Idiot's guide to power adaptors
Old 7th July 2011
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Idiot's guide to power adaptors

Anyone recommend a good readable info page on explaining the various types of power adaptor? Not Wikipedia....

I'm confused by:

- the polarity symbols (if the adaptor shows + -> - then does it go into a device with + -> - or - -> + ?

- AC-AC, AC-DC, DC-DC, DC-AC...and the fact that many adaptors don't even say which type they are.

- the lightweight adaptors used to power PC routers, external hard drives and mobile phones seem to have 100-240v input ratings and heavier adaptors that power heavier equipment seem to have 230v ratings. Why is there such a difference in weight and what other differences are there? Why do these lightweights never work when trying to power music devices even tho' the ratings all match up (output voltage, miliamp etc)?

- the different lengths and thicknesses of the actual connector, some even use audio-type 3.5mm jacks (like those from smaller headphones). My Alesis Microverb II for instance.

- which combinations are potentially harmful to the equipment? When are multi-voltage adaptors not recommended (they don't seem to work on some devices)?

- what does it mean when some power adaptors say "stabilised"? Does it mean they are both AC & DC-compatible? Are "unstabilised" adaptors potentially harmful to the wrong gear?


What are absolute essentials to match up when searching for the correct power adaptor?

I guess output voltage is essential, it has to match up.

Does "Ma", "mAh", "a", "amp", "miliamp" all mean the same thing? I guess the adaptor has to at least offer the miliamp rating of the device, but is also allowed to go over, if it is under the device may not power on.

What about input voltage? Is that country-dependent?

Does polarity mean the same thing as the AC/DC thing? Is AC = + and DC = - ?


I've tried Wikipedia but sometimes it gets so technical the layman just gets confused. I'm sure elsewhere on the net there is a visual and easy-to-read guide to all this...
Old 8th July 2011
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I, too, would benefit from an idiot's guide.
Old 8th July 2011
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+ - ) - is a Positive Tip polarity input.
- - ) + is a Negative Tip polarity input.
These are only needed when you have a DC power supply. IE; Roland boxes.

1000mA is 1amp. So any rating under 1amp is rated as milliamps (millampers). You can use MORE mA than is needed by any given device, as it will just pull what it needs. But never use LESS.

AC-AC means it takes the AC current from your wall, and outputs it to your device. x0xb0x uses this.

AC-DC takes the AC current and switches it to DC. Most units use this. This is where your Polarity comes into play.

If you don't know what kind of power any certain piece of gear uses, best to ask. Don't want to risk blowing your stuff up =o]
Old 8th July 2011
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@Acid Hazard: Short and sweet!

I just looked up the Wikipedia page: IMO TMI

But is had a link to a somewhat simpler description:

Wallwart - DIYWiki


FYI:

DC = Direct Current (Gleichstrom in German)
AC = Alternating Current (Wechselstrom in German)
Old 8th July 2011
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Thanks guys

That DIY Wiki link is much better...bookmarked!


As a serious and somewhat disorganised gear hoarder I find I have more than a couple of devices without correct adaptors.

The icing on the cake which caused this post was when my Solton SAM 8 mixer arrived and the seller claimed he had included a compatible adaptor. Yet all he included was one of those lightweight net-router adaptors with a miliamp rating of 500 whereas the SAM needs 1a (1000 miliamp). He just matched up the output voltage rating and thought nothing more of it.

Unbelievable that there are sellers out there who don't even turn on their device to make sure it works before selling it as "in full working order with compatible power adaptor".


So understanding the weird and wonderful world of power adaptors is essential to better deal with such headaches...
Old 8th July 2011
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Just as above:

If the device requires AC then polarity does not matter. For DC polarity matters!

If you're talking about barrel sockets then there are many different sizes (whichever fits) and polarity in the case of DC - positive or negative centre (aka tip). Other kinds of connectors with more than two pins are custom jobbies. Depending on the quality of the design of the powered device a volt or two higher or lower will work. NEVER try something more than like 5v over.

Also don't mix up AC with DC.

mA or A is amperes, get at least what is asked for, more is better.

Stabilised or "regulated" is a term mostly on DC supplies, basically a number of diodes attempt to keep the DC output as stable to the quality of design. These are used when there is no internal regulator circuitry in the device e.g guitar pedals.
Old 8th July 2011
  #7
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Quote:
Originally Posted by dhollmusik View Post
Anyone recommend a good readable info page on explaining the various types of power adaptor? Not Wikipedia....

I'm confused by:

- the lightweight adaptors used to power PC routers, external hard drives and mobile phones seem to have 100-240v input ratings and heavier adaptors that power heavier equipment seem to have 230v ratings. Why is there such a difference in weight and what other differences are there? Why do these lightweights never work when trying to power music devices even tho' the ratings all match up (output voltage, miliamp etc)?
The lightweight adaptors are what is referred to as 'switched mode' (just a reference to the way the circuit inside works). The heavy adaptors use transformers. It's easy to make 'switched mode' supplies handle different input voltages, harder with transformers.
2 adaptors of different types with the same ratings should work the same, the receiving device doesn't know what's on the other end provided it gets enough juice.
Quote:
- what does it mean when some power adaptors say "stabilised"? Does it mean they are both AC & DC-compatible? Are "unstabilised" adaptors potentially harmful to the wrong gear?
'Stabalised' has nothing to do with AC or DC, stabalised adaptors should put out a stable voltage however much current is drawn (provided it's no more than specced of course). With unstabalised adaptors the voltage can vary with load. Not necessarily harmful, but the device may cut in or distort if the voltage drops too low.
Quote:
What are absolute essentials to match up when searching for the correct power adaptor?
Voltage rating, current, whether AC or DC and if DC the connector polarity.
Quote:
Does "Ma", "mAh", "a", "amp", "miliamp" all mean the same thing? I guess the adaptor has to at least offer the miliamp rating of the device, but is also allowed to go over, if it is under the device may not power on.
mAh is usually used in batteries to indicate how long they are likely to last. TBH I'm not sure how you interpret the figure, thogh of course the higher the better.
Too much current is fine, the device will only draw the current it needs.

Quote:
What about input voltage? Is that country-dependent
Yes, we're 240V here in the UK, the US is 110V, and 220V is used in Europe. Many adaptors can handle the full range of inputs, but if it doesn't say don't assume it can.

Quote:
Does polarity mean the same thing as the AC/DC thing? Is AC = + and DC = - ?
NO , AC and DC are fundamentally different, do NOT get them mixed up. Feed AC volts into a device expecting DC will more than likely damage it.

I see Iain beat me to it...
Old 8th July 2011
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oof, I am third :(

Quote:
Originally Posted by dhollmusik View Post

- the lightweight adaptors used to power PC routers, external hard drives and mobile phones seem to have 100-240v input ratings and heavier adaptors that power heavier equipment seem to have 230v ratings. Why is there such a difference in weight and what other differences are there? Why do these lightweights never work when trying to power music devices even tho' the ratings all match up (output voltage, miliamp etc)?
Chances are the little ones are highly efficient switch mode power supplies which can put out a lot of power very efficiently in a small package (just like a computer power supply). HOWEVER, there are two very important things about these devices that can cause problems for audio devices:

A) The switching action of the supply is very noisy electrically, for purely digital devices, this is of little consequence but for anything analog (or with analog audio outs), that noise will be audible if the device is not set up to deal with a switching supply

B) They are VERY load dependent so the target device needs to be drawing a certain minimum current for it to work correctly.

Standard linear supplies can get pretty large physically for high current ratings

Quote:
- the different lengths and thicknesses of the actual connector, some even use audio-type 3.5mm jacks (like those from smaller headphones). My Alesis Microverb II for instance.
absolutely makes no difference what they use however practicallity is a more of a concern, like using a headphone jack as a power cable almost guarantees someone will plug said headphone style jack into a headphone socket destroying the circuitry there in the process. Price is a big issue as well so the more standard the connectors, the cheaper everything becomes

Quote:
- which combinations are potentially harmful to the equipment? When are multi-voltage adaptors not recommended (they don't seem to work on some devices)?
It all depends on the device. Many devices have on board voltage regulators so all they technically need is a DC supply that is rated ~2V higher than the regulator (a 9V regulator can take 11-32V) but that does not mean you should give it a ton of voltage since it can damage other things that are not rated super high voltage wise. Generally speaking:

-Lower voltage DC into a device expecting a higher DC voltage wont hurt it
-higher voltage DC into a device expecting lower voltage might hurt the device or not at all (probably not at all, older devices did not have over voltage provisions, newer ones almost always do) but you should not run it this way
-DC voltage into a into a device expecting AC voltage wont hurt it, but it wont work
-AC voltage into a device expecting DC voltage will almost DEFINITELY damage the device.

Quote:
- what does it mean when some power adaptors say "stabilised"? Does it mean they are both AC & DC-compatible? Are "unstabilised" adaptors potentially harmful to the wrong gear?
That relates to the regulation of the power supply. A stabilized one is one that has circuitry built into it that ensures that the adapter ALWAYS outputs the same voltage regardless of load (these are always more expensive). An unstablized DC supply will not have that feature so its output, regardless of the what is on the label will be dependent on how much current the device is drawing up to a certain level (i.e. if it is pulling at least x mA, it puts out the voltage shown on the label, if not, the voltage will be HIGHER). This is usually not an issue on newer devices since the regulation is done on the device so a 2v upward swing voltage wise is fine but on older devices (especially ones that are normally battery powered but can also take a wall adapter), you can definitely damage it by using a poorly chosen supply. A perfect example of this is the TR-606 and TB-303, both of which have very small current draws since they are battery powered. The official adapter is a 200mA rated one (with performance known to work correctly) but MANY (and I have fixed a few because of this) people just see 9V DC and plug whatever adapter they have lying around. With an "unstabilized" supply, even if it says 9V DC 800 mA (which is plenty obviously), at the super low current load the device is drawing it may be putting out 15V which can (and does) damage parts in the device. To be safe, you should always use an adapter as closely rated to the original as possible
Quote:
What are absolute essentials to match up when searching for the correct power adaptor?

I guess output voltage is essential, it has to match up.

Does "Ma", "mAh", "a", "amp", "miliamp" all mean the same thing? I guess the adaptor has to at least offer the miliamp rating of the device, but is also allowed to go over, if it is under the device may not power on.
Correct, for DC devices its Polarity, Voltage, current (which always has to be at least the same as what is spec'd)
AC devices just need the voltage and current to be correct, there is no polarity

Quote:
What about input voltage? Is that country-dependent?
oh yes. For wall warts, its not to big of a deal since you cant plug a US supply into a Euro wall socket, they dont fit. There is a huge difference between Europe and the US/Asia (Eu is twice the voltage)

Quote:
Does polarity mean the same thing as the AC/DC thing? Is AC = + and DC = - ?
no.

AC = Alternating current. Essentially a sine wave that alternates between two wires, there is no + or -

DC= Direct current, current flows from the positive to the negative terminal. ( Hence + or -)

Mains votages are always high voltage AC (it is easier to transmit AC over long distances), the transformer will convert that to low voltage AC which is then passed on to the device (the AC to AC adapter) or converted to low voltage AC which is then further converted to DC (AC to DC adapter)

Last edited by Altitude909; 8th July 2011 at 01:48 AM.. Reason: Ha! I belive myself and steveman are on the same page :)
Old 8th July 2011
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Thanks for your post, Iain.

What about adaptors which don't state whether they are DC or AC and also don't have a polarity symbol?


EDIT: wow, just seen your contributions, steveman & altitude909 )

nice one
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Old 8th July 2011
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Quote:
Originally Posted by dhollmusik View Post
What about adaptors which don't state whether they are DC or AC and also don't have a polarity symbol?
This adapter is AC (or Wechselstrom). Look for the little sine wave symbol:

9V ~ 1.3 A



AC Output = No Polarity!
Old 8th July 2011
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Quote:
Originally Posted by seen-da-sizer View Post
This adapter is AC (or Wechselstrom). Look for the little sine wave symbol:

9V ~ 1.3 A
Blimey...it's no wonder some people blow up their machines...I mean, how many of us knew that symbol meant AC?

Well, I do now so thanks for that.


Also, I have another adaptor and it's confusing as it's called AC/DC...but it shows a polarity symbol of - -> + ... my Solton mixer shows a polarity symbol also of - -> +


The Solton requires: DC / 12v / 1A / - -> +

this adaptor is: AC/DC / 12v / 800mA / - -> +

so not compatible for two reason: the polarity doesn't match (assuming they have to be opposite like batteries do), second reason is the amperes rating of the adaptor isn't sufficient.

Is that correct?
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Old 8th July 2011
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Quote:
Originally Posted by dhollmusik View Post
Also, I have another adaptor and it's confusing as it's called AC/DC...but it shows a polarity symbol of - -> + ... my Solton mixer shows a polarity symbol also of - -> +


The Solton requires: DC / 12v / 1A / - -> +

this adaptor is: AC/DC / 12v / 800mA / - -> +

so not compatible for two reason: the polarity doesn't match (assuming they have to be opposite like batteries do)
Incorrect: The polarities on the AC Adapter and the symbol on your device have to match! It is like "jumping" you car battery: plus connects to plus, minus connects to minus.


Quote:
Originally Posted by dhollmusik View Post
second reason is the amperes rating of the adaptor isn't sufficient.

Is that correct?
Correct. Get an adapter with at least 1A (or 1000mA). You can go over the value with something like 1.2A.
Old 8th July 2011
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Quote:
Originally Posted by seen-da-sizer View Post
Incorrect: The polarities on the AC Adapter and the symbol on your device have to match! It is like "jumping" you car battery: plus connects to plus, minus connects to minus.

aaaaaaaah...confused again, because:

Quote:
Originally Posted by Altitude909 View Post
AC voltage into a device expecting DC voltage will almost DEFINITELY damage the device.

AC = Alternating current. Essentially a sine wave that alternates between two wires, there is no + or -
Quote:
Originally Posted by seen-da-sizer View Post
AC Output = No Polarity!
Did you mean to write "AC/DC" adaptor?


So, let me see if I've got all this right...


AC/DC

- The Easy-Line adaptor is no AC adaptor, it's an AC/DC.
- The HPro adaptor is no AC/DC, it's an AC adaptor.
- The term "AC adaptor" refers to an "AC/AC adaptor". An "AC/AC" adaptor is NOT safe to put in a "DC" device.
- The term "DC adaptor" refers to an "AC/DC adaptor". An "AC/DC" adaptor is safe to put in a "DC" device.
- An AC/DC adaptor will have polarity symbols. These symbols have to match the device (not be the opposite).
- AC adaptors are known by their lack of a polarity symbol, and/or by the presence of the "~" symbol.
- AC/DC adaptors (the same as DC adaptor) may be plugged into AC devices without danger to the device.
- AC/AC adaptors (the same as AC adaptors) may be plugged into AC devices without danger to the device.


currents and voltages:

- the amp rating of the adaptor has to be at least as large as the rating the device requires.
- the output voltage rating of the adaptor has to be the same rating as the device requires. Give or take 1 or 2v may be ok in some cases.
- the input voltage rating of the adaptor has to match your country's electricity rating (Germany = 230v). Lightweight (switching) adaptors may have a 100-240v rating, this is ok.
- Switching adaptors may work for some music devices, but they may cause audio-interference with analogue devices, or devices with analogue in/outputs.
- the Hz and watt ratings are generally not relevant for our purposes and we don't need to pay attention to them-



Is all that correct?


Thanks guys, you've all been diamond on this thread...really helped this idiot understand the whole thing better.
Old 8th July 2011
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By law, every power adapter has to indicate the voltage, AC, or DC, and the rated current draw in milliamps or amps. If you are unsure of polarity, get a cheap multimeter and connect the dots. The meter should indicate a positive or negative reading depending on where the probe is.
Old 8th July 2011
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Quote:
Originally Posted by dhollmusik View Post
Did you mean to write "AC/DC" adaptor
They are all AC adaptors! It is a generic term and they are called this way because the input is AC! It adapts AC to something.

Input: AC -> The magic black box -> Output: AC or DC (with a specified Voltage and Current, measured in Ampere.)

When I shortened to "AC Output" you do have this:

Input: AC -> Transformer -> Output AC. (or AC/AC)

That should make it clear?


Quote:
Originally Posted by dhollmusik View Post
Thanks guys, you've all been diamond on this thread...really helped this idiot understand the whole thing better.
I don't think you are alone in this. Due to the lack of clear standards one could easily get confused. And yes, I did plug-in the wrong AC adapter once and fried my Dimension D.
Old 8th July 2011
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Quote:
Originally Posted by dhollmusik View Post
Blimey...it's no wonder some people blow up their machines...I mean, how many of us knew that symbol meant AC?

Well, I do now so thanks for that.


Also, I have another adaptor and it's confusing as it's called AC/DC...but it shows a polarity symbol of - -> + ... my Solton mixer shows a polarity symbol also of - -> +


The Solton requires: DC / 12v / 1A / - -> +

this adaptor is: AC/DC / 12v / 800mA / - -> +

so not compatible for two reason: the polarity doesn't match (assuming they have to be opposite like batteries do), second reason is the amperes rating of the adaptor isn't sufficient.

Is that correct?
That adapter label is very clear. It's a transformer that is taking "wall AC power 230 volts" on it's primary side and transforming it on the secondary side to 12 volts DC. and it's rated at 800 milliamps which is 200 milliamps shy of an amp. The little diagram is showing you the polarity of the connector. The center pin (the hollow inside of the connector) is +. The sleeve or (outer shell of the connector) is -.
Old 8th July 2011
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All of these adapters are transforming AC wall power from your home into a "low voltage" power source. That low voltage power source that they end up converting for you can be DC low voltage, or AC low voltage. All you have to do is to carefully read the label. You can seriously screw up a device if you get that wrong.
Old 8th July 2011
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Quote:
Originally Posted by seen-da-sizer View Post
This adapter is AC (or Wechselstrom). Look for the little sine wave symbol:

9V ~ 1.3 A



AC Output = No Polarity!
Harman Pro owns JBL, DBX, CROWN, etc. the sine wave might not be something most consumers would recognize as indicating the type of voltage. Most pro audio people would. That adapter is no doubt specific to a piece of pro audio gear. If it needed to be replaced, most people would refer to the specification documetns for the device and find a suitable replacement. And by the way, with an AC output..polarity isn't relevant. It's AC, so yeah.
Old 8th July 2011
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Big fat thanks to Teknobeam, seen-da-sizer, Altitude909, steveman, lain2097 and Acid Hazard for helping me finally understand a really important aspect of music hardware.

Old 8th July 2011
  #20
What no ac/dc jokes?


Old 12th July 2011
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Like Detective Columbo, I just have one more question...

what about when the polarity symbol is both ways?


The device I want to try it is:

DC - 12v - 500mA . polarity: - -> +

I understand this adaptor is DC (called AC/DC?) because it doesn't have the sine wave symbol on the output (Ausgang) section. But as it has both polarity symbols does it mean it is compatible with both types of polarity?

Thanks again
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Old 12th July 2011
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And here's an AC/DC adaptor with no polarity symbol at all...

man, I thought I grasped this and along comes more confusing adaptors
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Old 12th July 2011
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Quote:
Originally Posted by dhollmusik View Post
This looks like that you switch the polarity in either "Rotating the DC plug" or there must a different plug all together. Is there a "polarity symbol" on the DC plug? I am thinking something like this:



As for the 2nd AC adapter, do you have a manual?
Old 12th July 2011
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Quote:
Originally Posted by seen-da-sizer View Post
This looks like that you switch the polarity in either "Rotating the DC plug" or there must a different plug all together. Is there a "polarity symbol" on the DC plug?

As for the 2nd AC adapter, do you have a manual?
Thanks for replying, seen-da-sizer...good tip about checking the plug...I found the polarity symbols...tho' they seem to go both ways. Also with both plugs they are not removable, they are permanent.

The first two images with the rounded neck is the "amplus", which is the second adaptor with no polarity symbols on its label. The 3rd & 4th pic with the more flat neck is from the "H&H" adaptor with both polarity symbols.


I don't have a manual, no...just going through all my gear (I really have lots and lots of gear) and trying to match up power adaptors...
Attached Thumbnails
Idiot's guide to power adaptors-amplus-back.jpg   Idiot's guide to power adaptors-amplus-front.jpg   Idiot's guide to power adaptors-h-h-back.jpg   Idiot's guide to power adaptors-h-h-front.jpg  
Old 12th July 2011
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Quote:
Originally Posted by dhollmusik View Post
Thanks for replying, seen-da-sizer...good tip about checking the plug...I found the polarity symbols...tho' they seem to go both ways. Also with both plugs they are not removable, they are permanent.
They are either stuck (most likely, the entire plug will separate in two parts), or you must "twist" (very unlikely) them to change the polarity. And this is true for both of your AC adapters! RTFM would help here!

-On the "H&H" adaptor polarity symbol has to face the arrow. It is currently set to +o)- (plus on tip)
-On the other AC adaptor: it is currently setup for +o)- (plus on tip; the word used here is CENTER)

Try to pull the connector (metal) part while holding the plastic end of the plug with your other hand. I never saw a twisting connector, but I would not exclude it from the possibilities. Though that would be a very unsafe way of doing this.
Old 12th July 2011
  #26
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Quote:
Originally Posted by seen-da-sizer View Post
I am thinking something like this:


Quote:
Originally Posted by seen-da-sizer View Post
They are either stuck (most likely, the entire plug will separate in two parts)...

-On the "H&H" adaptor polarity symbol has to face the arrow. It is currently set to +o)- (plus on tip)
-On the other AC adaptor: it is currently setup for +o)- (plus on tip; the word used here is CENTER)

You were right They were just a bit stuck...a little force has revealed exactly what you showed in this diagram.

Phew! haha...thanks a lot, mate...this little hiccup in understanding has been overwinded (as we say in German...probably sounds a little weird in English).


Prost!
Old 12th July 2011
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Quote:
Originally Posted by dhollmusik View Post
(as we say in German...probably sounds a little weird in English.
It does! But at least you did not use "overtwisted"!
Old 12th July 2011
  #28
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Quote:
Originally Posted by seen-da-sizer View Post
It does! But at least you did not use "overtwisted"!

overtwisted just sounds peverse...

...like something George Michael might do in the public toilets with Stephen Milligan.



Old 12th July 2011
  #29
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Quote:
Originally Posted by dhollmusik View Post
Like Detective Columbo, I just have one more question...
Ha ! Columbo. That IS classic Columbo.They worked that little item into every episode. That show would still be a hit today if they re ran it. Loved it.
Old 16th August 2011
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Quote:
Originally Posted by dhollmusik View Post
I'm confused by:

- the polarity symbols (if the adaptor shows + -> - then does it go into a device with + -> - or - -> + ?
Quote:
Originally Posted by seen-da-sizer View Post
Incorrect: The polarities on the AC Adapter and the symbol on your device have to match! It is like "jumping" you car battery: plus connects to plus, minus connects to minus.

I've just re-read this thread and this one thing still confuses me. If the polarity symbols have to match then how come my Yamaha PA-3C Adaptor with + -> - is able to power my MFB-522 with requires - -> + ?

Is it dangerously foolish to use this adaptor if its polarity is the wrong way to the device? I've used it so far with no issues.
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