I fried my dunlop power brick, possible to fix?

[JKowalski]

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

Look into the LM7812 for changing voltages to 12V. Three terminal IC, shouldn't be too hard to stick onto the board somewhere.

If you don't mind them all being 12V, then you can just find a 12V wall wart instead of the 18V one and use that to power the brick. It looks just like daisy chained high voltage outs (direct from power brick input supply) and a switching step down converter for the 9V outs, which I believe should operate exactly the same with different supply voltages.

[Thomeeque]

 

If you would like to alter voltage of "9V" outputs (all of them) you just tweak R15 and/or R16 to (almost ) anything you like.

V_out = 2.21V * (R16/R15 + 1) (see MAX830 datasheet for details)

Here it's 2.21V * (6.8k/2.2k + 1) = 9.04V

Just be careful about maximal voltage of C14 (which I don't see from any picture), for C1, C2.. etc. it's 25V, so they are safe..

T.

[fs2o]

If you would like to alter voltage of "9V" outputs (all of them) you just tweak R15 and/or R16 to (almost ) anything you like.

Thanks a lot that sounds great!!!! I really appreciate it

V_out = 2.21V * (R16/R15 + 1)

Here it's 2.21V * (6.8k/2.2k + 1) = 9.04V

Yep... I see them... so these are the little fellas that are bringing the voltage down to 9.04V...
Ok, sorry if it seems like a real dumb question but, are these resistors (R15 & R16) in series?

Which values should I use for 12V???

Just be careful about maximal voltage of C14 (which I don't see from any picture), for C1, C2.. etc. it's 25V, so they are safe..

I just checked it out and C14 is: 470uf 25V... all the other caps for the outputs (C1 - C10) are 100uf 25V (like you said).

Thanks a lot!!!

Plus, I did just check using a 12VDC external adapter and yes I get 12V from the previous 18V outputs... and the 9V outputs remain giving out a voltage of 9V... so that works out...

The issue is, I'd need an external 12VDC adapter that would be the same size as the dunlop 18V and has a current of 1.000mA... the 12V one that I used for testing is only 300mA...

To make myself clear... I'd need the adapter to be small because the power supply will go under my pedal board (which is an angled platform). The original dunlop 18V adapter fits under there fine...

I need 12V outputs because I have 3 pedals that run on 12V. However, their consumption is 300mA each.

Anyways, I'll read some more on the info you guys gave me... and I'll also write down a list of all components on the DC Brick PCB with their corresponding values...

I really appreciate all the time and answers from you guys... I always like to know how things work and electronics is a passion I have discovered but still have lots to learn... thanks for helping out on that journey...

regards from Brazil

[Thomeeque]

Ok, sorry if it seems like a real dumb question but, are these resistors (R15 & R16) in series?

Check schemo at page 5 of MAX830 datasheet.

Which values should I use for 12V???

Easiest (less destructive) would be to solder 5k1 resistor over (in parallel with) R15 - this way you will get Vout = 11.99V. You can solder one pole of this resistor to the R15+R16 junction and second to the ground anywhere nearby (e.g. to the anode /left node/ of that huge diode above MAX830 IC).

T.

[JKowalski]

Plus, I did just check using a 12VDC external adapter and yes I get 12V from the previous 18V outputs... and the 9V outputs remain giving out a voltage of 9V... so that works out...

The issue is, I'd need an external 12VDC adapter that would be the same size as the dunlop 18V and has a current of 1.000mA... the 12V one that I used for testing is only 300mA...

To make myself clear... I'd need the adapter to be small because the power supply will go under my pedal board (which is an angled platform). The original dunlop 18V adapter fits under there fine...

I need 12V outputs because I have 3 pedals that run on 12V. However, their consumption is 300mA each.

Check out your local thrift store - they typically have a rack or something full of wall warts and power adapters in the electronics section, and they usually cost a buck each. It should be no problem finding a 12 volt 1 A one!

[fs2o]

Thanks guys!!!!

I will look up the 12VDC 1A adapter solution...

But I'm also very interested in the mod solution too... What can I say I'm a born tinkerer... it's a curse and I'm sure I can find a bunch of people here that relate to that...

anyways, the DC brick is not too complicated and just checking out the MAXIM scheme really helped out...

So, I was just wondering: how is it that (as per user's manual) the dc brick 9V outlets can only provide 375mA in total and the 18V outlets can go up 625mA. It looks like the the 18V 1A input, goes straight through to the 18Vouts... what is that limits the 9V outs to 375mA and the others to 625mA???

I just opened up my T-rex fuel tank Jr and it seems like a much more interesting an reliable design... it has 5 isolated 9V 120mA outputs... and the transformer's inside the box (no external adapters)...

I've taken some pics as well and I'll post them soon in case anyone's interested in it...

The reason I'm so full of power supply questions is that I have a good amount of pedals and some are very specific in terms of power...

here's a list:

eventide pitchfactor - requires 600mA 9V and it must not share ground with any other pedal connection or I get hum
TC electronics nova modulator - requires 300mA 12V... it can run at 9V but needs 300mA just the same and loses some headroom.
Another Nova TC pedal soon to arrive - same as above
MusicomLab EFXII - requires 300mA 12V (center positive)
Barber Burn Unit EQ - requires little current and runs on 9V up to 18V... I do prefer it on 18V though
t-rex reptile - requires 135mA 9V or 12V... I do like it on 12V too though

Then I have some other simple pedals that can run on 9V...

But in order to power all of these guys... I need a million wall warts and what not.. which I really hate... So I'm looking for solutions on how to power them...

anyways, making a trip to hardware store... I'll be back with some pics... thanks

[fs2o]

Pics of the T-Rex Fuel Tank Jr are up: http://s1016.photobucket.com/albums/af289/fs2o/

Parts list:

capacitors:
  - 1000uf 25V (quantity: 5)
  - 22uf 16V (quantity: 5)
  - yellow ones - 104 (quantity: 5)
diodes:
  - LED
  - small transparent diode (can't read it)
resistors:
  - brown black brown gold (quantity: 1)
transistors:
  - 7809A JRC MH023A (quantity: 5)
transformer:
  - blue reads - DT 16846-1 08/17 (quantity: 1)
others:
  - fuse reads: LFT50mAL250VP (quantity: 1)
  - RB154A V806 (quantity: 5)

[JKowalski]

Pics of the T-Rex Fuel Tank Jr are up: http://s1016.photobucket.com/albums/af289/fs2o/

Parts list:

capacitors:
 - 1000uf 25V (quantity: 5)
 - 22uf 16V (quantity: 5)
 - yellow ones - 104 (quantity: 5)
diodes:
 - LED
 - small transparent diode (can't read it)
resistors:
 - brown black brown gold (quantity: 1)
transistors:
 - 7809A JRC MH023A (quantity: 5)
transformer:
 - blue reads - DT 16846-1 08/17 (quantity: 1)
others:
 - fuse reads: LFT50mAL250VP (quantity: 1)
 - RB154A V806 (quantity: 5)

Wow, that is one nice transformer. I wish those could be on the open market for us pedal builders.

Looks like a standard multi winding isolated power supply, no surprises there.

My advice to you is this:


The isolated fuel tank is a much better supply because of it's isolation, and I suggest using that.
Also, I highly doubt that the company makes more then one type of transfomer for their different supplies, and because of that I think the transformer in the Junior is the same as in the juicy lucy, etc. If this is true, then that would mean that you can change any of the 9V out to a 12V out just by switching out the relevant regulator IC. So you could just replace one of the 7809 with a 7812 and you would get a nice 12v out instead.

To make sure, you need to measure the voltage on the input of one of the regulator pins. I assume you have a voltmeter handy? Just be sure to watch out for where the line voltage comes in, keep well away from the relevant wires and traces that carry the 120VAC (they should be fairly obvious). You typically want the input of a regulator to be ~4 volts above the output or more. (Well, 2 volts higher would work but I found 4 is a safer bet)

So if I am right, and the transformers are the same it should be something like 15+ volts DC in the input of all the regulator IC's. (input is typically leftmost pin looking at the reg from the front)



As far as the power brick, I think they said that 625ma and 375ma are the limits simply to say that you can have 325 ma coming out of the 9V and 675ma out of the 18V at the same time. It's arbitrary - you could draw an amp from the 18V supply, and nothing from the 9V, or two amps from the 9v supply (depending on the limits of the switchmode supply) and nothing out of the 18V... I'm pretty sure thats the case.





EDIT: Just realized how current hungry your pedals are... Fuel tank can only supply 9V 150ma off of one port. Remember though, the wall adapters are chosen for the pedals with a huge margin, the pedals only use some percentage of what is shown on the wall wart. You'd have to measure the current draw with a voltmeter to know the true current.

So you have the option of 9 or 12 volts isolated 150mA (good for high gain analog circuits) from the fuel tank, and 18V/9V/12V out non isolated high current from the power brick (as I mentioned, adding in a 12v regulator to one of the 18v output pins should be a fairly easy task, you cut one trace, drill three holes, and solder the one part in) You could even find a higher power wall wart for the power brick, say 18V 2A or something, and that would increase your capabilities for the high voltage outs (but the 9V outs are still limited by the switching power supply)

[fs2o]

Hey JKowalski...

Thanks for taking the time!!!

Yes, I agree... the T-rex is awesome and much more reliable than the dc brick... plus it has a fuse... LOL... it seems kindda stupid and basic but I've learned to never underestimate a simple, cheap fuse... also, if it blows... be glad... it could have been something else that got blown...

that would mean that you can change any of the 9V out to a 12V out just by switching out the relevant regulator IC. So you could just replace one of the 7809 with a 7812 and you would get a nice 12v out instead.

anyways... That was my next question... on how to mod the Fuel Tank Jr to provide 12V... I was wondering if just changing the transistors would have done or if I'd need to swap resistors as well...

I highly doubt that the company makes more then one type of transfomer for their different supplies, and because of that I think the transformer in the Junior is the same as in the juicy lucy, etc

I thought about the same thing. But, like I said, I don't know much about electronics... so the fact that the Fuel Tank JR is a 600mA PSU (5 times 120mA) and the Juicy Lucy is a 1500mA PSU  (5 times 300mA) lead me to think that maybe the transformers were different... but I don't even know if that is the case...

The good thing about the juicy lucy is that you get 300mA per output... so combining two of them with a parallel cable.. you get 600mA of 12V power... which is great for hungry pedals like you said...

Just realized how current hungry your pedals are

Exactly... hence all the fuss about these power supplies...

Remember though, the wall adapters are chosen for the pedals with a huge margin, the pedals only use some percentage of what is shown on the wall wart. You'd have to measure the current draw with a voltmeter to know the true current.

Yep... the current draw for each pedal I wrote on the other post is already the actual draw... the info came from contacting other users and the manufacturers themselves... it's crazy, here:

eventide pitchfactor - 9VDC 1200mA per user manual /// actual draw= 600mA 9VDC
                               furthermore, the eventide's stock power supply is 9VDC 1200mA unregulated which in reality measures 14.2VDC and somewhere around 12.5VDC when the pedal is active... so some folk are actually powering theirs with a 12V (such as the juicy lucy using 2 outputs in parallel)

TC nova - 12VDC 300mA per manual /// actual draw around 300mA but can be either 9VDC or 12VDC

MusicomLab EFXII - 12VDC 400mA per manual /// actual draw around 300mA... the previous version of the pedal could be powered with either 9V or 12V... but the new version's manual says 12V only... I really don't know for sure about this one, it is korean made but indeed a great unit!!!!! Best controller I've ever had...

The T-rex Reptile has an actual draw of 135mA...

all the other ones are really not that "hungry"... LOL...

but the issue is, the pitchfactor needs to be powered separately (no common ground) or through isolated outputs on a PSU otherwise the hum is terrible... the other 12V pedals draw considerable amount of current, so they need to have good supplies... specially the EFXII... can't have it fail on me live cause all other pedals go trough it...

so, as of now, I have 4 different PSUs to power everything... which is ridiculous... the eventide is fed by a 1spot PSU (the original adapter is too big for my pedalboard)... the EFXII is powered with its original PSU (about the same size as the 1spot)... the nova is also fed by a DC brick and all other pedals by another DC brick...

I need to slim that down... 1 PSU for everything...  or 2 at the most... the voodoo lab pedal power is too tall to go under my pedalboard... the T-rex jr and the dc bricks are perfect fits... plus, I have 2 dc bricks and one of them has a couple burnt components so I would not mind messing with it... it's be great if I could make the DC brick have 2 isolated sections... 1 with 9V and the other 12V with 500mA each... than I'd be in business... LOL

PS- could not find the 12V 1A adapter (same size as the original dc brick)... you would not believe how hard it is to find these things in Brazil... music related equipment is just hard to get... frustrating!!!!!

anyhow... thanks a lot for the input and the help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Fred

[fs2o]

Hey guys,

Just wanted to let you know, I should have Juicy Lucy coming in the next few weeks and I'll post some pics here when it arrives...

I've always looked for pics of the inside of these things but can never find any, so I'll post when they arrive...

so, back to my "problem"...

think I've decided what would be best for powering my pedals...

a modded dc brick (that will give out 12v and 9v - instead of the usual 18v/9v)... and a 1spot to power up de eventide...

so I'll have only 2PSUs for everything... when the juicy lucy arrives, I'll switch to: juicy lucy + fuel tank jr

When gigging all the time I find it doesn't hurt to have a spare setup when possible... so the 1spot and dc brick will be my back up


anyways, in order to achieve any of the setups above, a small mod should be required... I'll refer to them setup 1 and 2 as follows:

setup 1 - DC Brick + 1spot
setup 2 - juicy lucy + jr

in setup 1, the dc brick will be modded to 12v instead of 18v
in setup 2, the juicy lucy will be modded on 2 outputs to give out 9v instead of 12v... these 2 outs combined will provide 600mA of 9V to power up the eventide.

Now, here's the tricky thing... I'd like perform these mods in a less invasive way: by that I mean, making a small external power attenuator in one of those tiny metal enclosures (like the catalinbread pedals or even smaller)... so that I wouldn't have to mess with the inside guts and original circuit.

I'd need something to bring 18V  625mA down to 12V (on the dc brick) – the external adapter would be great, but I can't seem to find the darn thing with 12V (1A or more) in a small/slim enough size
And 12V  600mA down to 9V (on the juicy lucy)
The idea is to follow something like this: http://www.instructables.com/id/5V-breadboard-mini-PSU
Any thoughts on this? thanks

[Nocher]

Hey there everyone, I have a DC Power Brick too, and I fried it the other night mid-gig. I opened it up and it looks like part of the board is toasted between the power input and D8. Here's a link to some pictures, you should be able to clearly see what I'm talking about.



Any advice on how to fix this? I've never tried anything quite this small/delicate, but I'm fairly handy with a soldering iron and I figured I'd take a crack at it rather than drop 100 bones on a new power supply. Also, I'm not sure how to test to see if any other components were fried, or if it's just that strip after the power supply. Any input would be greatly appreciated, thanks in advance!

[Nocher]

Sorry, the picture link didn't post the first time.




The rest of them are here - http://s618.photobucket.com/albums/tt262/Nocher83/DC%20Brick/ , but those should suffice to show the problem.

[marcoaam]

Hello everyone!

My DC Brick is also showing a problem. I opened it and the D8 diode seems to be exploded. Could anybody tell me what kind of diode is that?

Thanks in advance!

And sorry about my rusty English...

Marco  (Rio de Janeiro, Brazil)

[rousejeremy]

Looks like a 1N4001

[marcoaam]

Thanks, man!