, and the LED will dim again (indicating that the ACA pedal isn't getting full voltage).
/Andreas |
Edited by - stinkfoot on 07/13/2005 03:28:46 |
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bossarea
Forum Admin
United Kingdom
3652 Posts |
Posted - 07/13/2005 : 10:06:39
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That explains everything.
I was surprised to learn about the older 12V supply and couldn't understand why I've never had any problems powering my ACA pedals using a 9V supply. It is however a long time since I used only one pedal. My daisychain has been there since the first PSA pedals was released. |
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Mat Grant
Copper Member
United Kingdom
25 Posts |
Posted - 08/04/2005 : 18:31:19
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Hi,
This is interesting stuff! But I have a question:
I have a custom built (alright home made) pedal board with a radio, a boss GT-5, and three pedals: TU-2, OD-2, LS-2 (used to switch between two amps).
I have a pedal power supply called a 'power bank' with 5 or 6 9v outputs. i trhink it is regulated (big caps inside)
I looked at the link and it says the OD-2 is an ACA type, and thus needs 12 volts. But the light comes on ok when it is operated... Do I need to open it up and modify it to be PSA compatible? Will the sound be different as it is getting less volts than it should?
Thanks for any replies, Mat. |
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arcanon1313
Silver Member
USA
414 Posts |
Posted - 08/04/2005 : 19:29:56
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See stinkfoot's post above. I had a problem with my ACA pedals not working properly with my 9v adaptors and then i discovered that if I put a PSA powered pedal in the chian with my ACA pedals everything works just fine. I see that you are using two PSA pedals with your OD-2 Mat, it looks like you should be alright and running full power to your OD-2 as long as you keep using the PSA powered pedals with the OD-2. I should also add that I use a visual sound onespot adaptors with the daisy chain for all my pedals, and since i put the PSA pedals with the ACA pedals everything powers up as it should. if I use only the ACA pedals together I don't get full power and the check lights are dim and the sound quality isn't as good. But you seem to be having no problem with your OD-2 so I wouldn't worry about it. Hope that helps. |
Edited by - arcanon1313 on 08/04/2005 22:36:25 |
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bossFan
Bronze Member
Portugal
97 Posts |
Posted - 09/11/2005 : 19:15:10
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PSA or ACA or whatever...
All you need is a good filtered 12v..14v transformer/rectifier/capacitor and a 7809 voltage regulator.
That will give power to any boss pedal.
It works fine with mine... |
Edited by - bossFan on 09/11/2005 19:16:42 |
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stinkfoot
Silver Member
Sweden
181 Posts |
Posted - 09/11/2005 : 19:44:50
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quote:
Originally posted by Mat Grant
I have a pedal power supply called a 'power bank' with 5 or 6 9v outputs. i trhink it is regulated (big caps inside)
I looked at the link and it says the OD-2 is an ACA type, and thus needs 12 volts. But the light comes on ok when it is operated... Do I need to open it up and modify it to be PSA compatible? Will the sound be different as it is getting less volts than it should?
No, there's no need for modifications, as with your setup the OD-2 is already getting the full voltage it wants (which is why the LED lights up properly). Modifying it will not change anything with your current setup.
The Power Bank is a common ground-type supply (the ground on all outputs are tied together), which works the same way as a daisy chain type of setup. The common ground connection bypasses the voltage limiting components, so the pedal receives full power. Modifiying the pedal is really only needed if you want to run it as the only pedal off a 9vDC supply.
/Andreas |
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Topic |
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Making an ACA pedal work with a PSA adapter
