Re: [Harp-L] Did I fry my ART Tube MP pre-amp wall wart

["Bob Laughlin" <rlaughlin@xxxxxxxxxxxx>]

Okay,,my turn,,haha

I've been an electronics enthusiast, via amateur radio, AND an electrician
by trade, for 25 or so years, so, on a limited basis I know what I'm about
to say:

First, since the power supply doesn't work on the ART Tube MP pre-amp
anymore, you probably did damage to the power supply, rather than the
pre-amp.

Before plugging, or even unplugging the power supply from this or that, it
should be unplugged from the wall, ideally. If, while plugging or unplugging
these things into this or that, the tip shorts to the shell (of the 9V plug
end), it could possibly damage the windings of the transformer, making it
unusable. That's probably what happened. A transformer has two sets of
"windings", or "coils", one in proximity to the other, transferring
electrical power, through the principle of inductance
(http://en.wikipedia.org/wiki/Inductance), to the other coil, e.g.,,from the
wall plug end to the 9V plug end. During this transfer, the voltage is
changed, to make it applicable to whatever you're using,,the delay pedal,
the pre-amp, etc.

Also, before trying this, after unplugging from the wall, you should have
gotten a hint from the fact that the plug didn't fit, to simply give up the
attempt. When something doesn't fit, physically, it usually won't work,
electrically, and may damage whatever you're working with.

Next, the voltage specs are generally written on the power supply, but this
doesn't account for polarity, i.e.,,which is positive and negative, the tip,
or the shell, on the plug. This could be tested with a small voltage tester,
known as a "VOM" (Volt-Ohm-Milliameter), or "Multimeter", if you know how to
use one. I'm not entirely sure whether the tip is always positive, or the
shell, or whether there are variations. In my years of electrical work, you
ALWAYS find variations, so caution is paramount, if you wish to avoid a
catastrophe.

But still, the fact that the plug didn't fit,,that's the big one. "If it
don't fit, you must acquit,," (Oh wait,,that was the "OJ" trial,,). If it
don't fit, just quit, or maybe your equipment will go to sh**. NEVER force
things. If they don't SEEM made for each other, they probably aren't.

As was posted already, you can probably find a "universal power supply" at a
local "Radio Shack" store, or electronics supply house. You have to be clear
what voltage you're getting from the wall socket, 120, or 230, or
whatever,,and what voltage you wish to derive from the power adapter,,9V, or
whatever. That's crucial. Then, you have to have the right plugs, on the
wall end, AND on the equipment end. The universal supply often comes with a
multi-ended adapter, with which one may find the right plug to go to the
equipment.

Once having worked out these details,,the voltages, and the plugs, there's
still the matter of polarity.

It's always best just to get a replacement supply from the company that
makes the equipment.

BL



----- Original Message ----- 
From: "M. N." <mnessmith@xxxxxxxxxxx>
To: "list harp" <harp-l@xxxxxxxxxx>
Sent: Sunday, March 30, 2008 12:43 PM
Subject: [Harp-L] Did I fry my ART Tube MP pre-amp wall wart


>
> Tonight I was monkeying around with my new ART Tube MP pre-amp, running it
into my little tube amp and loving the sound. I decided to switch gears and
try out my BOSS Digital Delay DD-3, which I haven't used in awhile. It
didn't have a battery in it and, rather than scrounging around to find a 9v
battery, I just unplugged the power cord for my ART Tube MP and plugged it
into the BOSS Digital Delay DD-3. The plug itself didn't quite fit (is too
long), so I pulled it out and popped it back into the Art Tube MP pre-amp.
Result? No lights on the ART Tube MP, and no sound. No nothin.
>
> I'm afraid I did something really dumb and am now going to pay a stupid
tax.
>
> Here's what the ART Tube MP pre-amp's wall wart says: INPUT: 230V~50Hz,
and under that: OUTPUT: 9V~1000Ma. (I am in Europe, btw, that's why the
230V.)
>
> Here's what the sticker on the back of the BOSS Digital Delay DD-3 says:
230V .... PSA-230 (9V DC)
>
> Any guesses on what this Einstein did?
>
> MN
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