[WXC/VFX] VFX Linksys gear

Forums › Vodafone New Zealand › [WXC/VFX] VFX Linksys gear - PSU was faulty

SATTV

564 posts

Ultimate Geek
+1 received by user: 148

Topic # 83028 9-May-2011 12:01

Hi All,
Just a comment really.
After going through 2 * WAG54GP2 devices, 3 * WAG310G devices I now have a SPA2102
I had to buy a SPA2102 about 18 months ago when there was no stock of the WAG310G.
Anyway, the SPA2102 has been playing up for a wee while, crackling line and poor performance.
I changed the power supply like a few people had mentioned and the call quality is back to perfect.
I could not believe the SMPS could do that, I would have thought there would have been another filtering cap on the device end to take away any PSU ripple and fluctuations.
Anyway if you are have trouble with the voice quality, try changing the power supply. It has worked for me.
What I would like to see is a dual / triple outlet PSU so I only have to have one pluged in that can feed the Modem, The ATA and the Switch.

Cheers
John

I know enough to be dangerous

Niel

3267 posts

Uber Geek
+1 received by user: 77

Trusted

Reply # 467709 10-May-2011 18:49

The output capacitor filters a lot of ripple, and is filled with an electrolyte. Over time it dries out, series resistance increases, the capacitor heats up, and it pops open. Then the voltage control loop is upset, can't react fast enough to load changes.

The other failure mode is the rectified-mains bulk storage capacitor dries up. Or dried solder joints around power devices (MOSFET and rectifier diode).

On PC power supplies the symptoms are reduced by using many capacitors in parallel, but they also degrade faster than you expect.

You can never have enough Volvos!

SATTV

564 posts

Ultimate Geek
+1 received by user: 148

Reply # 468021 11-May-2011 18:56

True but I would not expect that after 18 months, after 5 years or so I would expect problems with caps drying up.
When i used to repair VCR's ( remember them ) I would always use 105 deg or 125 deg caps in the PSU, they cost a few cents more but lasted alot longer.
When I used to import cap's they were the same price for 105 deg as the standard 85 deg so we never stocked or sold the 85 deg caps.
I guess when you are building 100k units a week and can save 10cents a PSU it adds up to big savings.
Hard to buy quality any more.
John

I know enough to be dangerous