Router and Power Supply information - Bad Capacitors

Post new topic   Reply to topic    DD-WRT Forum Forum Index -> Broadcom SoC based Hardware
Goto page Previous  1, 2, 3, 4  Next
Author Message
thx-1138
DD-WRT Novice


Joined: 18 Aug 2009
Posts: 24

PostPosted: Tue Aug 25, 2009 3:21    Post subject: Reply with quote
Quote:
The original capacitor is a 10V 1200uF Polarized Electolytic Cap. This is a filtering cap on the output side (5V). The other cap (much larger) is 400V 33uF...this is a noise filtering cap on the input side. (120V side)


Hello redhawk,

Thank you for the information! I will now scavenge some old motherboards for a 10V 1200 uF capacitor but in the meantime I have already place an order for a 5V 3A replacement PSU for my Asus router. Thanks for finding this issue and providing the needed pictures & information.
Sponsor
thx-1138
DD-WRT Novice


Joined: 18 Aug 2009
Posts: 24

PostPosted: Tue Aug 25, 2009 23:17    Post subject: Reply with quote
Hello hawkeye,

I can confirm your theory; Asus has definitely defective caps in their router PSU. Attached is a picture of my opened faulty PSU, the 1200uF 10v cap is bulged and no longer can function normally under stress (like when I was using my WiFi and/or have more than one Ethernet client connected). I recommend to add a step into the "peacock" instructions to visually inspect caps within a faulty router and troubleshoot potential faulty PSU if all other steps fails (re-set, re-flash, clear NVRAM, configuration settings, etc.). For me, problem has been solved by getting a replacement 5v 3A PSU; the router works 100%!



FAULTY ASUS WL-500G PREMIUM PSU AUG 2009.JPG
 Description:
Faulty ASUS WL-500G PREMIUM Power Brick. Check out the bulged 1200uF 10v capacitor.
 Filesize:  86.63 KB
 Viewed:  22222 Time(s)

FAULTY ASUS WL-500G PREMIUM PSU AUG 2009.JPG


KeithB
DD-WRT User


Joined: 22 Jun 2008
Posts: 479

PostPosted: Wed Aug 26, 2009 1:18    Post subject: Reply with quote
I repaired a co-worker's 12V/5V power brick for his USB external drive a few weeks ago. Same problem with Teapo capacitors, obviously bulging. I'm not terribly surprised to see power bricks with these problems, because they're usually sourced from the cheapest supplier in bulk anyway. I wonder if the infamous Netgear power brick problems are caused by under-spec and/or lousy quality and/or noisy capacitors also?
_________________
2x Asus RT-AC68U
redhawk0
DD-WRT Guru


Joined: 04 Jan 2007
Posts: 11335
Location: Wherever the wind blows- North America

PostPosted: Wed Aug 26, 2009 11:57    Post subject: Reply with quote
Thanx guys...KeithB you make a good point....with these router manufuactures and the "home" models....cheaper is better for them....but not for us in the long run.

I'll talk to Murrkf about adding something to the troubleshooting section of the Peacock....I'll also try to get something into our wiki for "Recovering from a Brick" page....but not today...I am off on a job this morning.

redhawk

_________________
I currently test dd-wrt on Asus, Buffalo, Linksys, and Netgear. Too many to list.

Looking for more test units (newer models) for the project...got a brick?...PM me to make a hardware donation. (USA) A donation is not a debricking service....it is a way to "Give back" to the dd-wrt project.

I do NOT provide personal assistance through chat or phone....so please don't ask.
Murrkf
DD-WRT Guru


Joined: 22 Sep 2008
Posts: 12666

PostPosted: Wed Aug 26, 2009 13:41    Post subject: Reply with quote
redhawk0 wrote:
I'll talk to Murrkf about adding something to the troubleshooting section of the Peacock....


Done.

_________________
SIG:
I'm trying to teach you to fish, not give you a fish. If you just want a fish, wait for a fisherman who hands them out. I'm more of a fishing instructor.
LOM: "If you show that you have not bothered to read the forum announcements or to follow the advices in them then the level of help available for you will drop substantially, also known as Murrkf's law.."
DaveMcLain
DD-WRT User


Joined: 12 Jul 2009
Posts: 82

PostPosted: Wed Aug 26, 2009 14:01    Post subject: Reply with quote
Electrolytic capacitors are generally the weak link in ANY electronic device where they are used. When repairing tube type guitar and hifi amps from the 1960's many times I've seen the original or very old tubes still working ok but the electrolytic caps in the power supply are dried up, leaking or shorted. Most of the time one of these components fails and it causes the amp to "blow up". Heat and voltage stress are the biggest enemies of electrolytic capacitors. If there were a way to get enough capacity in a small space for a small cost without using electrolytics reliability would go WAY up!
hpsenicka
DD-WRT Guru


Joined: 30 Jun 2008
Posts: 825
Location: near Toronto, Canada

PostPosted: Wed Aug 26, 2009 14:09    Post subject: Reply with quote
All electrolytic capacitors age..... 30 year old electrolytics are akin to a ticking time bomb... they will fail.

The problems with the premature failure of many "modern" electrolytics is well documented, and is basically due to manufacturing errors/defects and poor quality control.

Also, replacing bad caps with caps salvaged from other gear is not the ideal solution. Electrolytics are relatively cheap... buy some new ones!

Check out suppliers like Digikey and Mouser for Panasonic FC or FM series capacitors with the appropriate ratings.

_________________
WRT54G-RG
WRT54G-TM
WRT54GL v1.1
WRT54G v6, v8
WRT54GS v5
WRH54G
DaveMcLain
DD-WRT User


Joined: 12 Jul 2009
Posts: 82

PostPosted: Wed Aug 26, 2009 14:27    Post subject: Reply with quote
I'm sure that "cheap" caps are a big part of the problem. Also they are probably running them very close to "spec" voltage wise.
crashfly
DD-WRT Guru


Joined: 24 Feb 2009
Posts: 2026
Location: Sol System > Earth > USA > Arkansas

PostPosted: Wed Aug 26, 2009 16:29    Post subject: Reply with quote
I am surprised to see a thread about bad caps here at DD-WRT. I myself have run into several motherboards of various manufacturers that have had bad caps. In several instances, I have been able to replace the bad capacitors and replaced them with new ones. I still have one of those IBM computers today (Pentium 3). Those computers worked like a champ after caps were replaced. Only have a few that were not fixed by replacing bad caps.

Should anyone be looking for a good place to order capacitors from, I have been ordering mine from Mouser Electronics online. Caps will run you usually very cheap (so you can get many of them). They have multitudes of electronic parts. You will almost always be able to find what you need (especially if you have the exact specs).

This is just a kind of FYI thing. Hopefully it will help someone out.

_________________
E3000 22200M KongVPN K26
WRT600n v1.1 refirb mega 18767 BS K24 NEWD2 [not used]
WRT54G v2 16214 BS K24 [access point]

Try Dropbox for syncing files - get 2.5gb online for free by signing up.

Read! Peacock thread
*PLEASE* upgrade PAST v24SP1 or no support.


Last edited by crashfly on Wed Aug 26, 2009 16:30; edited 1 time in total
Radioman193
DD-WRT User


Joined: 16 Aug 2007
Posts: 487
Location: New York

PostPosted: Wed Aug 26, 2009 16:30    Post subject: Reply with quote
It dont matter what the Hardware is

HEAT is the MAIN Killer of your Capacitors changing the value of the Capacitor will NOT pervent this from happening again in time.

The "Dome" you see on the top comes from pressure inside the Capacitor as the liquid electrolyte gets hot and builds pressure inside .

99% of Capacitors fail cause of heat not cause of the value used or the circut thay are use in.

Example :
the bad "caps" you find in or on a motherboard are Mainly over by the Cpu regulators and Cpu.
And
Your power supplys by regulator heatsinks.

Just like in thx-1138 picture.

and not ALL "caps" that have a "Dome" are bad caps and still have the same value as stated caps are supose to VENT this presure but in most cases cant cause of the way thay are mounted .
a cap Vents off the presur out the bottom of the cap but if the sed cap is mounted firmly to the board it cant Vent so you get a "dome" on the top.
thay are supose to vent out the bottom the rubber seal or "plug" you see has a "Pinhole" in it to do Just this.
Thats why you NEVER mount a cap Tight to the board.
if you cant "wiggle" it or tip it side to side its way to Tight to the board!
And Dont mount a cap by a regulator heatsink if at all possible!

Thats why I say "The more amperage your power supply can provide the COOLER the power supply will run. "

http://www.dd-wrt.com/phpBB2/viewtopic.php?t=54242&start=180

and the caps on the router Main board SHULD be mounted with space UNDER the cap as you can see why...
Just look at the regulators arround the caps its a "HotZone".
if you mount them tight to the board the board will transfer the heat to the caps just that mutch more quickly and better !
Hence Hotter caps.

Cool



cap.jpg
 Description:
 Filesize:  92.28 KB
 Viewed:  22082 Time(s)

cap.jpg




Last edited by Radioman193 on Wed Aug 26, 2009 17:31; edited 5 times in total
Radioman193
DD-WRT User


Joined: 16 Aug 2007
Posts: 487
Location: New York

PostPosted: Wed Aug 26, 2009 16:54    Post subject: Reply with quote
kodo wrote:
Not to forget, not all bad Capacitors have bulge. I do much repair on mainboards and similar equipement and from time to time, we see bad capacitors which are simply dry without having a bulge. And not to forget, some of them have pressed out the rupper seal at the bottom. This can be easy overlooked Wink


Dry From venting and Heat.
KeithB
DD-WRT User


Joined: 22 Jun 2008
Posts: 479

PostPosted: Wed Aug 26, 2009 17:58    Post subject: Reply with quote
or dry because the electrolytic formula used was faulty/unstable in the first place.
_________________
2x Asus RT-AC68U
redhawk0
DD-WRT Guru


Joined: 04 Jan 2007
Posts: 11335
Location: Wherever the wind blows- North America

PostPosted: Wed Aug 26, 2009 18:00    Post subject: Reply with quote
hpsenicka wrote:
Also, replacing bad caps with caps salvaged from other gear is not the ideal solution. Electrolytics are relatively cheap... buy some new ones!


I agree new caps should be used when fixing power supplies and routers that are needed for a reliable network...but for my purposes (testing dd-wrt and not used in a true networked environment) changing out the caps with ones from an old (only 3 years) PC motherboard is the most efficient use of my time as opposed to waiting for parts to come in.

If it doesn't work, I just throw it away and connect things up to an old PC power supply with the enabler jumpered out. I have about 10 PC supplies laying around that have perfectly good 12V and 5V supplies in them. (depending on my needs)

redhawk

_________________
I currently test dd-wrt on Asus, Buffalo, Linksys, and Netgear. Too many to list.

Looking for more test units (newer models) for the project...got a brick?...PM me to make a hardware donation. (USA) A donation is not a debricking service....it is a way to "Give back" to the dd-wrt project.

I do NOT provide personal assistance through chat or phone....so please don't ask.
Radioman193
DD-WRT User


Joined: 16 Aug 2007
Posts: 487
Location: New York

PostPosted: Wed Aug 26, 2009 19:13    Post subject: Reply with quote
KeithB wrote:
or dry because the electrolytic formula used was faulty/unstable in the first place.

Heat will change the "Formula" or the mixture.
it is a Basic Mixture .

"aqueous electrolytes" use water and Steam off when hot . = DRY
and are known as "cheep" caps.

"non-aqueous electrolytes" consist of a weak acid and handle heat Alot better a salt of a weak acid and a solvent.
The solvent is generally one of the polyhydroxyl alcohol group such as a glycerol or glycol although in some cases it may be replaced with the use of a hydroxy alkylamine.
The salt of the weak acid is generally a salt of the weak acid employed although this is not necessarily always true.


In some cases the electrolyte may not employ a solvent but may consist of two salts only, in its composition.

"Non-aqueous electrolytes" may also contain inert filler materials, for the purpose of increasing viscosity, such as bentonite, diatomaceous earth, silica gel, aluminum oxide, agar-agar, gum tragacanth and starch.
In some instances, inert substances are added to the electrolyte for the purpose of increasing electrical conductivity.
Such substances may be magnetite, graphite, colloidal graphite, carbon, colloidal silver or powdered metals such as aluminum and copper.

Hence that Bad Piss like smell you smell when one blows up .


Physically, the non-aqueous electrolytes may, and do range from slightly viscous fluids to semi-hard or states


Cool
Radioman193
DD-WRT User


Joined: 16 Aug 2007
Posts: 487
Location: New York

PostPosted: Wed Aug 26, 2009 20:24    Post subject: Reply with quote
That reminds me of when i was 8 years old

I use to build "Bombs" out of 4 - 40v DC, 2 to 10 farad Capacitors wired in parallel hooked to an Long extension cord to the garage were we had a Outlet that was on a switch.
we would plug the cord in and "Hit the switch"

WOW

What a BANG!!! Laughing
and a BIG Hole in the Yard :D

These caps were 6 inches in dia. and 10 or 11 inches tall.
Goto page Previous  1, 2, 3, 4  Next Display posts from previous:    Page 2 of 4
Post new topic   Reply to topic    DD-WRT Forum Forum Index -> Broadcom SoC based Hardware All times are GMT

Navigation

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum