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Discussion Starter #1 (Edited)
I have a bran new multi-voltage barrel plug type power adapter that is rated for 12 volts and 36 watts.

My device requires 12 volts, 3amps with center pin negative polarity.

When I select the 12 volt setting, along with the negative polarity adapter and plug it into my device, the device control panel is acting as if it is not receiving enough power to fully operate, some of the the lights blink on and off in a pattern but the main LED never lights up.

I believe I may not be getting sufficient current to the device out of this power adapter. How can I check how many amps the power adapter is supplying to my device? I have a multimeter with an 10amp input terminal.

Here is the new adapter I'm trying to use. I have it set to the 12 volt setting and have the negative polarity adapter attached along with the 5.5x2.1mm barrel plug.

 

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The way to test DC current is to place the meter inline with the load.
That power supply is maxed at 3 amps.
Maybe find a higher wattage power supply

Do you have a place to test voltage while the unit is powering up?
 

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Discussion Starter #5 (Edited)
your original comment speaks of a power supply with neg tip
BUT
your picture shows a picture of positive tip ???
is it interchangeable ?
Is it correct ?
Also pictured is the "reverse polarity cable". Inserting that cable changes the positive center pin default to negative center pin as the device expects.

your symptoms are classic overload symptoms
Can you elaborate a bit on that? Meaning the adapter is overloaded by the device's draw or the device is overloaded by the power adapter?

I expect you mean the former (since the device expects 3amps and the max current the adapter is capable of producing is 3amps, possibly at the lowest voltage setting is my suspicion which is why I need to test that), but not sure what you mean otherwise.
 

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You mentioned 12 volts and 36 watts. That implies 3 amps, although if the adapter drew 36 watts from the AC power receptacle, the most you could get at the adapter output would be a little less than 36 watts since the adapter circuitry is not perfectly efficient. (Watts equals volts times amperes for direct current)

The result is that your equipment is really not getting 3 amps at 12 volts.


Measure the voltage at the input to the equipment being powered. If the power supply (the adapter) cannot deliver enough amps then the voltage supplied will drop. Also, try to draw too much and a fuse inside the adapter will (should) blow.
 

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How can I check how many amps the power adapter is supplying to my device? I have a multimeter with an 10amp input terminal.
You need a way of connecting the multi-meter concerned in series between the supply and the load.

This is quite easily done if you have the equipment necessary to do this, which might be as simple as a pair of "alligator clip leads" (https://www.amazon.com/s?k=alligato...ator+clip+leads,aps,1028&ref=nb_sb_ss_sc_1_19) and a suitable nail.

(Think about it !)
 

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Always connect the positive terminal of the power source to the positive connection to the load (or collection of loads).

Connecting an in-line ammeter (which the Amps function of a multimeter is).

Before starting make absolutely positively sure that the load (equipment, device, appliance, etc.) will not draw more amps than the rating of the ammeter.

Connect up the load in the normal manner, without the meter.

Disconnect the positive lead of terminal of the load from the power source.

Connect the positive lead of the meter to the positive terminal of the power source.

Connect the negative lead of the meter to the positive lead or terminal of the load.

For connecting multiple lights or other loads in series, except for the connections to the power source, connect the positive lead or terminal of one load to the negative lead or terminal of the next.

For AC circuits, ignore positive and negative; the two leads or terminals may be connected either way without danger of being connected backwards.
 
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Discussion Starter #11
Thanks for all the help. I finally found an adapter that will power the machine, however, its a loose fit and whenever the machine moves, the power toggles off and on intermittently. The device has a locking nut coupler at the power inlet and my power adapter does not have a locking nut, so the connection is not secure.

Here's my question, I have found a power supply that is matched specs AND has a locking nut connection at the barrel plug. The only problem is that this adapter (like most) is center pin positive (recall my device is center pin negative).

Can I simply splice the cable on this adapter and reverse the wires to get this adapter to work center pin negative?

 

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Discussion Starter #12 (Edited)
This adapter looks alot like this one
https://www.amazon.com/IBERLS-Adapter-Replacement-Keyboard-YPT-410/dp/B07CWN2Z28


It's 18W (spec says max 3A, but that would be @5V)


You need a beefier adapter
Thanks, I actually got the 36watt version of that adapter here:

https://www.amazon.com/gp/product/B07YCJZ2CZ/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

And that's the one I'm referring to in the post above when I indicate that it works to power the elliptical.

The problem is that the connection is a bit loose so power is intermittent on/off because of it.

The original power adapter that came with the machine uses a lockable coupler that securely connects the plug onto the device with a coupler nut. That's why I'm now looking to get a 12 volt 3amp power adapter that has a lockable coupler nut at the barrel end.

The only issue with that is the ones I've found (see pic above post here) are positive center pin units, therefore I'm looking to possibly try one of those by opening it up and swapping the pos/neg wiring to achieve the expected negative center pin polarity the device requires.

FWIW, this is the adapter I'm considering that is 12 volts 5amps, so has more than enough watts to power the device, but is center pin positive. So I'm asking if it should work if I open up the black box and reverse the power wires to make it center pin negative:

https://www.amazon.com/gp/product/B01BLXBLN4/ref=ox_sc_act_title_1?smid=A1C0Y2F1GL2300&psc=1

 

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It is possible that your device has a 2.1 mm socket and the power supply which you now wish to use has a 2.5 mm plug - which will fit, but loosely because that dimension defines the size of the centre pin and not the outside dimensions of the plug/socket.

Check the size of the socket, using the interchangeable connectors you received with the first power supply that you tried.

When you have determined the correct plug, buy one of that size that is designed to be soldered onto the lead concerned, cut off the existing plug and replace it with the appropriate plug - with the supply wires connected correctly.
 

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Discussion Starter #14 (Edited)
FrodoOne, yes, I verified that the best fit is the blue tip connector, which is 2.1mm.

The adapter I'm now looking to purchase, the one with the lockable screw nut connector, does not specify its inner diameter size. That could be an issue even with the locknut on to secure it to the machine's power input socket.

I'm willing to take a chance since the item is returnable and there is really no alternative available as this machine has long been discontinued and the OEM adapter is no longer available.

If it does fit reasonably well, my only question is whether I will do the polarity switch by cutting the wires or by opening the case. I believe opening the case would be the cleaner option when done, but I'd have to use gasoline or denatured alcohol to dissolve the glue seal in order to take it apart. And then super glue or some other epoxy to glue it back once the wires have been resoldered for negative center pin polarity.
 

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The round connector with the center pin was made in more than ten different sizes.

Radio Shack used to sell a selection of adapters with so many volts and so many watts each together with a selection of connector ends that would fit together with either polarity. (If you fitted it together wrong, you fried your device or equipment.)

Yes you could cut the output (low voltage) cable and exchange the two wires inside to reverse the polarity.

Yes you could cut the output cable and do mix and match with "size" of adapter and size of connector end.
 
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If you want to flip the polarity on the power supply I would do that by cutting the 12V wire and swapping sides. Solder and use a bit of heatshrink. Don't 'open the box', it's probably well glued and possibly poured full.
 

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I forget to mention that in the the myriad of different connector plug sizes there are some plug outer diameters for which there may be two or more center hole diameters to go with different center pin thicknesses for the matching equipment jack.

So there is still an element of trial and error when you order parts via eBay, Amazon, etc.
 
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Discussion Starter #19
I forget to mention that in the the myriad of different connector plug sizes there are some plug outer diameters for which there may be two or more center hole diameters to go with different center pin thicknesses for the matching equipment jack.

So there is still an element of trial and error when you order parts via eBay, Amazon, etc.
Exactly, I was about to post an update when I read this. While waiting on this screw on adapter to arrive, I found that the largest diameter plug in this kit, the 5.5mm, is still loose inside the female input of the device.

The device input appears to expect something slightly larger in diameter. Perhaps I can make up the difference with some foil/conductive tape wrapped around the barrel a few times to snug the fit?
 

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Although the surface of conductive tape is conductive foil, when you wrap several layers around the connector plug of something, some brands are not conductive from layer to layer. Some brands are not conductive with a metal surface it is stuck onto.
 
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