AT&T 2701 HG Power Supply Failure (again)

[SMS]

My 2nd power supply for the AT&T 2701HG failed last night. First I
thought it was a DSL outage, but the sonic.net person knew that the
problem was probably a power supply (the 2701 powers-on but can't sync
and the wireless router section doesn't work) since their database
showed a history of power supply failures.

It's an interesting and annoying failure mode for a switching power
supply that it's apparently supplying enough power to light the power
LED, but not to do anything else.

An emergency soldering/heat shrink job with the cut-off connector from
the AT&T supply attached to a spare $5.95 Sun 1U server supply solved
the problem, hopefully for a long time.

<http://www.mpja.com/prodinfo.asp?number=17602+PS>

I also may order a stash of the $5.95 Cisco 5V 4A supplies
<http://www.mpja.com/prodinfo.asp?number=18464+PS>, since those Sun
server supplies are rather ridiculously sized for a modem/router.

No more supplies from Weird Stuff as I got two bad supplies in a row
from them.

[Jeff Liebermann]

Post by SMS
My 2nd power supply for the AT&T 2701HG failed last night. First I
thought it was a DSL outage, but the sonic.net person knew that the
problem was probably a power supply (the 2701 powers-on but can't sync
and the wireless router section doesn't work) since their database
showed a history of power supply failures.

Yep. I happen to be at the local recyclers (a favorite hangout) when
someone rolled up with several large boxes full of 2wire wall warts.
My guess is about 2000 wall warts. I grabbed a few on the assumption
that they all can't be bad. Out of about 10, half were genuinely
dead. Sorry, no photos.

Post by SMS
It's an interesting and annoying failure mode for a switching power
supply that it's apparently supplying enough power to light the power
LED, but not to do anything else.

It's also difficult to tell if it's blown. A no-load voltage test
will show about 5.3VDC. You have to put a load on it to tell that
it's kaput.

Post by SMS
An emergency soldering/heat shrink job with the cut-off connector from
the AT&T supply attached to a spare $5.95 Sun 1U server supply solved
the problem, hopefully for a long time.
<http://www.mpja.com/prodinfo.asp?number=17602+PS>

Well, I suspect that has enough current capability to drive the 2701.

Post by SMS
I also may order a stash of the $5.95 Cisco 5V 4A supplies
<http://www.mpja.com/prodinfo.asp?number=18464+PS>, since those Sun
server supplies are rather ridiculously sized for a modem/router.

Stock power supply from AT&T
<http://www.att.com/equipment/accessory-details/?q_categoryid=cat2020062&q_sku=sku3950283>

Post by SMS
No more supplies from Weird Stuff as I got two bad supplies in a row
from them.

I've had a rash of failures of 5V 2A power supplies over the years.
It's not just 2wire, but literally every other device and manufacturer
that uses them. Mostly Netgear switches, but also other odd devices.
I have no idea what is causing the problem, but after dissecting a
Netgear 5V 2A supply, I suspect crappy workmanship. The only ones
that seem to survive forever are the 5V power supplies for various
Cisco/Linksys/Sipura VoIP hardware (Model AD 5V/2F).

Also, what I've done is try to eliminate as many wall warts as
possible and run them all off a common power source. I have a 5V and
12V bus driven by an open frame switcher similar to your Sun PS. Lots
of pigtails with connectors completes the system. The 12V line is
backed up by a battery, but the 5V line is currently unprotected
(because my 6V battery died from overcharging).

[Steve Fenwick]

Post by Jeff Liebermann
Also, what I've done is try to eliminate as many wall warts as
possible and run them all off a common power source. I have a 5V and
12V bus driven by an open frame switcher similar to your Sun PS. Lots
of pigtails with connectors completes the system. The 12V line is
backed up by a battery, but the 5V line is currently unprotected
(because my 6V battery died from overcharging).

I've thought about that, but SAF is low (breaks UL for the individual
devices), open-frame is unattractive, and it gives me One Big Point of
Failure. Do you have the individual outputs fused/breakered?

Steve

[Jeff Liebermann]

On Wed, 17 Aug 2011 13:59:42 -0700, Steve Fenwick

Post by Steve Fenwick

Post by Jeff Liebermann
Also, what I've done is try to eliminate as many wall warts as
possible and run them all off a common power source. I have a 5V and
12V bus driven by an open frame switcher similar to your Sun PS. Lots
of pigtails with connectors completes the system. The 12V line is
backed up by a battery, but the 5V line is currently unprotected
(because my 6V battery died from overcharging).

I've thought about that, but SAF is low (breaks UL for the individual
devices), open-frame is unattractive, and it gives me One Big Point of
Failure.

True. However, my plan is to stay up for extended periods during
power outages. A single well designed charger tends to generate less
RFI than a mess of small wall warts. This is what I'm trying to
avoid:
<http://802.11junk.com/jeffl/pics/drivel/slides/wall-wart-01.html>
The ham radio pile, some LED lights, and other devices run on the same
system. I keep a box of wall warts, spare gel cell, and a 117V UPS
nearby, but that's only for extended emergencies or failures.

Open frame is not a good term, as most open frame switchers include
fully enclosed (perforated) covers. If you get one without a cover,
it's easy enough to buy some perforated aluminum or steel stock at the
hardware store and make your own.

Incidentally, PCB mount power supplies and DC to DC converters are
sized by the "brick".
Full brick 4.6 x 2.4 x 0.5
Half brick 2.3 x 2.4 x 0.35
Quarter brick 2.3 x 1.45 x 0.35
Dropping one on your toe will help explain the origin of the term.

Post by Steve Fenwick
Do you have the individual outputs fused/breakered?

Sorta. The primary side is fused in case of PS failure or battery
short. There's one output fuse for 12V and another for 5V but it's
not individually fused by output. This wasn't exactly planned but
sorta grew slowly as new boxes arrived. The wiring is also rather
messy so no photo for now.

Hint: Avoid devices that run on 9VAC, like most of my music
synthesizers and boxes. Grrrr...

Major oops: I've been ranting for about a year about the failing
2wire 2701HG DSL modem/router. I found 5 "dead" 2701HG modems in a
box in the office. I haven't retested the routers, but I just checked
the power supplies with a 1.5A (3.3 ohm 10 watt load). They're all
sick. I replace the bulging caps on one ps, and that fixed it.

[Jeff Liebermann]

Post by Jeff Liebermann
I've had a rash of failures of 5V 2A power supplies over the years.
It's not just 2wire, but literally every other device and manufacturer
that uses them. Mostly Netgear switches, but also other odd devices.
I have no idea what is causing the problem, but after dissecting a
Netgear 5V 2A supply, I suspect crappy workmanship.

This is typical. Netgear 12v 1A PS:
<Loading Image...>
I replaced the capacitor, but that didn't fix it.

2Wire Modem Power Supply repair:

[Bhairitu]

Post by SMS
My 2nd power supply for the AT&T 2701HG failed last night. First I
thought it was a DSL outage, but the sonic.net person knew that the
problem was probably a power supply (the 2701 powers-on but can't sync
and the wireless router section doesn't work) since their database
showed a history of power supply failures.
It's an interesting and annoying failure mode for a switching power
supply that it's apparently supplying enough power to light the power
LED, but not to do anything else.
An emergency soldering/heat shrink job with the cut-off connector from
the AT&T supply attached to a spare $5.95 Sun 1U server supply solved
the problem, hopefully for a long time.
<http://www.mpja.com/prodinfo.asp?number=17602+PS>
I also may order a stash of the $5.95 Cisco 5V 4A supplies
<http://www.mpja.com/prodinfo.asp?number=18464+PS>, since those Sun
server supplies are rather ridiculously sized for a modem/router.
No more supplies from Weird Stuff as I got two bad supplies in a row
from them.

I got my 2wire power supply two day delivered from Texas for no extra
charge other than the $10 for the adapter. But you might see if the
AT&T store has them since those have come into existence since I got my
replacement. I was able to use my Sony PSP power supply in the meantime
since it was rated the same and had the same connector.

[Bhairitu]

Post by Bhairitu

Post by SMS
My 2nd power supply for the AT&T 2701HG failed last night. First I
thought it was a DSL outage, but the sonic.net person knew that the
problem was probably a power supply (the 2701 powers-on but can't sync
and the wireless router section doesn't work) since their database
showed a history of power supply failures.
It's an interesting and annoying failure mode for a switching power
supply that it's apparently supplying enough power to light the power
LED, but not to do anything else.
An emergency soldering/heat shrink job with the cut-off connector from
the AT&T supply attached to a spare $5.95 Sun 1U server supply solved
the problem, hopefully for a long time.
<http://www.mpja.com/prodinfo.asp?number=17602+PS>
I also may order a stash of the $5.95 Cisco 5V 4A supplies
<http://www.mpja.com/prodinfo.asp?number=18464+PS>, since those Sun
server supplies are rather ridiculously sized for a modem/router.
No more supplies from Weird Stuff as I got two bad supplies in a row
from them.

I got my 2wire power supply two day delivered from Texas for no extra
charge other than the $10 for the adapter. But you might see if the AT&T
store has them since those have come into existence since I got my
replacement. I was able to use my Sony PSP power supply in the meantime
since it was rated the same and had the same connector.

That $10 PS is also for the 2701HG. The link for ordering is here
(third item down):
http://www.att.com/equipment/accessories/gateways-routers-modems.jsp

But AT&T has set up stores for U-Verse just like Comcast has and though
I haven't visited one you might call them and see if they have them in
stock.

[Kevin McMurtrie]

Post by SMS
My 2nd power supply for the AT&T 2701HG failed last night. First I
thought it was a DSL outage, but the sonic.net person knew that the
problem was probably a power supply (the 2701 powers-on but can't sync
and the wireless router section doesn't work) since their database
showed a history of power supply failures.
It's an interesting and annoying failure mode for a switching power
supply that it's apparently supplying enough power to light the power
LED, but not to do anything else.
An emergency soldering/heat shrink job with the cut-off connector from
the AT&T supply attached to a spare $5.95 Sun 1U server supply solved
the problem, hopefully for a long time.
<http://www.mpja.com/prodinfo.asp?number=17602+PS>
I also may order a stash of the $5.95 Cisco 5V 4A supplies
<http://www.mpja.com/prodinfo.asp?number=18464+PS>, since those Sun
server supplies are rather ridiculously sized for a modem/router.
No more supplies from Weird Stuff as I got two bad supplies in a row
from them.

Avoid the switching power supply wall warts sold by Jameco. They have
massive switching noise and leakage on the output. Mine showed 65V AC
open circuit and 3mA AC short circuit compared to ground. They'll not
only kill your DSL signal, but cause buzzing on your phone line.

[SMS]

Post by Kevin McMurtrie

Post by SMS
My 2nd power supply for the AT&T 2701HG failed last night. First I
thought it was a DSL outage, but the sonic.net person knew that the
problem was probably a power supply (the 2701 powers-on but can't sync
and the wireless router section doesn't work) since their database
showed a history of power supply failures.
It's an interesting and annoying failure mode for a switching power
supply that it's apparently supplying enough power to light the power
LED, but not to do anything else.
An emergency soldering/heat shrink job with the cut-off connector from
the AT&T supply attached to a spare $5.95 Sun 1U server supply solved
the problem, hopefully for a long time.
<http://www.mpja.com/prodinfo.asp?number=17602+PS>
I also may order a stash of the $5.95 Cisco 5V 4A supplies
<http://www.mpja.com/prodinfo.asp?number=18464+PS>, since those Sun
server supplies are rather ridiculously sized for a modem/router.
No more supplies from Weird Stuff as I got two bad supplies in a row
from them.

Avoid the switching power supply wall warts sold by Jameco. They have
massive switching noise and leakage on the output. Mine showed 65V AC
open circuit and 3mA AC short circuit compared to ground. They'll not
only kill your DSL signal, but cause buzzing on your phone line.

There was noise on the phone line from the AT&T supplied wall wart as well.

The current set-up I have is really overkill, but it works and it's
cool-running, but using a lot more power, so I need to switch to a lower
wattage supply.

But if you ever need some cheap power supplies for other projects, those
1U Sun server supplies are very nice for $5.95, and better quality than
most of the el-cheapo PC power supplies.

[SMS]

Post by Kevin McMurtrie
Avoid the switching power supply wall warts sold by Jameco. They have
massive switching noise and leakage on the output. Mine showed 65V AC
open circuit and 3mA AC short circuit compared to ground. They'll not
only kill your DSL signal, but cause buzzing on your phone line.

Thanks for that warning, I've been buying stuff from Jameco/James since
about 1975! Their prices for wall power adapters are very high, more
than 2x what I'm paying for the Delta/Cisco adapter.

[David Kaye]

It's an interesting and annoying failure mode for a switching power supply
that it's apparently supplying enough power to light the power LED, but
not to do anything else.

Maybe an ATX power supply might be worth using? Those units are remarkable.
You can short them and they'll just cut out. Plus, they provide plenty of
oomph at 5 and 12vdc. A friend uses them for science experiments, etc.

Sure, there's the fan, but, well, at least you know the thing is keeping its
cool...