What polarity is the plugpack on Boss pedals?

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Hi,
Does anyone know what the polarity of the power plug on Boss pedals? (Boss rc-2) Is it positive in the center pin or negative? I have a 9v adaptor that I want to use but I dont know which way to solder the plug on.
I measured the voltage on the center pin with the battery connected and it was negative, with positive to chassis, but I want to be sure in case I blow up my $300 pedal.
Does anyone have the official Boss adaptor to measure?
 
...in case I blow up my $300 pedal.....

Simple mod to prevent the "blow up"... Wire a diode across the power jack. If the correct power supply is connected the diode is reverse biased and does nothing, just like it's not there. But if the wrong polarity supply is plugged in the diode acts like a short circuit and the fuse in the power supply blows.

A slightly more complex mod is to also but a fuse in the pedal in series with the power input jack, now when/if the diode conducts the fuse inside the pedal blows.

This is a very simply safety device that can be used with any DC powered device to protect from reverse power connections. It is so simple and inexpensive that it is common. You might check. Many devices have this already built-in. If it is then don't worry about blowing up anything other then a fuse.
 
Enzo said:
Or wire a small bridge at the power entry - then either polarity power supply will work.


No, the diodes in the bridge will drop the voltage by as much as 1.4 volts. That could be enough to make a three terminal regulator "drop out" The bridge idea is good if you are using a 12V power supply and then dropping down to 9V with a regulator.
 
Nigel Goodwin said:
Cheap wallwarts are unregulated, a pedal such as this one is almost certainly designed to run from an un-regulated wallwart (as they are cheaper).


This whole thread has been about guessing. The best thing is to check a schematic. Here is one for the DS-1.
http://www.godiksennet.com/images/sch/DS1PG2.jpg
It is the simplest one and makes a good example. Notice a few things

1) There is a diode and 470R resistor in series with the input jack. So go ahead and plug in a reversed power supply. It will not work but nothing will blow up either. Like I wrote above - this is so easy to do that most devices have this minimum level of protection built-in. But you have to check. Some companies would jump at the chance to save 2 cents

2) The ciruit is completely unregulated and would work fine at higher voltage, although I doubt the other Boss pedals are unregulated as they might be using some ICs that require it.


You can get the schematic for almost any Boss pedel just by searching Google
 
Hi,
The plugpack I am using is one of those multi voltage adaptors with 3-4.5-6-7.5-9-12v so I thought it would be regulated, but when I measured it on the 9v setting, it measured 10.6 volts. I just put it on the 7.5v setting and it measured 9.6v and it works fine, it has not blown up yet.
 
Those are not regulated, just adjustable.

Wall warts are rated for a voltage and an output current. The voltage should appear when the rated current is being drawn. If you draw 100ma from a 800ma wall wart, the voltage will indeed read very high.

ChrisA - speaking only for myself, I wasn't guessing. I am aware that the Boss power adaptors are negative center from experience. I own and operate a pro audio service facility.

I would add that the real Boss wall warts, while not regulated, are better filtered than the average wall wart. SO if you replace theirs with something from Radio Shack, you MAY wind up with more hum than with the original wart.

Many many Boss pedals are protected by a diode across the incoming power - often an 11v zener, but also just a plain rectifier. Reverse polarity (and excessive voltage) applied is shunted across by this diode, which usually shorts out. the shorted diode then prevents any other damage. Replacing the shorted diode is one of the most common Boss pedal repairs.
 
Hi. I have a question somewhat related to this topic...

My friend gave me a Taiwan-made DS-1 that was "blown" by someone using wrong polarity wall wart. I opened it up. The D1 was broken, cut in half. Then I forgot the pedal in a box, until I recently bought a pile of components for other effect projects. Since the pile included a couple of 1N4007 diodes, and my girlfriend is in need of a distortion pedal, the DS-1 is now on my desk. Just got the diode (originally 1N4004) replaced, but the thing still don't work. Does it make a difference in this case if the diode has a different voltage rating? I thought it doesn't...

Referring to the last part of the previous message, shouldn't the diode be the only part to break in the case of reverse polarity wall wart used? The pedal went silent instantly, so I was told...
 
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