Help needed for power supply wall wart replacement

jpttaylorjpttaylor Frets: 458
edited September 2017 in FX
On the recommendation of the internet as a whole and a few people on here, I bought a Vitoos DC-8 a few weeks ago that shipped from China incredibly quickly. Sadly, it didn't work out of the box and the website responsible have been incredibly slow, unresponsive and annoying. They insisted in the (limited) correspondence I've had with them that it was the wall wart and a new one is much cheaper than taking it to my local tech, so I'm hoping that they're right this once.

Before I order one, what things do I need to look out for? I've gathered from the actual plug that it outputs 12 volts at 2amps and the tip is centre negative, Boss style (I think). Also, does anyone know which places online would sell just a wall wart rather than a whole replacement power supply?

Many thanks






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Comments

  • prowlaprowla Frets: 4896
    12V DC power supplies seem to be quite plentiful; some printers use them, some keyboards (Yamaha).
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  • ecc83ecc83 Frets: 1591

    http://cpc.farnell.com/stontronics/t6355st/ac-dc-power-supply-12v-2a-vi/dp/PW04224?mckv=s2D8F4QFD_dc|pcrid|72935558297|kword||match||plid||pid|PW04224|&CMP=KNC-GUK-CPC-GEN-SHOPPING-STONTRONICS-Power_Supplies-PW04224

    I would suggest you buy from a reputable source, gash supplies from 'Zon' can ne noisy. Maplin also have the pt# R50 CW . 3amps but that will not matter.  You may need to adapt/re-wire to get the correct polarity.

    N.B! I strongly urge anybody 'fooling' with PSUs to buy a test meter. I have several but my £5.00 'Blackspur' is more than good enough for PSU tests. You MUST get that polarity right!!

    Dave.

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  • ICBMICBM Frets: 71963
    I'll have a look in my collection of random power supplies later. I'm not that hopeful though, centre negative is rare - and it's usually impossible to open the unit up and swap it since the casings are glued or welded together. (Or more accurately, impossible without breaking it so you can't safely put it back together.)

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • ecc83ecc83 Frets: 1591
    ICBM said:
    I'll have a look in my collection of random power supplies later. I'm not that hopeful though, centre negative is rare - and it's usually impossible to open the unit up and swap it since the casings are glued or welded together. (Or more accurately, impossible without breaking it so you can't safely put it back together.)


    You can of course chop the cable and flip it then heat shrink the result. MUST check you have got it right with a meter tho'but!

    I have recently binned a few old PSUs (50Hz types, mainly for phones) but I always chop the leads off and save the moulded plug.

    Dave.

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  • Danny1969Danny1969 Frets: 10357
    I normally just cut the cable, then slide a bit of heatshrink over it  ... then separate the 2 conductors ... then cut the positive cable an inch shorter on the charger end and the positive cable an inch shorter on the jack end ... solder the cable back together, the neg conductor will now be the right length to mate with the positive conductor and the fact the wires were cut in a staggered position means the one piece of heatshrink can be slid over both solder joints and there's no chance of them shorting as they are an inch apart under the heatshrink

    If you have no luck yourself I can send you one already done for £15
    www.2020studios.co.uk 
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  • ICBMICBM Frets: 71963
    ecc83 said:

    You can of course chop the cable and flip it then heat shrink the result. MUST check you have got it right with a meter tho'but!
    I don't really like doing that :). It works, but it's a bit of a bodge…

    I found a suitable supply in my box of spares!

    It's the same as one of these… https://www.maplin.co.uk/p/worldwide-60w-acdc-multi-voltage-power-supply-l11bq - although I'll need to find the tips and there's no mains cable with it.

    It is a bit overkill though, at 5A capacity. Maplins also do this one (with very poor photos, but the spec is correct) - https://www.maplin.co.uk/p/maplin-27w-switch-mode-acdc-for-general-use-n47ed

    Given that Maplins aren't a maker and just rebrand things and add a markup, you may be ale to find the same thing for less elsewhere.


    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • prowlaprowla Frets: 4896
    edited September 2017
    Centre -ve is common for 9V ones.

    I've got a switchable one which allows voltage selection (inc. 9V & 12V) and also polarity; I think it's a generic brand. I do have a 12 cente -ve mini 3-channel mixer which I use it with.

    The wierdest one I have is 16V AC, for a Peavey 19" rack synth unit! I've been trying to find a replacement for one of those for a while...
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  • ICBMICBM Frets: 71963
    prowla said:
    Centre -ve is common for 9V ones.
    But almost nothing else outside the musical instrument world. Blame Boss, they started it!

    prowla said:

    The wierdest one I have is 16V AC, for a Peavey 19" rack synth unit! I've been trying to find a replacement for one of those for a while...
    You'll be lucky - AC supplies are now rare, due to modern regulations restricting off-load power draw. Finding one is not helped by the Yanks calling anything which plugs into the mains (which they call 'the AC') an 'AC power supply'. A *lot* of people get caught like that, and buy the equivalent *DC* supply instead - which doesn't work, but rarely causes damage.

    I'll have another look in the box of spare supplies later.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • Danny1969Danny1969 Frets: 10357
    edited September 2017
    Most cheap unregulated DC supplies are AC supplies with 4 diodes for a bridge rectifier and one smoothing cap ..... if you remove the diodes (or cut the legs on the AC side )  and cap you can then take the AC feed from the secondary of the transformer. AC supplies are really common in my work, mainly cos you can get a split supply a lot easier from an AC supply then DC

    @ICBM why did Boss do the centre neg thing again .... I know it's come up before but I can't remember what the reason was behind it ?
    www.2020studios.co.uk 
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  • ICBMICBM Frets: 71963
    Danny1969 said:

    @ICBM why did Boss do the centre neg thing again .... I know it's come up before but I can't remember what the reason was behind it ?
    Possibly because the type of socket they wanted to use has the switch in the sleeve contact rather than the tip, and they wanted to switch the positive battery connection since the negative goes to the input jack.

    They could quite easily have done it with the switch in the negative though, so it may be just that they wanted to force people to buy their - at the time unique, as well as expensive - power supplies.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • ecc83ecc83 Frets: 1591

    Prowla. The Blackstar HT pedals originally used a 16V 800mA line lump AC supply. I think B's still stock a few so if that rating is right for the Yammy rack it might be worth contacting them? No guarantee that the co ax power plug will fit so you might have to kludge it as I mentioned (and IC frowned upon!)

    'Twere me! I would just get a 16V toroid (15V of adequate rating would do*) and put it in a tin. The problem is of course the mains side would need to be done by a qualified tech (and the thing PAT'ed if sold)

    I have read of at least two reasons for neg centre? First Germanium transistors needed a +Ve chassis and so a negative sleeve would short on exposed metalwork. Then, V early pedals and such used a 3.5mm mono jack. Same problem, tip would sparkypoos!

    After the change to Silicon and co ax they COULD have got it right of course but some t**t just didn't!

    *Say you used a traff twice the current rating? The output voltage would not dip so much on the lighter load and be close to 16V. Off load the Bstr supply delivers ~22 volts!  (ANOTHER reason why SMPSUs are much better!)

    Dave

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  • ecc83ecc83 Frets: 1591

    While here about V early HT pedals? They can develop a fault whereby they draw nearly twice 800mA (HT goes to near 450V!) Unhelpfully the pedal still works so you do not know FA until the AC PSU dies.

    If you ever get a dead HT pedal supply DON'T just buy a spare. Get the pedal off to B's or an approved tech'.

    Dave.

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