I fried my dunlop power brick, possible to fix?

[clorinde]

--------------------------------------------------------------------------------

Hi people,

Something terrible has happened... Yes, I accidentally connect a 24v power adapter to my dunlop power brick (which accept 18V) so I fried it... 


I niticed the 18v outs are still working but the led is dead and so the 9v outs.
Can I get it fixed or I can just bin it?
I heard it might be the capacitors that need to be replaced but I'm no expert.

Any advice?

[bancika]

opet it up, it shouldn't be that hard to find the fried component

[clorinde]

By the way, I opened it but all the components look ok...

[petemoore]

  Your'e into high voltage...you should know what you're doing before opening it.
 Every component in it can be tested.
 The caps are probably new-ish in terms of cap-life, how old is it...probably not old enough for caps to go...the sequence of working / event / stopped working doesn't lend itself to cap-life-end probabilities.
 I would guess there is 1 primary [which is getting AC input because the 18v works] and however many secondary taps there are [18v and 9v ?].
 Take a look at the Spyder to see what it takes to make a power supply.
   http://geofex.com/Article_Folders/Power-supplies/powersup.htm
 Here's some junk I read...after looking for reliable info...
 I use a Voodoo Labs Pedal Power 2 Plus. It has 8 isolated 9 volt outputs. The circuit isolation feature allows me to power a positive ground Fuzz pedal from the same supply as my other negative ground pedals. You can't do that with a power brick or 1-spot, etc. The PP2+ is dead silent and works great. It has some other cool features but I won't go into all of that.
 This blurb, combined with the fact that all the 9v's went south simultaneously, leads me to 'assume that the outputs are not isolated, that 9v is made once and the outputs are paralleled.

[petemoore]

  Someone wrote that there are schematics all over for it, I didn't find one yet.
 Without the schematic...understanding of AC to DC conversion, DC regulation, and basic routing of the Brick circuit could suffice.
  So without a schematic, assuming..assumptions are somewhat dis-assumptive...
  Take one output of the Spyder, notice there's an AC tap which feeds a diode bridge, filter caps that 'top up' and reduce the amplitude of the pulse ripples from the diode bridge's pulsey-feed, a regulator to make a steady/solid 9vdc, then a bit of further filtering, there's at least and probably one supply like this on the 9vdc portion of the DC brick.  
 

[clorinde]

The dunlop power brick is new. It uses a separate power adapter of 18v. Instead of this I plugged a 24v adapter by mistake, and that's it, gone. £110 Opening the thing without the power adapter plugged in is pretty safe. I think I'll just buy another one I guess... 

[petemoore]

 Multiple isolated outputs in a box is nice, then you have individual secondary taps and regulators and filtering for each output, if one gets connected to an adapter and fries, you have however many other isolated 9vdc outputs left working.
  Also nice because - and + supply effects are..isolated.
  Using separate/isolated, floating 9vdc supplies..disconnects PS grounds, preventing ground loops and any associated hum.
  The Spyder works like this.

[anchovie]

By the way, I opened it but all the components look ok...

When a component blows, it doesn't necessarily mean it will look like it exploded!

The Dunlop power adaptor is 18V DC regulated, so I reckon the reason the 18V outputs on the brick still work is because it passes straight through. Can you post a good picture of the inside of the unit, so we can see what it's using to make the 9V for the other outputs?

[slacker]

Was the 24 volt adaptor AC or DC? If it was DC was it the same polarity as the 18 volt one.
I would be surprised if plugging a 24 volt DC supply of the correct polarity would damage anything. If it was the wrong polarity or an AC supply it could cause some damage. Shouldn't be too hard to fix though.

[petemoore]

  Yea, I skipped following [because I coudln't follow] the part about how 24v connected to the brick, assumed there was a DC plug handy that looked like it fell out so was plugged in...turns out it went to an adapter not a circuit for supply.
  And decided to assume the 9v outs are all from 1 actual supply [from the fact they all dropped out simultaneously + what somebody wrote].
  There's really nothing new in there, but it could be wired up this way or that, so, without a schematic it's kinda maybe hit, or miss with the suggestions.
  You can tell if the outputs are paralleled..set the DMM to beep mode and test if the outputs contacts are sharing/common.

[ocg]

can you post some pics of the guts?

[JKowalski]

Is there any leakage of fluids on the top of any electrolytics? Or a bulging top? Sometimes caps can die but show no visible sign of it as well...

[petemoore]

  What voltage do you measure on the 9v outlets ?
 See if the 'small' secondary tap feeds AC to the 9v recitfication, diode bridge.
 Remove power cord, and test for a short across that secondary.
  Lifting a lead from that secondary from the diode bridge and re-testing both would reveal if there are any shorting conditions in the mentioned portions, if there's AC out of the small secondary.
  If the secondary is good, then, you can always add the DC recto-bridge and filter/regulator, say..in a pedal if there's no room to fix/cram another one in the unit.

[anchovie]

Pete, I don't think there's any AC or rectification in this. The user manual states that it takes regulated 18V DC in and provides outputs of 18V DC (which is working, so it must simply be split from the PSU to the output sockets) and 9V DC (which is not working, so something in the circuit that regulates the 18V down to 9V has blown). The LED is obviously being fed from the 9V output, hence it does not illuminate.

Clorinde - we need a gutshot. This is as much speculation as can be made without knowing exactly what's in there.

[Paul Marossy]

I have a hunch that there is a 9V voltage regulator inside the unit that died as a result of being supplied a higher voltage than its input allows. In other words, the input voltage exceeded the maximum allowed by the voltage regulator.

There's no AC voltage in this power supply, so it's not dangerous to work on.

[fs2o]

Hey guys... I just ran into this thread...

I'm not an expert in electronics but I am very interested in it...

I do own a couple of Dunlop DC bricks... I can provide some more info on them (pics too) and then maybe you guys can help me mod one of mine too...

anyways,

the DC brick does NOT have isolated outputs...

there is external an adapter (wall wart) that is 18VDC center negative that provides a current of 1000 mA
the adapter is then plugged into the dc brick which has a total of 10 outputs (all center negative)... 7 of them are 9VDC and the other 3 are 18VDC...
the DC brick is regulated... I measured the current on all of the outputs on mine and they are pretty accurate...
further more... the 9VDC section (the seven 9V outputs) can provide a maximum of 375mA total....
and the 18VDC section (three 18V outputs) can provide a maximum of 625mA total....
I also checked with a multimeter and all of the outputs share a common ground...

At 1st I thought that the 18v and 9v sections were isolated from one another, but they're not.

I opened up my DC brick and the pcb layout is fairly simple (one sided PCB) and you can clearly see the common ground...

One of my DC bricks has had 2 of its 18V outputs burn out... one of them measures 4.4V now and the other 18V but does not properly power up any pedals.

I purchased the unit used and it came that way... I assume the previous owner plugged the external adapter in the wrong jack but I'm not sure, anyway, you can see that there is 1 resistor that did indeed burn.

What I'd like to know is wether it's possible to isolate the 18V section from the 9V and change the voltage to 12V... by that I mean, changing either the 18VDC section to 12VDC or the 9VDC section to 12VDC...

Anyways, thanks in advance guys!!!!

PS- How do I post pics here? do I have to upload them to the web first? can't I just upload them from my PC?

[Thomeeque]

I do own a couple of Dunlop DC bricks... I can provide some more info on them (pics too)

Yes, please

What I'd like to know is wether it's possible to isolate the 18V section from the 9V..

Only with another external adapter plugged in - with one only it's almost impossible (doable, but way too complicated)

PS- How do I post pics here? do I have to upload them to the web first? can't I just upload them from my PC?

You can only link images (already placed somewhere on the web) here.

T.

[fs2o]

OK,

I uploaded a bunch of pics on Photobucket...

Think it might just be easier to post the link here...

Please let me know if you can actually view the album (12 pics)

PS- guess I was wrong about it being a one-sided PCB... it looks like both sides have traces but still, it seems simple enough...



http://s1016.photobucket.com/albums/af289/fs2o/

[fs2o]

What I'd like to know is wether it's possible to isolate the 18V section from the 9V..

Only with another external adapter plugged in - with one only it's almost impossible (doable, but way too complicated)

yeah... I'd like to do it with one external power supply only... (or 1 transformer I guess)... just like the T-rex power supplies... or voodoo labs...

Ok... if it is indeed to hard to do... how about just changing the output voltage to 12VDC on one of the sections... doable? should be easy enough as swaping some resistors.. right??? LOL hope so

[rustypinto]

I know we all love to tinker here, but unless you want to mod or figure out how that supply works, i'd try to return it for a new one.