Linksys BEFSR41 Router Capacitor Solution

[Krankshaft]

Well my old reliable Linksys BEFSR41 router just disconnected me again this morning the red diag light was on and as usual when this happens I just unplug it and reconnect it and I'm good to go for some undetermined amount of time until it does this again.

It could be a week 2 or a month I don't keep track.

However recently I assembled my new shiny Blue Anatek / Bob Parker ESR meter (I will have a full review in the test equipment section next week boy was assembly and problems that weren't there caused by the "diagnosis function" time consuming).

Anyhow so I open the case to open it is easy there are no screws simply grasp one of the blue legs and one of the black ones and pull apart real hard and the front of the case will release from the back.

Remove the single screw securing the board to the bottom casing and push the board back to disengage it from the 4 retainer tabs.

The D-Paston caps inside all looked fine with no bulging.

So I get my ESR meter out and measure the low value 10uf 16V caps and this is what I find.

There are 15 10uf 16V in all I only listed the ones with ESR greater than 3.0 ohms.

70 ohms
24 Ohms
15 Ohms
12 Ohms
11 Ohms
8.0 Ohms
8.0 Ohms
5.6 Ohms
5.3 Ohms

These measurements were made out of circuit after they were red flagged when I measured them in circuit.

No thats not a mistype one was actually 70 ohms.

I replaced all of these with General Purpose 105 C Chemicon KMGs.

The 2 1000uf 16 Volt filter caps measured as follows:

.14
.32

I don't think that they were a real problem but since they were an unknown (D-Paston) I replaced them too.

I used low ESR Panasonic FCs since those caps were part of the filter network and I upgraded the working voltage to 25V for a little more "elbow room" especially since the wall wart linear adapter isn't regulated.

This is the very reason why I don't believe that caps under "insert value here uf" usually don't give you any trouble and you can leave them alone.

The faulty caps on this board looked just fine to the eye but one of those "ok" caps had an ESR of 70 ohms .

I say let your ESR meter be the judge.

Here is a pic of the finished board I had to mix 63 volt 10 ufs with 100V 10 ufs (thats why they are different sizes) because I was running out of Chemicons at 10uf I have to reorder .

I must say it felt wierd not having Internet access while recapping I wanted to check out D-Paston but I couldn't it also reminded me not to screw up .

[Krankshaft]

Re: Linksys BEFSR41 Router Capacitor Solution

On a related note does anyone know who this D-Paston is?

I have never seen them before.

[zandrax]

Re: Linksys BEFSR41 Router Capacitor Solution

I think a minor brand: I've found three japanese pages about capacitors, D-Paston seems connected with taiwanese Her-Mei Ltd, whose site is reacheable only in the Web Archive depot.
If Google translator is faithful enough, these are bad caps.

Link:
1) brands list, logo and site [and translation]:
http://bb861861.blogspot.com/2007/04/blog-post.html
http://www.google.com/translate?u=ht...&hl=en&ie=UTF8

2) generic page about capacitors:
http://www.geocities.co.jp/SiliconVa...er/sentaku.htm
http://www.google.com/translate?u=ht...&hl=en&ie=UTF8

3) caps' vents and manifacturers. Overseas manifacturers means "outside Japan":
http://mkk.s20.xrea.com/cap.htm
http://www.google.com/translate?u=ht...&hl=en&ie=UTF8

4) old Her-Mei site (seems disappeared since 2005):
http://web.archive.org/web/*/http://...om.tw/english/

BTW, Her-Mei site refers to Asiacom and Iwill brands: do Iwill boards mount this crap-acitors?

Zandrax

[gonzo0815]

Re: Linksys BEFSR41 Router Capacitor Solution

This is the very reason why I don't believe that caps under "insert value here uf" usually don't give you any trouble and you can leave them alone.

Well i think this rule of thumb is based on more sophisticated knowledge then the assumption, that small values caps can`t go foo.bar.

Especially on motherboards, small value caps are mostly not used in critical places.

So even a high ESR would not do that much harm.
This rule of thumb was never indented as a 100% success guaranteed solution. The pro will fix the big ones, if trouble remains the small one too.

For DIY i think there is little discussion, that a full recap down to the smallest cap would be the "ideal" choice (as long as soldering Skills & equipment pose no risk for every other solder point ... )

Personally, i have only replaced the big input and output caps on my BEFSR41 and i have no problems up to now.


I have to admit, i only are using it as a switch. I may replace the smaller caps too if i am bored someday ;-)

The problem with the smaller caps could be a issue with all the other common network devices like switches etc.
May be i recap all my switches, as my DSl connection has to pass 4 switches till my box.
All big caps are already replaced, due to stability problems.

[Krankshaft]

Re: Linksys BEFSR41 Router Capacitor Solution

Thanks for reminding me I need to recap my D-Link 16 Port switch the Linksys goes directly into it which my box then plugs into I checked it out some time ago and it has G-Luxons in it .

No problems with it yet but I'd rather not wait for it to take a dump like the Linksys.

Its good news that the Hermei site is down hopefully they're out of business they deserve it for making their crap caps under both the Hermei and the D-Paston name.

I'm hoping that they didn't change their name to something else.

On a related note has anyone ever found a router or switch with good caps in it?

Since Linksys has been owned by Cisco for some time have their caps improved or does Cisco use crap caps just like Linksys did?

[Logistics]

Re: Linksys BEFSR41 Router Capacitor Solution

These routers are notorious for having the main power caps fail, especially the one nearest the power jack. My BEFSR41 did exactly the same trash, and I noticed the big 1000uF nearest the power jack got REALLY HOT, and it actually was starting to bulge on the bottom, with a tiny bit of electrolyte leakage. I replaced it with a Jamicon 105c and it was fine. I've since replaced both the big 1000uF's with Panasonic FM's, but it didn't have ANY problems after the first replacement. Again, they get HOT! I also put a heatsink on one of the IC's because it got untouchable-hot. These things are a cooling nightmare and I just leave the thing apart, with only the base attached to the PCB and some spacers. They just run too hot.

[PedroDaGr8]

Re: Linksys BEFSR41 Router Capacitor Solution

a lot of people put fans in these Linksys routers. I have one in the WRT54GSv2 at my parents office. I got a small 40mm fan with integrated heat sink and installed it on the router (just attached the leads to a power lead and ground lead) and the put heatsinks on all of the other major chips that I could see including the whole power section. The end result? it ran much more stable with overclocking (no biggie) and just in general more stable. As in current run time without a restart is over a year now. (Running DD-WRT on it by the way

[gonzo0815]

Re: Linksys BEFSR41 Router Capacitor Solution

I have put a few passive HS in my wrt54g and sure it is fully recaped.
The most important step regarding stability, working QOS and bandwidth limiting was the switch from dd-Wrt to Tomato.
Sure, Tomato does not have that much features like dd-wrt, but in the end QOS and stability was the more important thing for me.

[MD Willington]

Re: Linksys BEFSR41 Router Capacitor Solution

Hmm... maybe time to recap my router...

[Yatti420]

Re: Linksys BEFSR41 Router Capacitor Solution

HI All,

I have dissembled my Linksys BEFSR41v2 to find the same D-Paston caps installed.. Currently when I plug in this router it does not leave diagnostic mode. When you get close to it you can hear a low audible electrical buzz. After inspecting the board I could only visually see 1 bulging on top - D-Paston cap located closest to the power jack.

I was planning on replacing the D-Paston caps but I thought of posting here first to get a second opinion.

Could the electrical buzz sound be a sign of more serious problems? Should I go ahead and replace the caps and see if it works out? Any other part causing this?

Attached is a picture of the bulging cap from above..

[starfury1]

Re: Linksys BEFSR41 Router Capacitor Solution

well don't know the caps but probably crap

I would replace those 2 caps pictured and possibly any others around the size
(with vents)
the smaller ones are normally not to much to worry about even if crap.

at a guess I say the bulging is your problem and provided it hasn't caused any other damage it should be OK.

From what I can tell it looks like the plug pack is AC (secondary) and there is a bridge rectifier on the PCB
That popped cap is the Filter cap for the Bridge rec ...so thats probably the buzzing you can hear is the mains frequency.

It appears to be a linear supply so no need to get super low ESR type caps but make sure it a quality brand cap

not sure off hand which series would be best suited to this
panasonic FC or ruby ZL (probably a little over the top)
but should work no worries.

what you get may depend a little on whats available to you in your area
most Internet places etc ship but the cost will be more then the caps.

If what I suspect above is wrong and it is a switcher of some kind (doubt it)
that series would most likely be OK anyway.

photo is a bit blurred so cant read any details

chances are thought replace that cap and it will work ok

if you got a General purpose type cap of that value or a little bigger same voltage you can use that for a test.
Then do a proper repair once you know its working.

you will of course need to know how to remove a cap and solder.
if not check FAQ section and practice on junk pcb before hand.

lastly these types of caps are polarized so make sure positive goes to positive or you can kiss the cap goodbye.

HTH
Cheers

[starfury1]

Re: Linksys BEFSR41 Router Capacitor Solution

quick look seem like theres enough info in the above posts to work through
so yeah Id replace both if it was me and I possibly take the I/P cap to 25V
slight amendment on the smaller caps... yeah mostly not, but can be

HTH

Cheers

[kc8adu]

Re: Linksys BEFSR41 Router Capacitor Solution

that one is after the bridge and is likely the problem.
dpaston is a known crapcap.

[Fizzycapola]

Re: Linksys BEFSR41 Router Capacitor Solution

Linksys routers in general are notorious for having faulty capacitors. Even if they work, they probably won't work at their best.

Particularly the smaller capacitors have been recognised as partially failing and causing serious problems like intermittant LAN disconnections. Such small capacitors tightly packed were impossible to grip by hand, I used a high tension alligator clip to wiggle them out whilst adding solder generously to the other side. Replaced with Rubycon YXA.

After partially trying Nichicon HD, Sanyo Oscon SP and Panasonic FM. I settled that Panasonic FM gave the best and most consistent throughput.

My Linksys recap and modification so it is cool the touch even when fully cased is here: https://www.badcaps.net/forum/showthread.php?t=5090

The total weight of copper heatsink required to passively cool the core I would estimate at no less than 150 grams. Maybe less if the heatsink is designed for passive cooling ( i.e cross cut fins instead of straight) . As these routers have no useful vents adding some maybe good to keep the plastics cool the the touch aswell. The metal parts of old umbrella's fit perfectly over the plastic edges when cut to give a professional industrial looking finish. Old umbrella's can be found for free in any town in a few minutes on a bicycle.

On buzzing, if it's particularly loud, random and annoying this is a known manufacturing defect with some of the Linksys routers that shouldn't have got on the market, indicative of a faulty router, should be sent back for a silent replacement. My buzzing one still would drop ADSL occasionally (my long distance to the exchange adding justification to this - though other brands such as Billion and TP Link don't drop even at higher attenuation and offer higher bandwidth) even after recapping showing it cannot be solved easily if you are lumbered with an inherantly badly manufactured buzzing one.

On the note of unscrewing the router, my identical case one has 2 small screws under the two front feet rubber pads. It surprises me that this identical one doesn't have these screws, I know brute force will open the router though as the screws are very small and only attached to a thin slither of plastic of the rear section.

[Yatti420]

Re: Linksys BEFSR41 Router Capacitor Solution

Back all,

Thanks for the replies & tips... This is pretty much my practice board so I am not to concerned about messing it up...

The buzzing is sort of loud... The router did last about 4-5 years through some pretty good abuse... It could be faulty though.. I have a good "BEFSR41v2" that I acquired recently with a different setup checked both power supplies everything seemed fine.. I pulled the 2 big D-Paston 1000uf 16V 105C caps today.. Will be getting replacements soon...

On a side note if I do manage to get it working again, if I were to place a passive heat sink on an IC how is it "stuck" there? Is there a type of thermal glue compound, or is it custom mounting?

Thanks..

[starfury1]

Re: Linksys BEFSR41 Router Capacitor Solution

On buzzing, if it's particularly loud, random and annoying this is a known manufacturing defect with some of the Linksys routers that shouldn't have got on the market, indicative of a faulty router, should be sent back for a silent replacement.

Interesting, I sort of vaguely remember something about that...did we have a thread it was mentioned before ?

Was the actual cause known?

I don't know on the thermal clue stuff but yeah I think thats the case
FizzyC or others here could tell you what it is or what its about I guess.

just so you know Yatti420 Panasonc FM has better specs then the FC series.

some better ventilation wouldn't hurt thought thats for sure.

FizzyC from posts has some first hand knowledge of these things, I dont
Most stuff I got is linksys but hasn't failed in a big way yet!

Cheers...keep us posted


Cheers

[zandrax]

Re: Linksys BEFSR41 Router Capacitor Solution

@ Fizzy: I heard of Linksys routers with bad caps (yours, pentium's and others), Linksys EM emissions disturbing Ham radios and noisy psus in some Linksys gear, but I never found that buzzing Linksys are defective and should have been recalled: can you explain this a bit?

TIA

Zandrax

[kc8adu]

Re: Linksys BEFSR41 Router Capacitor Solution

@ Fizzy: I heard of Linksys routers with bad caps (yours, pentium's and others), Linksys EM emissions disturbing Ham radios and noisy psus in some Linksys gear, but I never found that buzzing Linksys are defective and should have been recalled: can you explain this a bit?

TIA

Zandrax

his router is buzzing due to an open filter cap after the bridge.
it will stop after recapping.
btw a neighbor had an old linksys router.
it made racket on 2m ssb here.but it would stop as soon as i transmitted.
turns out my rf would get in it and lock it up.
they told me about it going bad about the time i tracked it down to their place.
they got a dlink and no more problems.

[gonzo0815]

Re: Linksys BEFSR41 Router Capacitor Solution

A simple common mode choke and may be a full EMI filter would certainly solve this issue with your neighbors problems.

At least if the problem is caused by the buck converter and not from the 100Mhz network chips.

At least my Wrt54g v2.0 does have some very small HF coils, but certainly there could be a little more EMI filtering in the range of the switching frequency.

[zandrax]

Re: Linksys BEFSR41 Router Capacitor Solution

his router is buzzing due to an open filter cap after the bridge.
it will stop after recapping.

Thanks Kc8

Zandrax