Overheating Cable Modem


I have a Terayon TJ 715X Cable Modem that I received when I got my Cox account. It has worked fine for about 14 months but lately I have been getting a strange problem. The "Cable" light will stop being solid and then start blinking slowly for hours. During that time I have no internet. If I leave the modem unplugged from power for about two hours it will work but usually returns. I took it apart today and touched the Coaxial RF-In "box" and it was VERY warm. I blew on it for about a minute and when it was cooler reassembled the modem and connected everything. It started up and connected to the internet very quickly. I figured the casing was too restrictive so I cut the plastic above the RF thing out of the case. It was working for about 20 minutes and then stopped again. The back of where I cut felt hot. I took the entire thing apart. Right now as I write here is the situation: The modem board is encased in a thin metal that goes around it. The way it was put together was there is a plastic case, and that is in two pieces. Each piece has a thin metal half. When the plastic is put together the inner metal case touches. The modem board is inside that. The modem is open and on my desk next to me. I left it in the metal case but have removed the plastic case. All is fine so far but I was wondering if there is any danger to me? Until I can get a small fan to run through the plastic case I need to let it sit out. Can it, while operating, leak any waves that can be harmful. I know that microwaves are bad and read that when making a "cantenna" for a wifi setup not to look into it while it is operating cause that could hurt you.

Any help, ideas or suggestions on anything I wrote would be appreciated.



Reply to
Johnny Public
Loading thread data ...

Why can't you just contact the cable company and get them to replace the modem?

Reply to

They're making these modems might cheap nowadays.

First make sure you have the right AC adapter! One of too high a voltage will cause the modem to overheat. Then blow any dust out of the ventilation holes. Don't set the modem on a thick rug as that will block the vent holes. Don't run the modem on its side, it needs the holes at the top and bottom for convection.

Then check to see if any heatsinks have fallen off the chips. These are stuck-on nowadays with a little double-sided tape. Sometimes these fall off for various reasons. They also slide off if you operate the modem or router at an unusual angle!

Reply to

Call the cable company for a replacement, rather than having something that will soon fail, and you will have no service.

Jerry G. ======

Reply to
Jerry G.

You could check for any cracked solder joints but I would probably just replace the modem unless you're looking for a challenge. They're pretty cheap.

Reply to
James Sweet

On 20 Mar 2006 15:16:32 -0800, "Ancient_Hacker" put finger to keyboard and composed:

AFAIK, these modems tend to use onboard switchmode regulators, so overheating in the power supply may not be a real concern. Instead I'd be adding heatsinks to the bigger chips and drilling more vent holes.

- Franc Zabkar

Please remove one 'i' from my address when replying by email.
Reply to
Franc Zabkar


I initially thought that it was their cable line that was causing the problem. I called and set up and appointment for them to come out and when I spoke with the customer service rep they said that if it isn't the line it would be $49.95 for the tech. If it was the modem I would be charged the $49.95 for the tech and then $50 for a new modem. I bought the modem when I started service with them (Cox Cable) and am not leasing it. Therefore they say it is my property and equipment.


Reply to
Johnny Public

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.