Advice on replacement caps for Netgear WNDR3700

[Ascaris]

Hi everyone,

My (formerly?) trusty Netgear WNDR3700v1 router, which I am thinking I bought in about 2007 or 2008, is slower than it should be in wireless throughput, and it seems to be getting worse. I hadn't noticed when I was just browsing the internet, as my internet is still slower than even the anemic speed the router can muster. Recently, though, I have been trying to set up a PC as a NAS for backup purposes, and the slowness of the 3700 became evident. The 3700 was half as fast in actual throughput as my D-Link DIR-825 (even older but with far fewer hours on it) despite the same connect speed (300mbps under 40Mhz wireless-N on 5Ghz band) and all the same settings, and when I flashed it to DD-WRT, it slowed by half again, no matter what settings I tried-- and that persisted even after I went back to the Netgear firmware using the same settings as before.

After a helpful person over on the Netgear forum got me on the "failing hardware" track (I was so busy trying to find a firmware issue, given the 3700's history of having buggy firmware, that I couldn't see the forest for the trees), I opened it up and found this. I also posted this link on the Hall of Shame thread if it looks familiar-- I hope this isn't a problem, but it is pertinent to both:



The upper left and lower right image are the same capacitor from different angles so that all of the markings are visible. The lower left (10mm) capacitor looks okay (there are only four capacitors inside there, so I just photographed them all). The three 8mm caps are all the same as each other.

My question: Does anyone know what the text on the caps (other than the obvious, like the microfarad, temperature, and voltage ratings) means? Is this model a low ESR cap? If it is not, would it be a bad idea to replace them with a low ESR type such that badcaps.net sells?

Thanks!

[stj]

Re: Advice on replacement caps for Netgear WNDR3700

i cant see any pictures attached.

btw, you may want to flash it with something more interesting than the factory crap.
http://www.gargoyle-router.com

[linuxguru]

Re: Advice on replacement caps for Netgear WNDR3700

Yup, those are LTEC LZG, which are claimed to have low ESR. Various replacements are possible, including durable Rubycon ZL/ZLH/ZLG.

[mockingbird]

Re: Advice on replacement caps for Netgear WNDR3700

My question: Does anyone know what the text on the caps (other than the obvious, like the microfarad, temperature, and voltage ratings) means? Is this model a low ESR cap? If it is not, would it be a bad idea to replace them with a low ESR type such that badcaps.net sells?
Thanks!

You will need 3 16V 470uF capacitors in 8mm, and one 25V 470uF in 10mm (I think they are all 15mm in height, judging from the pictures). I just checked the badcaps store and I couldn't find what you needed.

If you're comfortable with it, I might also recommend opening up the AC adapter and changing the caps inside of it too.

If you need help finding replacements, let me know.

[Ascaris]

Re: Advice on replacement caps for Netgear WNDR3700

You will need 3 16V 470uF capacitors in 8mm, and one 25V 470uF in 10mm (I think they are all 15mm in height, judging from the pictures). I just checked the badcaps store and I couldn't find what you needed.

I saw this one, which seems to be a match for the 16v:

https://www.badcaps.net/store/produc...roducts_id=148

It is a little shorter than the Ltecs (they measure 16.5mm from the top of the cap to the PCB surface), but if the specs are right, that should not matter, right?

The 25v one isn't there.

If you're comfortable with it, I might also recommend opening up the AC adapter and changing the caps inside of it too.

If it can be opened-- it is a wall-wart type, and it might be one of the completely sealed ones. Is the concern here ripple? I can test it for voltage, but I do not have an oscilloscope to look for ripple. It's probably not that expensive to replace if it comes to that.

If you need help finding replacements, let me know.

I would welcome that; thanks. I can match size, voltage rating, microfarad rating, but my knowledge ends about there.

[mockingbird]

Re: Advice on replacement caps for Netgear WNDR3700

I saw this one, which seems to be a match for the 16v:

https://www.badcaps.net/store/produc...roducts_id=148

It is a little shorter than the Ltecs (they measure 16.5mm from the top of the cap to the PCB surface), but if the specs are right, that should not matter, right?

The 25v one isn't there.

I don't want to detract from Topcat's business (to the contrary, it's always the first place I check when referring people here), but eventhough it would probably work, it's not the best idea, considering that Ultra-Low ESR caps like Nichicon HN sacrifice longevity for performance. So you can get something else much more suitable for this application.

If it can be opened-- it is a wall-wart type, and it might be one of the completely sealed ones. Is the concern here ripple? I can test it for voltage, but I do not have an oscilloscope to look for ripple. It's probably not that expensive to replace if it comes to that.

Yes. If the caps in the adapter are defective, then they pass the ripple to the caps inside the router. You can buy a new one, but make sure the new one is at least of equal quality and has a recent manufacture date. Adapters that sit in storage with poor quality caps can theoretically be as inferior as ones that have been in service. If the adapter is of equal quality but was recently manufactured, then you should be able to get at least a few years out of the caps in it, even if they are second or third tier.

As for opening them -- yes, they're typically sealed, and I've personally re-capped many D-LINK adapters. Like I said, it depends on the type of person you are.

I would welcome that; thanks. I can match size, voltage rating, microfarad rating, but my knowledge ends about there.

Sure, always glad to help . Which company are you planning on buying from?

[Ascaris]

Re: Advice on replacement caps for Netgear WNDR3700

I am open to suggestions on where to get them. I've been looking at the options on Mouser's site... I plugged in the 470 microfarad, 16v, 8mm, and there were still 179 listed! I have no experience with which places are the best; obviously, I would go to badcaps.net first too, since they are good enough to offer this useful forum here, but other than that, I am open.

Since I am on the brink of ordering some caps, I thought I would also go open my defunct LG (LCD) monitor, and what do you know, it has 2 bulged Su'scon caps. I've suspected the caps on that for a long time (I've been visiting this site as a guest for reference for a while, so I've read a lot of the stuff here), and while I don't (of course) know that the failed cap replacement will fix it, it's worth a try. I just posted a pic of the two bulged caps to the hall of shame... those consist of one 18mm in diameter, five 10mm (two bulged), one 8mm, one 6mm, and four 5mm. I would appreciate opinions on these too. They're Su'scon SGs. Should I start a new thread?

Thanks!

[mockingbird]

Re: Advice on replacement caps for Netgear WNDR3700

Nah, you can list them here and I can check those too, no problem.

But list them like this please:

1) "Voltage, Capacitance, Brand, Series, Diameter (width x height)"
2) etc...

Hopefully I'll post the parts from Mouser sometime this weekend then.

Cheers and good luck.

[Ascaris]

Re: Advice on replacement caps for Netgear WNDR3700

The two bulged caps are in the secondary side of the PSU board inside the monitor. I'd like to just replace all the secondary side caps, given that this is where the failures were and where the most load on the caps is (AFAIK). I know a lot of people here can R&R dozens of caps and think nothing of it, but for me, this feels like a daunting task (I have never been all that great at soldering, but given how often electronics failures can be traced back to these caps, I would like to learn)...

They are:

35v, 470µf, Su'scon, SG, 10mm x 20mm (three of these)
16v, 1000µf, Su'scon, SG, 10mm x 20mm (two of these)

Thanks!

[mockingbird]

Re: Advice on replacement caps for Netgear WNDR3700

For the router
16V 470uF cap in 8mm:
http://www.mouser.com/ProductDetail/...50ELL471MH15D/

25V 470uF cap in 10mm:
http://www.mouser.com/ProductDetail/...50ETD471MJ16S/

For the LCD

1) http://www.mouser.com/ProductDetail/...50ELL471MJ20S/
2) http://www.mouser.com/ProductDetail/.../EEU-FR1E102E/

Good luck and please report back.

[Ascaris]

Re: Advice on replacement caps for Netgear WNDR3700

It's alive!

(I bet tons of people have said that here. Ah well, it's what I was thinking, even if it is trite.)

I ordered the caps the day Mockingbird posted the links, and they arrived today. It was easier than I thought, though I definitely want to get that desoldering iron from Radio Shack or something like it.

Wireless speeds are back up to where they should be... looks like a success!

Here is a quick pic I took with the new caps in before I closed it up. I didn't worry about the depth of field; I was eager to try it out.

Next: the monitor!

[mockingbird]

Re: Advice on replacement caps for Netgear WNDR3700

Congratulations!

Those caps are rated for something like 10,000 hours, so I hope you get all you can out of it

[Ascaris]

Re: Advice on replacement caps for Netgear WNDR3700

After my experience recapping the router, I didn't want to attack the monitor without a means to desolder. I went to Radio Shack and bought a solder sucking bulb, then returned home and got started.

I got the old caps out without issue, but there were large sheets of solder on the PCB, and things were much closer together than on the router board. I managed to accidentally touch the tip of the iron to one of those sheets, and I was afraid the resulting mess had shorted something, but after examining the traces, I could see that what had been bridged was supposed to be anyway, so onward!

Got it all done; here is the picture:


Buttoned it all up, got out my fire extinguisher just in case (that's the confidence I have in my abilities), plugged it in and... up came the LG splash screen. It works! It was bricked before (do people use that term with monitors?)... no lights, no anything before.

Thanks much to you, Mockingbird! I appreciate the help selecting the caps and steering me the right way.

One thing though-- why does my new soldering iron look like this? Did I do something wrong, or is it a manufacturing defect in the tip? It's a 40w Weller. I already had a 25w (also Weller), but the guide here said to use a 60w preferably and no less than a 40w for removing the caps... and 40w was the highest Ace hardware had that was not intended for plumbing, so that is what I bought. It worked very well.




Thanks!

[Sparkey55]

Re: Advice on replacement caps for Netgear WNDR3700

After my experience recapping the router, I didn't want to attack the monitor without a means to desolder. I went to Radio Shack and bought a solder sucking bulb, then returned home and got started.

I got the old caps out without issue, but there were large sheets of solder on the PCB, and things were much closer together than on the router board. I managed to accidentally touch the tip of the iron to one of those sheets, and I was afraid the resulting mess had shorted something, but after examining the traces, I could see that what had been bridged was supposed to be anyway, so onward!

Got it all done; here is the picture:


Buttoned it all up, got out my fire extinguisher just in case (that's the confidence I have in my abilities), plugged it in and... up came the LG splash screen. It works! It was bricked before (do people use that term with monitors?)... no lights, no anything before.

Thanks much to you, Mockingbird! I appreciate the help selecting the caps and steering me the right way.

One thing though-- why does my new soldering iron look like this? Did I do something wrong, or is it a manufacturing defect in the tip? It's a 40w Weller. I already had a 25w (also Weller), but the guide here said to use a 60w preferably and no less than a 40w for removing the caps... and 40w was the highest Ace hardware had that was not intended for plumbing, so that is what I bought. It worked very well.




Thanks!

The pitting of the soldering iron is caused by the action of soldering itself. Is is normal. You are creating a mixture of lead, tin, copper and other lesser metals in the alloy. Using a brass tip will reduce this effect a little.

[stj]

Re: Advice on replacement caps for Netgear WNDR3700

that should read a brass tip cleaner.

the advice about 40-60w is for pc motherboards,
i would advise a programable temperature iron rather than stating a wattage.

[Sparkey55]

Re: Advice on replacement caps for Netgear WNDR3700

that should read a brass tip cleaner.

the advice about 40-60w is for pc motherboards,
i would advise a programable temperature iron rather than stating a wattage.

You are wrong. tip cleaning has nothing to do with what I am talking about. A solid brass tip will not be as active electro-chemically as a solid copper tip, thus less tendency to dissolve some of the metal into absorbtion of the solder alloy.

[stj]

Re: Advice on replacement caps for Netgear WNDR3700

a copper tip will almost 100% be iron-plated.

[Sparkey55]

Re: Advice on replacement caps for Netgear WNDR3700

a copper tip will almost 100% be iron-plated.

I fabricate my own tips out of solid copper, no steel or iron at all. They work just fine as do the brass tips that I make.

[Ascaris]

Re: Advice on replacement caps for Netgear WNDR3700

It is plated, but that happened anyway.

Is it reasonable for the tip to be in that crappy shape after only two uses? They ought to include 30 extra tips in the blister pack if so...

[Sparkey55]

Re: Advice on replacement caps for Netgear WNDR3700

It is plated, but that happened anyway.

Is it reasonable for the tip to be in that crappy shape after only two uses? They ought to include 30 extra tips in the blister pack if so...

What type solder are you using? I always use a homebrew heat controller on my irons so as not to burn them up when the full amount of heat is not needed.