Noria power cord adapter question

[Welchs101]

HI,

My daughters noria 7inch tablet is not turning on or charging that we can tell. So i pulled the adapter apart (which was easy because they have a screw holding it together) to look at it.

Observation1: I noticed that while charging the adapter "smelled" like hot wire smell and it was "warm" to the touch.

Observation2: Look at pic1.......labeling says output in DC is 5V/2000mA

Observation3: Look at pic2.......i actually plugged this in and measured between nodes 1 and 2 and i measured 5.52V dc.

So i guess this means the adapter is ok........right? or is there something else i should check on the adapter to make sure its running ok.

[stj]

Re: Noria power cord adapter question

check the cable that carries the 5v

[selldoor]

Re: Noria power cord adapter question

Does the charger have a led - does it go out when plugged in?
What voltage does it output when plugged into the tablet?

Wondering if a short in the tablet

[Welchs101]

Re: Noria power cord adapter question

thats kinda hard to do.......the opening that plugs into the tablet is "very" small any ideas what to put in there keep in mind i dont want to short anything out........

[selldoor]

Re: Noria power cord adapter question

No - what voltage shows where you have marked 1 and 2 when connected to the tablet

[Welchs101]

Re: Noria power cord adapter question

not sure......but good question i will measure and get back to you

[Th3_uN1Qu3]

Re: Noria power cord adapter question

Take the tablet apart and resolder the charging jack. It is always the problem on cheap tablets.

[mariushm]

Re: Noria power cord adapter question

That 5v @ 2000mA on the label is kind of wishful thinking... i doubt a 7" tablet uses that much current to charge, or that the charger is actually capable of providing that much current.

Please, just go and buy a "brand name" phone charger or a somewhat higher end 5v @ 1000mA or higher power adapter.
Then, cut the cable somewhere and connect the cable of this old charger in its place so that you'll have the proper connector. Making sure the polarity of the wires remains the same (you can use a multimeter but the wires should be colored differently so it would be easy without one)

The circuitry inside the current adapter is horrible and doesn't seem capable of actually producing 2000 mA, more like 300-500 mA. In addition, the wires in the cable with the connector are so thin that they wouldn't handle 2000 mA in the first place.

[CapLeaker]

Re: Noria power cord adapter question

there is nothing much wrong with the charger itself. The only thing that could be wrong is if it couldn't provide any current. In that chase just replace the output cap and you are back in business. I think there is something going on inside that tablet.

I've got tablets and smart phones (Asus, Samsung, Apple) in all sizes. All can be charged with 5V 2000mah. Cording to my current meter they will actually come very close to that too. If I'd be charging my Ipad on 500mah, it would take a full day to charge!

[mariushm]

Re: Noria power cord adapter question

Nothing much wrong?

No pi filter ... see there spot for an inductor and capacitor missing, they just soldered the wires directly on ground and where the inductor was supposed to be. Red wire should go to Vo+ but since inductor is missing they had to solder the wire there.
Components missing in the feedback path, by the optocoupler, maybe it's not even working.
The transformer is undersized, i sincerely doubt it can do 1000mA.
The diode by the transformer should be rated for 2-3A if the charger is supposed to be capable of 2000mA - that diode looks more like 1A max. If it's rated for 2A, have a second look at datasheet, it would be rated 2A at 70c temperature or something like that, if the case is hot and you smell something, you can bet the insides are probably much hotter than that. Luckily diodes are more resilient in general, they don't fail often.
The wires are simply undersized for that current, at 2000mA you would have A LOT of voltage drop on the cable. Luckily, at idle this adapter outputs 5.5-5.6v so at 2A the output voltage is probably more like 4.5v if the adapter can even do that. The smell of hot wire is probably the insulation on the cables getting hot because the wire is thin and therefore heats up.

This charger looks and probably is SHITTY. Your Asus, Samsung, Apple chargers may very well do 1-2A without any problems, but they're in a totally different league compared to this charger.

[goontron]

Re: Noria power cord adapter question

there is nothing much wrong with the charger itself. The only thing that could be wrong is if it couldn't provide any current. In that chase just replace the output cap and you are back in business. I think there is something going on inside that tablet.

I've got tablets and smart phones (Asus, Samsung, Apple) in all sizes. All can be charged with 5V 2000mah. Cording to my current meter they will actually come very close to that too. If I'd be charging my Ipad on 500mah, it would take a full day to charge!

that things a joke. wrong creepage distance for 230v, poorly designed feedback regulation (and a high drift opto), no fuse or sacrificial resistor, no pi filter, etc.

[CapLeaker]

Re: Noria power cord adapter question

Given the design of that charger is shitty at best (yeah, I know that too), but that's not what I meant. What I meant was what is wrong with it and why it may not work quite right and gets hot. Never even heard about Noria, but that is beside the point.

[kaboom]

Re: Noria power cord adapter question

that things a joke. wrong creepage distance for 230v, poorly designed feedback regulation (and a high drift opto), no fuse or sacrificial resistor, no pi filter, etc.

+100!

The ripple from that thing is going to kill the tablet. Maybe not now, but it will over time. That tablet will be the next "Adam computer*."

Welchs, cut the plug off that junker and solder it onto the end of this:
http://www.allelectronics.com/make-a...-supply/1.html

Don't even waste the time with these junk supplies.

*The Adam computer was a system I worked on back in 2007. It belonged to a friend of a friend. It had an asus P4P800-E, P4HT 3000/800FSB and 1 or 2MB L2 cache. Not positive- I didn't have the sSpec. 768MB of DDR and some high powered (for its time) video card. It had a cheep case that was "reinforced" by the motherboard.

"Deer season" had come and the system probably had over a volt of ripple on +12. The ripple from the PS was heterodyning with the switching freq of the other buck converters in the system, like the ones on that video card, as well as the one for the CPU! You could hear the "beat note" in the fan and HDD motors!

I did a reinstall for him, thinking I'd be able to squeeze it in while the new PS was on the way, but after changing some settings in MSCONFIG, that damn PS began squealing and I made a bee-line to pull the plug- but right as I got to the plug, it quieted. So I collected myself and was able to "gracefully" shut down windoze.

Afterwards, I tore out the Deer and ripped it apart. I tested his HDD and CDRW on one of my supplies- they appeared ok.

I got the new PS and put it in- no more whine or beat notes. For the sake of it, I reinstalled it again, not wanting to take any chances of corrupt data from lousy power. The system appeared to be fine after that, other than the cheesy case. I/we brought it over to him, left it and all was well- even tried out the "audio system" with that nice old SB Live.

Guess what? It came back a week or two later and all CMOS settings had defaulted and windows "lost it," as if it no longer held the device/driver config. Resetting the BIOS didn't do it- it was hit 'n miss in windows, and the BIOS was squirrelly. No, I didn't know about the KZGs/KZJs back then, and the Deer certainly didn't help. I didn't even offer to recap it since I could tell he wan't happy with that system- I would've felt bad asking him to put even more money into it.

It was such a problem that I offered to give/trade him a different system over this- again, he already had money in this, not just to me, but to whoever he first got it from. This sums it up: the "version" of windows it had when he got it was "windows vista." IOW, every instance of "WinXP" was "typed over" with the words "windows vista."

A bootlegged "OS," complete with "sony/ericsson phone phreaking" tools on the desktop.

So he ended up with a Gateway 7600 I "recovered" before being trashed, with a P3-700. I think I put 1GB RAM in that and it certainly ran well enough for him. The best part was how much less power it used- that damn "Presshot" made his room too hot in the summer... surprise-surprise

Welchs, while there may be a cap in the output of that thing, I certainly wouldn't trust it. It's likely of dubious quality, and the lack of pi-filtering affects the poor device connected to it. It was bad enough in my above example, it'll be an outright disaster in that little tablet.

CapLeaker, of course it get hot and smells like burnt varnish/wire- the transformer is undersized and overheating. That thing could fault primary to secondary. And w/o an EGC, the entire tablet (and everything/everyone) connected to it will be floating at line voltage. Needless to say, the heat also killed the caps. I had this same "dusty burnt varnish" smell from the Deer PS above.

Think about the "shocking i-devices." Fake power supplies were used, which faulted, either from being sloppily made (with wires touching), or transformer overheating/breakdown. The users were unaware of this until the following conditions were satisfied:

Unit connected to fake supply, and fake supply plugged into AC power
Headphones, or other cables plugged in that were in contact with user
User then contacts a grounded object, completing the fault path and shocking themselves

TL,DR

Welchs, this sort of junk had no place even back in 2007. Do yourself a big favor and throw it away. Don't pour your money down a rathole.

[Welchs101]

Re: Noria power cord adapter question

wow, came back tonight and did not expect this much info........

so thanks.


should i even make the measurement you guys mentioned or should i just order the new charger

thanks again

[kaboom]

Re: Noria power cord adapter question

wow, came back tonight and did not expect this much info........

so thanks.


should i even make the measurement you guys mentioned or should i just order the new charger

thanks again

You're welcome.

As long as you can't think of any problems with splicing the old plug onto the cord from the new supply, you should be ok. I'd cut the old cord near the plug, leaving a 6-8 inch tail. To get at the wires inside, try a wire stripper for #10-12 AWG and gently sort of score the insulation. You'll be able to remove it w/o damaging the two wires inside. The cable from the supply is a miniature "zip-cord," which should be easy to work with.

That's a pretty small plug, so splicing it this way might be easier than cutting the actual connector out of the overmold.

Make certain to check the polarity before plugging it into the tablet! You don't want to let the smoke out.

Don't forget to slide the heatshrink on before you solder it!

[selldoor]

Re: Noria power cord adapter question

It will take only minutes to do the test and as mentioned earlier open the tablet and look at the connector - they often come unsoldered from the board.

[Welchs101]

Re: Noria power cord adapter question

i opened it up........but its going to take me a while to get to the "pins" of the connector. i have to take a few things off......

[selldoor]

Re: Noria power cord adapter question

Why dont you do the test I suggested first- set it all up switch it on and test inside
the adapter where you marked it?

[kaboom]

Re: Noria power cord adapter question

Better yet, cut the cord off the old supply (you'll have to anyway to splice it) and tie red and black to the red/black of a computer power supply.

Verifies that tablet still works and does so w/o using the "ripple supply."

After what I went through with that damn Deer, "testing" a device with a junk power supply would be the last thing I'd recommend.

[japlytic]

Re: Noria power cord adapter question

As far as you may know, a number of cheap tablets come with a skimpy (and likely to be unsafe) AC adaptor.
Some time ago, I've read that some low cost mobile phone car kits can melt when used due to the wire gauge being too thin.