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Kevin glenville
06-11-2015, 08:24 PM
Hi all I'm after a bit of help, I work in a school and they have a denon mc 3000 in the music dept. Unfortunately a student plugged a 18 v power supply into it and killed it.
I have removed the top but can't see any visible damage.
Appreciate any advice

Excalibur
06-11-2015, 08:50 PM
Ouch! Let's hope one of the technocrats comes by soon. Sorry to be a prophet of doom, but these things don't often end happily. :(

Oh for the old days, when you might get away with fifty pence worth of fuse.

yourdj
06-11-2015, 09:32 PM
Is it a Demon, Denton or Denon (http://denondj.com/products/view/mc3000) ;)
Cant really help you unfortunately, but I would assume a new power management unit would be required. Could be a cheap fix if none of the rest is damaged.

Excalibur
06-11-2015, 09:43 PM
Is it a Demon, Denton or Denon (http://denondj.com/products/view/mc3000) ;)
Cant really help you unfortunately, but I would assume a new power management unit would be required. Could be a cheap fix if none of the rest is damaged.

Says Denon on my screen, Toby. :confused:

Just goes to show the importance of keeping the correct power supplies with equipment. Labelling them is an excellent idea, too.

ukpartydj
06-11-2015, 10:06 PM
Do controllers have fuses? Would be the first thing I'd check!

yourdj
06-11-2015, 10:20 PM
Do controllers have fuses? Would be the first thing I'd check!

I was going to suggest that, but did not know if they were fused for low voltage. Someone else is probably much better to advise. My bet would be one of the power management chips/transistors is blown or something?

Nakatomi
07-11-2015, 02:20 AM
Chances are the original psu isn't far short of 18 volts (I dunno, I don't own one) so maybe it wasn't extra volts wot done it. Maybe the 18v power supply was a different polarity. If that is the case it'll likely be time to get a new controller or send that one to the fixer.

First thing I'd look for is the power supply socket inside the unit. Look around & see if you can trace where the centre pin goes. Connected to that will probably be a component known as an inductor. It might be a Diddy little thing about 3mm long by 1.5mm wide which sits (electrically) between the centre pin of the socket and the internal power supply. If you have a multimeter, check its resistance. It may have gone pop. A good inductor will have a low resistance, maybe a couple of hundred ohms.

That's square one. There's unlikely to be any kind of fuse in there but it'd be worth following the path of the centre pin of the socket & see where it leads.

In my experience if an inductor has gone pop because the power supply was reversed you could be ok to replace or bridge across it with a small piece of wire.
Soldering is required here.

If however the original Denon power supply puts out a lesser voltage, say 5 volts .... Then the poor mc3000 will likely need a full board replacement. It'd be cheaper to buy a new controller no doubt.

Excalibur
07-11-2015, 10:05 AM
Chances are the original psu isn't far short of 18 volts

According to the manual, twelve.


If however the original Denon power supply puts out a lesser voltage, say 5 volts .... Then the poor mc3000 will likely need a full board replacement. It'd be cheaper to buy a new controller no doubt.

From what I've heard, items operating from the standard USB voltage really do not like over voltage at all. Laptop power supplies thus are dangerous things, so label and keep separate, I suggest.

Nakatomi
07-11-2015, 10:28 AM
According to the manual, twelve.



From what I've heard, items operating from the standard USB voltage really do not like over voltage at all. Laptop power supplies thus are dangerous things, so label and keep separate, I suggest.

If it's designed for 12 volts then maybe 18V wouldn't have been too bad for it - I suspect that the denon drops the input 12V down to levels it needs inside. If anything is meant to work directly from the 12 volt side, then I don't think it'll have minded 18V.

Check the polarity of the offending power pack.. I really think it's likely the opposite polarity of the Denon one (i.e. centre pin positive on the Denon, centre pin is negative on the wrong supply).

And yes Peter, if you put 18V directly into something that's only designed to run from 5V you will very likely kill it to death.

I don't think the prognosis is a good one for the poor old MC3000.

CRAZY K
07-11-2015, 01:51 PM
According to the manual, twelve.



From what I've heard, items operating from the standard USB voltage really do not like over voltage at all. Laptop power supplies thus are dangerous things, so label and keep separate, I suggest.

Funny you should mention that Peter, I destroyed an old mains driven SEAGATE hard drive by accidentally plugging in a laptop cable---ah well it was time to switch to unpowered hard drive anyway --annoying though as it had done great service and entertained literally thousands of people😩

ALAN
CRAZY K

Kevin glenville
08-11-2015, 05:25 PM
Thanks for the advice guys
Doesn't look good