Power Adapters Matter

August 18, 2006

A friend of mine had been having a terrible time with his internet connection and his Airport Express Airtunes/iTunes setup. It all started when he got hit by lightning and had to replace his router.

The setup was like this (--> means wired connection):

Config 1
Cable Modem--> Linksys router (4-port switch)
Linksys router --> iMac
Linksys router --> Airport Express
Linksys router --> Airport Extreme

After reconnecting, and finally getting the internet working again, he could no longer "see" either of his Airports from his iMac. We beat our heads against the wall for quite a while over this, but I eventually had him go buy an ethernet switch to use in place of the switch in the router. So, the new setup looked like this:

Config 2
Cable Modem--> Linksys router (4-port switch)
Linksys router --> Ethernet switch
Ethernet switch --> iMac
Ethernet switch --> Airport Express
Ethernet switch --> Airport Extreme

This solved the problem. I'm still trying to figure out if the router switch was just plain bad, or somehow was filtering the Airport connections.

But then he got hit by lightning again, and blew out the second router. This time he bought a Linksys Wireless router to replace it. He plugged it all back in just the way it was in Config 2, but could never get it to work. He could plug the iMac into the cable modem, and that worked, but no other setup seemed to work. So, he sent me out to his house to have a look.

The first thing I noticed was that he had laid out all three routers (the two dead ones which were identical, and the wireless one) for me to look over. Upon examining these, I realized that there were only two power adapters-- one connected to the second dead router, and one connected to the wireless router-- with one still in the box. The power adapters were, to the casual eye, identical.

I checked the voltages on the power adapters, and sure enough, two were 9 volt, and one was 12 volt. The wireless router had a 9-volt power adapter plugged in to it. I couldn't find the spec on the router itself, but guessed that it must be 12 volt, based on process of elimination. My friend had left the old power adapter in place, and just plugged the new router in to it.

So, I plugged in the 12 volt power adapter to the new router and that solved the problem. Moral of the story: replace it ALL when you have to replace something.

I still don't know why the the Linksys router somehow blocked or filtered the connection to his Airports. If you know of a reason, I'd love to hear from you at "bill at metatation dot com."