Archive for June, 2011

Netgear wireless router repair

My wifi internet connection has been slowly deteriorating. I originally thought it was my trusty old IBM T42 going out, but when I got my Alienware M15x it was still bad with that machine. I’ve had a few problems with this router: it sometimes refuses to allow wireless connections to access the gateway. If you log in to the router’s interface over wifi via it’s IP and clear the log, it will then allow wifi access to the gateway. I set up the router to automatically email the log to an email address when the log is full. That worked for most of the time, but occasionally you still have to log in and do it manually.

Recently though the connection speed over wifi plummeted. I was going to buy a new wireless AP, but I’m pretty cashed at the moment so I took the router apart to see if I could buy some time.

Wifi router with heatsinks

You could pretty clearly see that the microprocessor has overheated. The conformal coating is brown on the bottom side of the PCB. I used an infrared thermometer to measure the temperature of the chip, it was running at about 74°C. The ethernet switch controller IC had a similar temperature, but it’s a larger leaded package whereas the CPU looks like a BGA package. I had some memory heatsinks that I cut to fit the two chips, and with that and some thermal paste I had heatsinks for the two heaters in my router case. They are low profile enough that the case will still go on.

My router works like it should again: reports an average of 18Mbps download speed. The heatsinks keep both ICs at about 49°C now. Guess I won’t need that new AP for a while.

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Tuesday, June 28th, 2011 Electronics 4 Comments

Canon DSLR shutter release from any switch contact

I’ve long wanted a TC-80N3 remote release for my EOS1D for the long exposure and intervalometer capability. Unfortunately a real Canon one is at least $150, and just out of principle I’m not paying that. A couple months ago I decided to just try one of the identical but rebranded ones off of eBay for $20. Ships from Hong Kong, Shenzen, etc. so it takes a while to get here, but it works, so I’m happy. I can never leave well enough alone though, so I took it apart and added a jack so I can hook anything with a switch contact to my camera and let it take a picture.

Remote release with external jack

It’s pretty straightforward, there’s three metal contacts. The lowest one is ground, the next one is prefocus, and the last one is the shutter release. The signals are active low. I wired the three to a headphone jack on the bottom of the remote. To test it out I bought a ten dollar motion sensing security light and took out the motion sensor, then wired the output of the sensor to a 120VAC relay. The relay contacts trigger the shutter whenever the motion sensor sees anything.

You can use anything with a switch contact to trigger the camera, just remember that it’s not protected. If you mess up, you can easily fry your camera. Look for “dry” contacts if you are unsure. Canon DSLRs might allow for transistor pull-downs, but I haven’t tried that. It’s easier to just create an isolated contact through a relay for the safety of your camera.

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Tuesday, June 28th, 2011 Cameras 2 Comments

Alienware AlienFX repair

So the other day I was browsing craigslist looking for a way to get rid of one of my Xbox 360s. I found a posting for an Alienware m15x laptop, which said they would be willing to trade for an Xbox. It had an issue where it would shut down if you moved the lid. Since it was otherwise working, had the 1920×1200 LCD, T9500 CPU, 4GB RAM, Blu-ray, etc. I picked it up.
I tore it down and figured out the problem: the wire bundle for the lid’s AlienFX lights was chafed bad where it goes through the hinge. It was shorting out which is why it would shut down. I carefully seperated out the melted wires and repaired the bundle with a fine-gauge hard drive cable.

AlienFX wiring bundle repair

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Friday, June 10th, 2011 Electronics 8 Comments