#1
Hi I have an old school Morley wah pedal looks to be from the 70's, the print has rubbed off the sticker on the back, it is 9v but what would be a safe mA to go for adapter wise? Also is it centre pin polarity?

Is it true that you cant have to much mA, just not enough? Im trying to work it out so I can have 1 adapter for my wah and od pedal.

Thanks.
RG's & Mesa's
#2
I have an old Morley PWA and it draws 9mA, centre negative. They recommend a 300mA supply but that is overkill really. And yes, as long as your supply can supply greater or equal to the current draw you will be fine. It can't be too big, just too small. To give yourself room for error I'd aim for >100mA for the wah.
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Last edited by Cathbard at Sep 11, 2013,
#3
It is true that you can't have enough current, as long as the voltage is right.

If you apply too much voltage (say the double) to a pedal designed to run on a specific voltage, it will draw more current than the ammout it's designed to run on, and chances are it will break.

Some pedals don't, and some pedals have a protection, but unless you're sure you shouldn't try changing the voltage.

Anyway, guitar pedals usually have the - pin in the middle, but not being sure you can try leaving it on and powering one way first, and then another to see what works.
Nothing bad should happen as long as you don't keep the plug in for more than a couple seconds to see if it works.

Analog pedals don't use that much power, so with just two pedals you should be fine with your everyday power adapter.
The worst thing that can happen is that your adapter can't supply enough current, and your pedals don't recieve enough power to work.
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#4
Quote by Spambot_2
It is true that you can't have enough current, as long as the voltage is right.

If you apply too much voltage (say the double) to a pedal designed to run on a specific voltage, it will draw more current than the ammout it's designed to run on, and chances are it will break.

Some pedals don't, and some pedals have a protection, but unless you're sure you shouldn't try changing the voltage.

Anyway, guitar pedals usually have the - pin in the middle, but not being sure you can try leaving it on and powering one way first, and then another to see what works.
Nothing bad should happen as long as you don't keep the plug in for more than a couple seconds to see if it works.


Analog pedals don't use that much power, so with just two pedals you should be fine with your everyday power adapter.
The worst thing that can happen is that your adapter can't supply enough current, and your pedals don't recieve enough power to work.

Old Morleys have diode protection on the power input but it doesn't have a resistor in series so if the supply doesn't have overload protection and you transpose the polarity you could easily blow the supply because the diode is shorting it out. A couple of seconds in electronics is like a decade to a human. In short - don't.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
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Last edited by Cathbard at Sep 11, 2013,
#5
Quote by Cathbard
In short - don't.

I see what you did there!
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#6
cool thanks heaps for the advice. Luckily the part of the sticker relating to the centre pin polarity is still intact, and yes it is centre pin negative. Im going to use a standard 500ma 9v generic power supply for the wah and my o/d pedal (which specifies 300ma). It should be ok to just Y the power cord to power both yeah?
RG's & Mesa's
#7
Yeah, should be fine. I bet the OD doesn't actually draw 300mA.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#8
The Crybaby only draws like .4ma, the Morely probably doesn't draw much more.
Check here : http://stinkfoot.se/power-list/page/2
You might find the current draw of your OD there as well.
Last edited by CodeMonk at Sep 12, 2013,