[colug-432] Linux Router/MODEM: Power Supply Status: Dead

[jep200404 at columbus.rr.com]

On Fri, 10 Feb 2012 16:30:13 -0600, Thomas Cranston <thomas.w.cranston at gmail.com> wrote:

> [Wall wart power supply is] Not dead. Is supplying correct voltage. 

Presumably under no load. 

> Makes the other DI-704 light up. 

OK. That's good enough to declare the recently unhelpful DI-704, bad. 

> Speaking of wall warts, I looked at USRobotics Faxmodem page. It's
> power supply appears to be of the older big hunk of stuff vintage.
> Terminology? 

Older wall warts use line frequency (60 Hz) transformers. 
The overall style of old wall warts is called "linear". 

Newer wall warts often are switch mode power supplies (SMPS)
which use a small transformer at a much much higher frequency 
(30 kHz and up). 

> Maybe there is a dependability issue.

Well duh! Something quite working. 

Conservativity designed and built stuff will last a long long time. 
That goes for everything, including but not limited to both 
linear and switch mode power supplies. 
When corners are cut, dependability decreases. 

SMPSs are much more complicated than linear ones. When corners 
are cut on SMPSs and linear power supplies, I think the cheap 
SMPSs are more prone to failure than their cheap linear cousins. 

Each have their strengths. Each have their weaknesses. 

I have seen both die. 

Have you checked the caps inside the router to see if they are 
bulged? Search the web for bulged capacitors.