SparkFun Forums

[newbiebot]

Hi,
I think I sadly killed a router, at least I want to know how I did it so don't repeat the mistake! Being newbie is costly

I added a usb stick with 8GB to my router wr703n so that to boot it from the card. I successfully got it to boot from there. Next I wanted to add a sound card and camera by a hub to the usb port of router. It is logical to not to expect all the power from the usb port of router, so in this way I decided to use a battery of 12v@7a and have 7805 chip for items (all ok with ~5v). I started from the memory card and you will find here the image schema how I hacked the usb cable to have the usb stick get the power from 7805. Right after connecting the battery, the router gone for ever never worked again!


my questions please:
1. what I did wrong please?
2. can I expect any smd fuse on the router (wr703n) so hopefully to repair it, or to forget it is the fate?

[waltr]

A 7805 requires a few caps on both its input and output.
Find a 7805 data sheet from National Semi and read the requirements and study the typical circuits.

FYI:
a 7805 does not have Base, collector, emitter pins. It has Vin, ground and Vout pins.

[falingtrea]

First of all the 7805 is not a transistor so your nomenclature is wrong. It has an in pin an out pin and a common pin and the tab is also common. Second, USB is 5V not 6V so running the USB memory stick at 6V may be the reason for why you blew up the router.

If you are worried about sourcing power on the USB, then isolate the USB devices with a self powered USB Hub. Then the hub is the only unit being directly powered by the USB host connection.

[Valen]

Ehm, maybe a stupid question, (but sometimes turns out to be a valid solution). Did you check the router function when you disconnected every thing that isn't supposed to be connected? Maybe you only blew up the USB port.

EDIT and this site may be of help solving the issue:

http://wiki.openwrt.org/toh/tp-link/tl- ... onsumption

[newbiebot]

Thank you everybody for information.

Yes, I used the wrong B.C.E. there, but in practice I connected wires correctly there. I didn't show the caps there but they are there soldered to my 7805, I was just drawing that schema in a hurry, I should have been do it in Eagle and the right way, sorry again.

I just wanted to check: to my eyes the wiring seems absolutely correct, I don't think I did a mistake in connecting them. Shocked of how fired the router.

It is dead and that's not only the usb port, unfortunately. The led of the router will not turn on no more and no sense of it when connected to Ethernet port.

Now another question: if I use a powered hub, how could I be sure that it gives enough power to everything connected to it. I mean, the hub creator didn't know what I am going to use there! That's why I thought I have to power things separately.

On the hub, I have a web cam, a pl2303, an sd card reader + mp3 player.

[Valen]

The USB standard defines that a port should normally provide upto 100 mA, and allowed to provide 500mA when requested by a devicedescriptor setting of the plugged in device. So the manufacturer of the hub should have made it to supply atleast the number of ports times 500 mA.

[EDIT] the powered hub should have a label somewhere how it is to be supplied with power. And should come with some sort of power adapter that has a output rating. That dc-dc converter should be able to supply that, in addition to the load of the router itself.

How did you power this hub anyway. There is no indication in your drawing of how it is connected.

[newbiebot]

The USB standard defines that a port should normally provide upto 100 mA, and allowed to provide 500mA when requested by a devicedescriptor setting of the plugged in device. So the manufacturer of the hub should have made it to supply atleast the number of ports times 500 mA.

True, but I use some Chinese hub and can't really count on this.

[Valen]

In that case, your only option is to test what it can deliver with a dummy load. Something like this might be usefull:

https://www.tindie.com/products/arachni ... ummy-load/

Or this, if you only need inspiration and make it yourself:
http://www.eevblog.com/2010/08/01/eevbl ... y-testing/

[newbiebot]

In that case, your only option is to test what it can deliver with a dummy load. Something like this might be usefull:

https://www.tindie.com/products/arachni ... ummy-load/

Or this, if you only need inspiration and make it yourself:
http://www.eevblog.com/2010/08/01/eevbl ... y-testing/

Thank you very much for information. I think I'm now getting closer to 'why I burned the router'. To make a new question into a new post, I continued the topic here:
https://forum.sparkfun.com/viewtopic.php?f=42&t=37080

If possible please have a look.

[Valen]

I don't see why you need to create another thread. The new one has less information in it that might have been relevant. Infact the reason you made this thread in the first place was to get an answer on how you killed the router.

[newbiebot]

I suspect the alligators used to connect the power wire of the router to the 12v @ 7amp battery.

I sometimes have seen sparks when connecting them. Could anyone tell me why there is sparks please? I suspect that in that time big flow of charges created amp that the device could not bear and burned. I should have put a fuse there. Do you think this is a correct conclusion please?