Why didn't this replacement AC adapter work?

jonniebbad · Jul 12, 2014

Hello there. Signed up here looking for a place that knows about electronics because I really don't know much. I own a Roland ME-25 Multi-Effects Guitar Pedal.

This is the UNIT specs:

This is the SPECS for the AC Adapter you're supposed to buy separately:

And this is a replacement AC Adapter I had on hand (figured it would work since both are 9V adapters)

Of course, the replacement didn't work. The unit didn't even power on. Did the replacement not give it enough power or too much power? I believe I read this guitar pedal has a voltage overload meter and the device will flash on for a second and shut off if that happens to protect itself (I personally didn't notice that). Anyway, only posting this here because I can't make sense of any of these voltage's, wattage's, etc... numbers.

Appreciate the help. Thanks

NiHaoMike · Jul 12, 2014

Reverse polarity and (probably) not enough current..

caddi daddi · Jul 12, 2014

just carry the one that came with it to the store with you and you might get lucky and find some one that knows a little about it.

you need one with .5 amp output, - (neg) on the inside and +(pos) on the outside.

WhitehawkEQ · Jul 13, 2014

jonniebbad said:
Hello there. Signed up here looking for a place that knows about electronics because I really don't know much. I own a Roland ME-25 Multi-Effects Guitar Pedal.

This is the UNIT specs:

This is the SPECS for the AC Adapter you're supposed to buy separately:

And this is a replacement AC Adapter I had on hand (figured it would work since both are 9V adapters)

Of course, the replacement didn't work. The unit didn't even power on. Did the replacement not give it enough power or too much power? I believe I read this guitar pedal has a voltage overload meter and the device will flash on for a second and shut off if that happens to protect itself (I personally didn't notice that). Anyway, only posting this here because I can't make sense of any of these voltage's, wattage's, etc... numbers.

Appreciate the help. Thanks

The Boss unit has the center contact as "-", the other unit, the center contact is "+", both units have enough current at 9V, just need to make sure you have the right polarity.

bob4933 · Jul 13, 2014

Well, if you can't take it back, just cut the wire and flip it.

NiHaoMike · Jul 13, 2014

There's probably a good reason the recommended adapter is 500mA. Maybe the average draw is 140mA but the peak is much more than that.

jonniebbad · Jul 13, 2014

Holy crap. I didn't even know there could be a polarity difference in AC adapters. Is that equivalent to putting in a AA battery flipped the wrong way?

If so, could have I damaged the unit in any way using that replacement adapter? Thanks for all the help guys!

Bobnova · Jul 13, 2014

It could have killed it completely, yes. Reverse polarity will kill things if they aren't properly protected.
The key is, those are AC-DC adapters that put out DC.
If they put out AC it wouldn't matter nearly so much.

jonniebbad · Jul 19, 2014

Bobnova said:
It could have killed it completely, yes. Reverse polarity will kill things if they aren't properly protected.
The key is, those are AC-DC adapters that put out DC.
If they put out AC it wouldn't matter nearly so much.

I have the original adapter now and it works fine. As I said before, it seems this device has a voltage meter as others have mistakenly used the wrong adapters that gave off more voltage and the device would flash (turn on for a second) and then turn off. Though I'm not sure if this would protect from the mistake I made...

I guess my only concern would be is it possible I damaged any components in the unit even though it works fine? Are modern day electronic devices (I think this was made in 2010) known to have components built in to protect from stupid people like myself (lol) who used the wrong adapter?

Also oddly enough (maybe I'm just lost here), but above the power adapter input, it says "DC in" on the device itself.

Bobnova · Jul 19, 2014

If it works it works, it must have a protection diode.

That's a DC output power brick and a DC device, so that makes sense.

You could try cutting the AC-DC adapters cable and re-wiring to swap pin positive to the pin negative that the device wants.

Why didn't this replacement AC adapter work?

jonniebbad

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