Checking wall wart for devices

[Scott Shepherd]

I'm sure some of you can help me here. I'm an electricity moron. Sorry to say, but it's true. I've been asked by a friend to help troubleshoot a piece of exercise equipment. I think it's one of those elliptical things. It's got a screen that lets you adjust various things, I suppose. Time, workout plan, and stuff like that. The machine runs for about 4 minutes exactly and then cuts off. It's using a wall wart (that might not be the name, but that's what I call them), power supply. There was a slight pinch in the cable, so I stripped it, cut the wires and soldered them back together and I thought to myself "Can't you just put a meter on it and see if maybe it's bad? So I put the meter (forgive me for saying things that aren't electronically accurate) on DC, then I put one probe into the barrel of the connector and then the black one on the outside diameter of the connector. I don't get readings anywhere near what's listed on the power supply. So am I measuring it wrong, is it clearly bad since the readings don't measure correctly, or am I doing something wrong?


It says on the power supply :
Input : 120V 60Hz 7W
Output : 6VDC 500Ma

When I check the volts the way mentioned above, it showed 9.3v. When I check the Amps, it shows 2.5A.

To me, seems like the output voltage and amps are wrong. But I don't know enough to know. Maybe I have something set wrong, maybe it's right and it only works when it's powering something?

Any insight into how to tell if this thing is bad?

He said it's an older machine and not supported by the factory, so they were no help to him (which is why he asked me).

[Dan Hintz]

No idea what's in the wall wart (could be a switching supply, but probably not), but if it's anything more than a transformer, rectifier, and cap, you may need a load on it to measure the correct voltage. For all of the trouble, though, just pick up a new wall wart if you can't get that one sorted... shouldn't cost you more than about $10.

[Scott Shepherd]

No idea what's in the wall wart (could be a switching supply, but probably not), but if it's anything more than a transformer, rectifier, and cap, you may need a load on it to measure the correct voltage. For all of the trouble, though, just pick up a new wall wart if you can't get that one sorted... shouldn't cost you more than about $10.

Thanks Dan, I think he said Radio Shack wanted like $30-35 for one and he wasn't anxious to spend that much to find out it wasn't the problem. Got a good source for them for the $10 range? If so, I'll order it myself and spare myself $10 worth of time :)

[Dan Hintz]

Don't remember if they have a minimum order surcharge...
http://www.digikey.com/product-search/en?FV=fff40009%2Cfff8004a%2C4f80074%2C11800048%2C1 180005c%2C118000a5%2C118000cb%2C11800144%2C1180015 b&k=wall+wart&mnonly=0&newproducts=0&ColumnSort=1000011&page=1&stock=0&pbfree=0&rohs=0&quantity=&ptm=0&fid=0&pageSize=25

Prices start at about $7...

[Myk Rian]

9.3 volts is ok. With a load on it, that will drop to 6.
You can't measure amps unless you have the meter in-line with the output. There is no way you'll read 2.5 amps on a 500 milliamp supply.

[Duane Meadows]

NEVER hookup an ammeter across a power supply! Good way at an absolute least to destroy the ammeter, or the power supply! Sounds to me like the supply(wall wart, if you will) is ok! Generally they are not well(or at all) regulated. The cap that Dan mentioned makes it peak reading... therefore I'd expect about 8.5 Volts minimum without a load!

More likely the console on the machine is bad, Could also be missing a tach pulse to the console... oft times a reed switch and a magnet that moves past it.

[Duane Meadows]

9.3 volts is ok. With a load on it, that will drop to 6.
You can't measure amps unless you have the meter in-line with the output. There is no way you'll read 2.5 amps on a 500 milliamp supply.

Well, you may for a short time... the voltage at that point however is near zero. The ammeter is essentially a dead short on the supply. Not proper use of an ammeter(I know I said that once but can't over emphasize that!)

[Jerome Stanek]

We had a treadmill that would do this it was the motor over heating from dust and hair.

[Jim Matthews]

We had a treadmill that would do this it was the motor over heating from dust and hair.

+1 on a little house cleaning.

I (very briefly) held a job servicing home exercise equipment after years working in hospitals.
I though it would be nice to get out and about.

The condition of most equipment that failed was best described as slovenly.
The amount of lint these things capture, with their air circulating fans placed at floor level is astounding.

The fact that some of these motor drive apmplifiers don't spontaneously burst into flames, with a blanket of Bowser's fur covering the heat sinks is
a credit to the robust design skills of the schmuck that was tasked to make a durable part for less than a dolla.

I'm with JS - try a vacuum cleaner, and call the manufacturer for a replacement Power supply.

[Duane Meadows]

There is a LOT of difference between an elliptical and a treadmill... totally different types of things. A 6 Volt 500 mA DC supplies don't run large motors, period! If it is shutting off in an exact time from start up, most likely it is missing a tach(speed) signal to the console! If it does not receive the tach signal, it assumes you are not exercising! Does the digital speed info actually display till it quits? I used to change a lot of both the consoles and the reed switches on this type of machine(mostly Icon/Proform, but others also). Make and model and I may be able to give you a good guess!


Nothing in most ellipticals that dust will cause to over heat, just isn't!

[Myk Rian]

+1 on Duanes' comment. I manage the weight room at our senior center. Treadmills are disaster areas underneath them. Ellipticals, not so bad.

Tip: If you don't know what you're doing around electricity, get someone else to do it. Really.

[Scott Shepherd]

Tip: If you don't know what you're doing around electricity, get someone else to do it. Really.

Now where's the fun in that? :) Sooooo.....looks like my comment about being an electricity moron was accurate! I promise to never ever check a power supply with a meter again :)

Duane, I think it's a Norditrack (or however they spell it). I'll have to get him to check the display. I don't know what it shows. I'm not sure if it's a digital display or just led's that light up in bars for progress. I've only seen it powered on once and I don't remember. I'll call him and find out the specifics. I do know he said it would run 4 minutes plus or minus a few seconds and then shut off every time.

[Jerome Stanek]

It still sounds like the motor overload is tripping.

[Duane Meadows]

Jerome, WHAT MOTOR? Think upright bicycle! Actually it probably has a tension control motor, no overload, only runs if you are changing the tension.

Scott, if it's a Nordictrack , my best advice is "quit while you are ahead". I positively despised working on those things!