Boss CS-2 compressor ACA to PSA mod?

mrsage · August 08, 2005, 11:17:16 PM

I know a few people have successfully modded their CE-2 choruses to take a standard PSA power supply...

Has anyone done this to a CS-2 compressor? How hard is it to pull off? Are there any sites that explain what needs to be jumpered where?

Fret Wire · August 08, 2005, 11:36:09 PM

http://www.jpl-audio.com/acapsa.html

TheBigMan · August 09, 2005, 10:04:33 AM

In the CS-2 it's R38 (470 ohms) and D2 (1S2473) that need to be removed and jumpered. Or you can jumper pads 11 and 12 at the end of the board and leave the parts in place.

cd · August 09, 2005, 10:43:35 AM

I would not remove any parts. There's a blue wire that goes from the PCB to the power jack - cut/unsolder this (on the power jack end) and tape it off. There's a yellow wire that goes from the input jack to the PCB - unsolder the wire from the PCB end and solder it to where the blue wire was on the power jack. Done.

mrsage · August 09, 2005, 01:33:41 PM

Fantastic. Seems easy enough.

Thanks again guys!

plucker · November 29, 2005, 12:27:15 PM

Replaced all the usual caps and did psu mod by cd (cheers) worked a treat still seems to muddy my sound just a little though does anyone have any ideas about a more true bypass sound when off.

This is a great site I only found it by accident so as this is my first post I would like to say hello also.

Thanks

Plucker

0dBVU · November 29, 2005, 04:27:36 PM

Hi guys... hey CD, is that description the same for converting an ACA Boss CE-2 to take a PSA adapter?

By the way, I've generally run ACA pedals on a daisy chained PSA adapter without problem in the past and someone from Boss once told me it would work fine. What are we changing with this mod to take the PSA adapter and why?

Thanks, AR

MartyMart · November 29, 2005, 04:33:33 PM

"Older" Boss pedals were run at up to 12v from ASA, this can cause the LED
to not light up when using a 9v PSA !!
The mod solves this

Marty.

0dBVU · November 29, 2005, 06:23:27 PM

ok, I'm following you... I've found that with a 9volt adapter in the ACA jack the LED runs dim, but with either a 9volt battery or a 9volt adapter with a battery clip adapter attached to the pedal's battery clip... everything runs fine, as would make sense.

I see how the mod would bypass some components on the PCB and would essentially duplicate the path of the battery clip but from the ACA jack. So here's a couple of questions:

-What is the function of the bits we bypassing on the PCB with the mod?

-Is there a disadvantage to running the pedal on 9v instead of 12v (i.e. why does the ACA adapter run the pedals on 12v?

Sorry, I'm just curious

Thanks again for the input!

0dBVU · November 29, 2005, 06:49:55 PM

ahh, I think I've answered my own question. I found this on the net

"For some reason (possibly to help the pedals sound as they were on batteries), Boss decided to run their (ACA) adapters at 12 volts, and then use a resistor (usually 470 ohm) and a silicon diode inside the pedal to reduce the incoming voltage."

so we're simply bypassing the resistor and diode and there should not be any appreciable disadvantage to the mod, especially when considering the advantage of being able to use modern power distribution solutions. sound right?

Thanks again for the info!

cd · November 29, 2005, 07:19:53 PM

Quote from: 0dBVU on November 29, 2005, 06:49:55 PM
ahh, I think I've answered my own question. I found this on the net

"For some reason (possibly to help the pedals sound as they were on batteries), Boss decided to run their (ACA) adapters at 12 volts, and then use a resistor (usually 470 ohm) and a silicon diode inside the pedal to reduce the incoming voltage."

so we're simply bypassing the resistor and diode and there should not be any appreciable disadvantage to the mod, especially when considering the advantage of being able to use modern power distribution solutions. sound right?

Thanks again for the info!

Yes.

Main difference with an ACA adapter is that it provides unregulated voltage - I don't know, maybe simple regulators were way expensive way back when. By doing the mod I described above, you bypass the resistor and diode. Disadvantage to this is sometimes the LED doesn't light up as much (or at all) - if this is the case, then you can adjust the resistor on the LED to make it brighter. However IME only a few pedals respond like this, most are a bit dim but OK.

Now why does running two ACA pedals off of one daisy chain work - again if you share power and grounds (by connecting a cable) between two ACA pedals, the resistor/diode is effectively bypassed, so you can use a PSA adapter (or any modern 9V) and both pedals will work fine. However, they're like siamese (conjoined) twins - unplug one (either power or signal) and the other won't work. BOTH must be daisy chained together (and connected together or to other pedals sharing the same ground) to work.

0dBVU · November 29, 2005, 08:53:13 PM

Thanks CD! I'll mod the two old CE-2's tonite and report back

0dBVU · November 30, 2005, 12:24:39 AM

I mod'd the two CE-2's and an HF-2 and they all came out perfect... bright LED on all of em. Thanks for the info!

czech-one-2 · February 14, 2011, 04:49:52 AM

Quote from: cd on August 09, 2005, 10:43:35 AM
I would not remove any parts. There's a blue wire that goes from the PCB to the power jack - cut/unsolder this (on the power jack end) and tape it off. There's a yellow wire that goes from the input jack to the PCB - unsolder the wire from the PCB end and solder it to where the blue wire was on the power jack. Done.

Didnt work on my CS-2

czech-one-2 · February 14, 2011, 05:00:50 AM

Quote from: TheBigMan on August 09, 2005, 10:04:33 AM
In the CS-2 it's R38 (470 ohms) and D2 (1S2473) that need to be removed and jumpered. Or you can jumper pads 11 and 12 at the end of the board and leave the parts in place.

Jumpering pads 11 and 12 did!

acromarty · February 14, 2011, 08:29:56 AM

30 years I've had my CE-2 and I never realised it should be using a different power supply.

Now I find my CS-2 is the same and I still hadn't noticed.
That will teach me to read the labels more carefully....

czech-one-2 · February 16, 2011, 07:40:54 AM

Quote from: acromarty on February 14, 2011, 08:29:56 AM
30 years I've had my CE-2 and I never realised it should be using a different power supply.

Now I find my CS-2 is the same and I still hadn't noticed.
That will teach me to read the labels more carefully....

Well, you must be using a 9v battery or daisy chaining it right? My CS-2 wouldnt power on at all using a 9v isolated outlet from a BBE Supacharger. The jumper mod solved that issue.

zombiwoof · February 17, 2011, 07:48:42 PM

I have an ACA adapter, I just use it to power my ACA Boss effects. I didn't want to mod my vintage Boss effects. By the way, the unregulated ACA adapter measures 14.2 volts output when not connected to a pedal!. So it's not really a "12-volt" source as some claim. They are labeled as being 9 volts, however.

Al

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Boss CS-2 compressor ACA to PSA mod?