Troubleshooting router

Power supply failure due to bulging caps. I'm guessing you have the white or gray Apple airport that looks like a conical mushroom. I have 3 of those in a box with similar symptoms. The only difference is that the light was flashing for only a few days before it started acting weird.

Leo Laporte, a real fanboi, says to avoid those Apple routers. They are nothing but trouble, even when the do work.

Routers should be religion free, er makes that OS independent. So the notion that anyone needs an Apple router is at best silly.

Wall-Wart are made by the bottom of the food chain in China. It's really sad because they are critical to performance (Doh!). Netgear has especially crappy wal wart suppliers.

I predicted doom and gloom when wall warts went to offline switchers rather than poorly regulated linear supplies, but I was totally wrong. I haven't had a cheap ass Chinese switcher wall wart fail. Some of these are sure noisy as far as RF emissions go.

I have to agree. Made by Lucent with considerable "inovation" inspired by Apple insisting on a very low price point. My experience with them at customers has been dismal. The later model Airports are better, but far from perfect.

Immitation is the sincerest form of flattery:

Yes but easily fixed (with a hammer and soldering iron):

Agreed. I have to unplug all my switchers when on HF. I've had plenty of switchers fail. However, it's usually not the electronics. It's the crappy cords and fragile connectors.

I have a few switching warts that scream RF. I found some switchers at a local surplus shop labeled Proton SPR-218F-05. I bought one on a lark and it was much quieter, so I wiped the shop out the next time I was there. [$4] It has quite a few specs on the back, but as we've learned, stuff out of Asia has all sorts of marking without the certificates to back them up. Level 3 LR99922, ite 1Z49 level 3, ul e143742 (nothing turns up relevant in google)

This is the one that is beige-ish and shaped more like a rounded off pizza box. It doesn't look like the one on the web page.

I'm wondering if this could be cable failure. While I don't see any frank fraying, there is a gap between the end of the plug and the start of the blue coating on the wire. Also I get the same problem when I plug in my other Airport (the smaller one that looks like a cigarette pack on steroids).

MOre than likely, and a cable substitute is the first step in trouble shooting.

Especially since I just got done swapping out my big router for the little one I travel with occassionally with the same outcome.

The small one is the Airport Express. The cable you're looking at is the ethernet cable. The gap between the connector and the outer jacket is not important since it carries no signals. As long as the wires at the ends of the ethernet cable are intact and making a connection, it should work.

However, as I vaguely recall (and can't check until I get to my palatial office today), the flashing yellow light on the Apple Mushroom wireless router means that the ethernet cable is wired wrong or backwards. You might check your ethernet cables and where they are connected.

Ethernet cables going south are not unheard of. I wasted quite a bit of time once due to a bad ethernet cable. I buy the shielded ones mostly because they tend to be tougher.

The newer routers have autosensing and can swap on the fly. I assume there is a standard in the industry where only routers can autosense.

Nah, Apple's stuff has had that capability for years. My ol' Sawtooth, for instance, and certainly our newer machines. I can't imagine any NIC without it.

Long shielded cables give me problems. I had shielded running between two buildings which happened to be on two different grounding systems. There was only a few millivolts between the grounds, but they had the power of PG&E between them. There was no pyrotechnics or smoke, but plenty of odd problems that magically went away when I lifted *ONE* ground. I had a similar situation with coax cable between buildings many years ago. This time, the cable got warm, sparks flew, and the shield eventually fused open (in the most inconvenient place possible).

Interesting. I just use them over short distances. Ethernet uses transformers, so I assume there is no issue with the unshielded cables. It would help to know how they use the shield in the overall cable configuration.

I know for building to building use in corporate installations, they go fiber just to get around the ground differential. Nowadays for bandwidth too, but I recall back in the day fiber wasn't all that fast (due to the interface hardware), they used it for the ground issue. Math Associates comes to mind. I heard lots of complaints from the IT guys. Looks like Irwin Math is still kicking:

I see fiber optic cards in the surplus shops these day, so perhaps the technology is getting more mainstream.

The shields are connected to the "frame" of the RJ45 jack, which is connected to the frame ground. The data wires are rated to 1500 volt isolation from ground. The problem is that the subsequent internal circuitry is not so well isolated, especially when the box is passing a bunch of noise and ripple current directly from the power line going through the box, through the shield, and through the box at the other end. The length of the cable should have little effect as the common mode rejection of the data lines will prevent any coupling from the shield from affecting the data. It's unlikely to find grounds ad different potentials with short cables. However, with really long cables, even grounds on the other side of a build may become a problem.

Incidentally, the way I found one culprit was that someone turned off the lights in the wiring closet while I was working. When I unpluged a patch cable, I noticed a small spark. Not a great way to do troubleshooting but sometimes luck works.