Power Fried

Discussion in 'Cisco/Linksys Wireless Routers' started by kuntushi, Oct 28, 2006.

  1. kuntushi

    kuntushi LI Guru Member


    I recently got a version 1.0 (serial CDF1...) WRT54G which someone thought they had killed, so gave to me. After playing with the power supply (the actually wall plug DC converter), I found that it it was only giving out 3V, and had probably died (which seemed common with these things). So I got a new power supply, gave it 12V-ish with a max of 1A... which should be fine.

    However, it's not fine haha. The power and diag light stay on solid (and quite bright) and the Broadcom BCM4702 gets insanely hot. It's probably safe to say the Broadcom chips is toast, but does anyone know why this might have happened? The regulators are meant to take upto 40V... it seems like they just decided not.

    I measured the voltage at the plug at around 5V... didn't measure the voltage at the LED's... but I'm guessing it'd be around 5V as they are brighter than normal.

    Has anyone seen this problem before, or have any idea what to do? I'm happy to replace the regulators... the BC chip is another matter haha.

    Oh... I remeber when I first plugged it in, all the link lights were flashing real quick. Stopped doing that after I plugged it in a few times though.
  2. vincentfox

    vincentfox Network Guru Member

    The v1.0 unit used a 5V wart with 2.0A. Try using one closer to that specification.
  3. kuntushi

    kuntushi LI Guru Member

    This thing goes down to 6V 1A. But don't they have regulators that can take up to 40V anyways?

    Also, would it already be fried you think? Or is there a chance everything is still running fine?
  4. anectine17

    anectine17 Network Guru Member

    If you put 12 volts to the v.1.....even briefly, it's toast. They're 5 volt creatures and die instantly if you give them much more than 8. Live and learn.
  5. kuntushi

    kuntushi LI Guru Member

    haha, oh well. So much for them going higher than that haha. It was already broken anyway, so it's not so bad.

    What exactly blows in those things though? The buck chip seems fried... but would any of the irreplaceable hardware be gone... like the BroadCom Chip?

    Also, just for future reference, at what version did they start being able to take upto 40V (rated, not recommeded)?
  6. anectine17

    anectine17 Network Guru Member

    I haven't figured out yet what goes when it's internal. I've gotten pretty good at repairing the v.1 power supplies when they go. They just had bad capacitors....one in particular. I just replace all the caps and they're better than new. I'd sure like to find what it is on the board that goes cuz I've got a box full of v.1's I could fix.

    As for the change in voltage, the v.1 is the only of the WRT54 series that used a 5 volt PS. At v. 1.1 they moved to the 12 volt, 1 amp unit. I know these are more forgiving than the 5 volt, v. 1's, but I've heard nothing about being able to put 40 volts to them. I wouldn't attempt it!!
  7. kuntushi

    kuntushi LI Guru Member

    haha, yeah, I don't think I would either. Shame about the router I've fried, now I'll never know what was wrong with it in the first place. It just stopped working one day apparently. Probably was just the power supply going.... shame I screwed a perfectly good board :(

    Actually, I plug the old supplyy in, and still get 4.1V coming in. It's funny, cause the whole board is at 4.1V, which makes me think the buck went (more likely one of the 4 caps around it). I have a feeling that the 12V would of friend more than that after it went direct into most things though. I guess I could replace the caps and find out, but I don't have any handy.

    Have you ever tried that anectine? Worth a go at least once, maybe that's all that blows. The setup in these routers was better than I expected... switch mode power and all. Maybe their components are tollerant to some nasty shocks (other than the standard caps that is). If you do try it, and it works... give us a yell, and I'll try it on mine. For now though, I'll just pick myself up one on eBay.
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