Update: Boss OC-2 experts: why won't it drop the octave!

[Jazzjames]

Hi all,

I'm looking for someone more technically minded than me to shed some light on an issue I am having with my old Boss OC-2.

It's a Tawanese model, but says "use Boss ACA" adaptor on the side.

It works okay with a 9v battery in it, but with my pedal board (running at 9v or at 12v, my power supply can provide both) it doesn't work properly, and will only create the sub octave if I play really loud, which isn't right.

I've got 3 basses and it's the same with all of them.  Why could this be happening?

 

Thanks!

 

James

Edited February 12, 2019 by Jazzjames

[dannybuoy]

Not sure what is going on there, but these ACA pedals have an oddity about the way they're wired, which is this. You can run them at 9v if the power is daisy chained to another pedal. Don't ask me how, but it's common knowledge and I've seen it in action - plug in a single 9V supply and the LED is dim, hook up a 2nd pedal on the same supply and the LED gets brighter! So if your supply has a splitter/daisy cable, try seeing what happens there.

It should work just fine with an isolated 12V output though so perhaps something is up with your pedal. Is the LED just as bright as when powered by a battery?

[Jazzjames]

2 hours ago, dannybuoy said:

Not sure what is going on there, but these ACA pedals have an oddity about the way they're wired, which is this. You can run them at 9v if the power is daisy chained to another pedal. Don't ask me how, but it's common knowledge and I've seen it in action - plug in a single 9V supply and the LED is dim, hook up a 2nd pedal on the same supply and the LED gets brighter! So if your supply has a splitter/daisy cable, try seeing what happens there.

It should work just fine with an isolated 12V output though so perhaps something is up with your pedal. Is the LED just as bright as when powered by a battery?

Good idea, I’ll try the daisy chaining, thanks!  The LED gets brighter with 12v but still behaves in very glitchy way.  With a battery it tracks nicely and doesn’t misbehave.

[hubrad]

It was (ahem!) some years ago, but I had some Boss pedal that just clashed with other pedals. Fine on battery, but noisy as you like when in a FX box all on the same PSU. I spoke to the Boss folks, who said that ground wasn't actually 0 Volts, unlike pretty much everything else available at the time. I wonder if it's one of those?

[Sibob]

I wonder if it's a fault. I have OC-2s from early 80's all the way to 2000's and never had any issues running any of them off single Boss adapter, larger board power (daisy chains etc) or battery. I'll triple check my oldest OC-2 tonight with a Boss PSA for you. 
I did have an old VB-2 (Vibrato) that was perfectly fine on battery and board power, but wouldn't work properly on a modern Boss adapter.

Will come back to this later.

Si

[Jazzjames]

For anyone who may read this thread at a later date, I found a permanent solution.  This works for any Boss ACA 12v pedal, not just the OC-2.

 

I followed the information here:

http://stinkfoot.se/archives/1019

 

For the OC-2:  Remove Diode 3 and resistor 17, and solder in wires in the same locations.  This means the pedal will now run properly on 9v regular power supplies.  You can see D3 and R17 sitting next to each other on the schematics attached.

 

My pedal now has a bright LED light and operates in a much better way than before.  The tone is fat!  I realise that these pedals are getting a bit more valuable, but mine is from Taiwan, and I bought it for 20€ so I doubt I'll ever sell it anyway.

Thanks for everyone's help.