Why cant i connect a different power adapter to power stuff?

[borgqueenx]

i have this mini HD 1080p media player. but sometimes it blacks out and returns...touching the power adapter will make it black out more.
So the power adapter is damaged.
the original power adapter is 5.2V and can deliver 2000mA.
So, i have got a other power adapter, cut the ends of the cables so i can put it on the other one. I switched the ends of the adapters, and tried to power the media player again with the new adapter. Didnt do anything.
But why?
it is also an adapter wich gives 5V and can deliver 2000mA.
Cables are corretly connected(negative and positive)
i currently do not have a working multimeter...it broke.

after it didnt work i switched the ends again and used the old adapter and voilla it worked again. but i again, dont want this piece of junk adapter since it makes blackouts.

its hard to believe that 0.2V makes a difference..

EDIT: just tried another 5V adapter, wich can give 1000mA. no luck.
Very weird...

maybe trying to switch the cables will work? or is that dangerous? ^^ (putting positive on negative)

 

[borgqueenx]

Someone?

 

[Bionic-Badger]

Get a multimeter first. As a stop-gap, take a look at the barrel-jack connector diagram (if you're using that) to see what part of the jack is positive, and which part is negative. e.g.

Both the power adapter and the device should have one. Make sure they match.

If that doesn't work your device is probably busted.

 

[borgqueenx]

I fixed it. I woke up this morning thinking, what if i reverse the cables in the connector? Because i thought chinese where always making crap they could have switched cables in the first place. And they did. I have put the white cable on black, and vice versa. Works again
Ive looked at that diagram, and they are desame.

 

[Bionic-Badger]

Ouch, switched cables? That's terrible build quality.

 

[borgqueenx]

Ouch, switched cables? That's terrible build quality.

yeah indeed xD. really a chinese quality adapter. i mean the adapter i tried was 5V and 2000mA. Then why wouldnt it work! it was only 0.2V difference between the broken adapter!
So thats why i switched the cables and it worked, tadaaa!

really really really crap build skills at that factory lol.

 

[vk2fro]

Your probably luck the PJ has a protection diode inside to protect against reverse polarity. Otherwise most probably you'd let out the magic smoke, and that stuff is really hard to get back in.

As an aside, an easy way to test polarity without a multimeter is to use an LED and suitable resistor. Attach the anode to a red wire, and the resistor to the cathode of the led, and a black wire to the other end of the resistor. If you follow the barrel plug diagram on the adapter, you'll soon find out if its miswired - the led wont illuminate if connected backwards.