[asterisk-users] TDM400p susceptible to EMI?

[Steve Edwards]

> On Wed, Jul 13, 2011 at 2:51 PM, Steve Edwards 
> <asterisk.org at sedwards.com> wrote:

>> I have a TDM400p with 3 fxs and 1 fxo daughter cards.
>>
>> It's in a mini-itx case with a 'right-angle' PCI riser card so the 
>> TDM400p is 'sandwiched' between the Atom D525 CPU and the 2.5" hard 
>> drive.
>>
>> I'm getting a bunch of clicks and pops on all ports.
>>
>> Has anybody had a similar experience? Did you find a solution?

On Wed, 13 Jul 2011, Tim Nelson wrote:

> Many Mini-ITX cases have horrific power supplies to keep overall cost 
> down. 'Cheap' doesn't begin to describe them. They *will* introduce 
> audio issues, especially where you're using FXS modules.

This box is using a picoPSU-80 80w DC-DC 'power supply' fed from an inline 
'laptop brick.'

> Also, it could be your system's ability to handle interrupts as that 
> will cause clicks/pops as well.

Out of 300 samples from dahdi_test, there were 3 'outliers' -- 70.317%, 
87.397%, 95.899% which is not comforting, but they don't correlate with 
the stream of noise.

> Third, try putting the card directly into the motherboard. PCI risers 
> can be finicky, especially the 'ribbon style' units. The solid PCB units 
> I've found are typically fine.

This case will not accommodate that unfortunately. This is a rigid PCB 
unit.

-- 
Thanks in advance,
-------------------------------------------------------------------------
Steve Edwards       sedwards at sedwards.com      Voice: +1-760-468-3867 PST
Newline                                              Fax: +1-760-731-3000