[dunhill]

In our "nest" of >25 , in static WDS connected, WRT54G(S) we got after a few months problems.

Symptoms like RX or TX only, very low RX/TX, speeds stay at 1Mbps, and other strange behavior.
After unsuccessfull searches over the internet we started our own "investigation"

A)
The most problems came from units connected to open dipols and/or high gain omni directional antennas
in those units we found the chip [S79} was defective, that is the first small black chip that you encounter when you follow the antenna lines/wire.

B)
Other problems, on all units, was another [S79] chip , located inside the RF housing
(follow the line from the first chip into the metal case and there it is.)

==>>==

How did we detect those errors?

in case of A:

connect an antenna to 1 connector only

Open 2 tabs in a browser
(replace 192.168.1.1 by the IP address of your unit)

open in one tab http://192.168.1.1/Wireless_Advanced.asp
set the rx and tx antenna to 1 side only (left or right)
click on the [save] button

in the second tab http://192.168.1.1/Site_Survey.asp
look at the strenght of other units in your neighbourhood
change the antenna to the other plug
look again at the strenght of other units in your neighbourhood
if you see no big changes, the [S79] is broken

open the tab with http://192.168.1.1/Wireless_Advanced.asp
set the rx and tx antenna to the other side only (right or left)
click on the [save] button

goto the second tab with http://192.168.1.1/Site_Survey.asp
look at the strenght of other units in your neighbourhood
change the antenna to the other plug
look again at the strenght of other units in your neighbourhood
if you see no big changes, the [S79] is broken

else the 1st [S79] looks fine.

------------
in case of B:

With a multimeter test if there is a 2.4 (+/-) volt on the copper lane that leaves the RF housing.
This copperlane will connect to a Capacitor, here you can test the voltage.
If there is no voltage, or the voltage lower than 1.5 volt, you can say goodbye to the [S79] inside the RF unit.

==>>==

What did we do to "protect" our units?
Probably most of you don't have the "extreme" conditions that we have here in the Dominican Republic.
A moisture level of 80% is "normal", than we have those suddenly growing tropical thunderstorm that fills the air with electricity, and this will be "carried" by the moisture to "burn the unit".

The original model 1.xx units, had some protection, there was a 100ohm resistor in the antenna line, the newer models don't have them, and the version v5 models even have the capacitors in that same antenna line removed.

org: RFunit - C - S79 - C - R(to ground) - C - C(to ground) - antenna connector
V2/3: RFunit - C - S79 - C - C - antenna connector
V5: RFunit - C - S79 - C - antenna connector

To give a bit of protection (from the statics caught by the antenna), we put on the place where the original 100ohm resistor is placed, a coil, 2 windings on 1.5mm

WARNING !!
A very handy person is able to remove/(re)place the coil and/or the [S79]
A novice better not even start to think about it
And you will loose your warranty.

BUT
Linksys notified us that they cannot provide the [S79] chip (after multiple emails) and they stated "we don't know, where to get them or who is the manufacturer of the boards".

So we started to "collect" [S79] chips since the [S79] in the antennaline is not really necessary if you use only 1 antenna.
This chip can be removed and replaced by a bridge to only 1 antenna connector
Conclusion is that if the first [S79] chip is burned, you only have to remove it and replace the chip by a bridge.

Replacing the [S79] inside the RFunit is a bit more difficult, but can be done

After replacing the chips and placing the coil, we cover the coil with hotglue, to protect it from unwanted movement, and we put the whole antennaline and the [S79] chip inside the RFunit is a plastic coating(spray) to protect it more or less from the statics that travels on the moisture.

3 heavy thunderstorms later we had only 1 damaged unit, but that was not so strange when the lightning struck a building less than 100 meters away.

And ofcourse all the units have heavy heatsinks on the chips that will be hot and we don't (cannot/willnot) power up over 100mW.

A.

[wlan]

Thanks a lot. It's seems that my WRT54G 2 with 13dBi omni is with damaged S79. I have sometimes slowdown speeds to 1 Mb, but not always. Also, the upload is OK through days, and terrible through the nights. But download is always Ok. It's seems I must replace this unit...

[Sailor]

This has come up before, only solution was a chip inductor. See post in old forum:

http://forum.bsr-clan.de/viewtopic.php?t=5796

[azyx]

The S79 chip is AS179-92 chip by skyworks
http://www.skyworksinc.com/products_display_item.asp?did=612#search=%22AS179-92%22
The same switch uses awl200 mini-pci prism 2.5 card

[npero]

[dunhill]

thanks for the manufacturer info, i ordered a 100, that will save me some time
I also found that specific article, but i think this is a bit more enhanced

Arjan

[riku2015]

Hi thanks for info.
I have 4 WRT54GL:s broken.
Also GL version have this problem.
i will send to warranty and pray they give a new one

Anybody knows if the Buffalo WHR-HP-G54 OR WHR-G54S have same issue?
Or any other device?
Brainslayer maybee know?


Please i need answers, im going to change all omni ap:s to get rid of this problem.

[riku2015]

looks like buffalo WHR-HP-G54 have this same problem.
static esd, even with no thunders or lightnings that broked router. need to send that to warranty.

that was 4 or 5 router to broke up in the same place. next i will change antenna, but i doubt that is not issue.

maybe Brainslayer can help with this ?

anyone have better options to resolve this? another router?
this is a problem only in a weak signals. those who use ap:s with a strong signal, they don't even know if that is broken or not.

[dunhill]

The main problem lies in the type of antenna

OmniDirectional are mostly build from open dipols, those antenna's grab the highest static volume in the air, even the so nice added Lightning protection is way to slow to protect your unit from that.

Most Panel or directional antennas have a ShortCut dipol in it, Statics have almost no influence.

Long cables are also nice static collectors, i have no idea why, but i see people running 20m of cable or more (think of the amazing losses) and those cables work as antenna as well.

Protection inside the unit is not a 100% garantee of no damage, but at least it does (for me) 80% of the job.

[riku2015]

hi dunhill, thanks for answer.

Lightning protection is not the solution.
i have added that with ground wire. still it blows linksys and buffalos..
also cable is maxium lenght what it can take, about 3.5meters rg-213 low-loss cable. so cable is not issue

i don't know if the buffalo have same diversity chip, but looks like. (i never opened it, it takes warranty)
also in the same mast have yagi(home made) it's short circuit dipole, that never broked the AP.
exept one issue it's broked... other mast.

only omni brakes, it's dlink omni-antenna 6 or 8 dbi i don't remember.
i was thinking are interline omnis suitable for that use? can it be seened with multimeter or something if antenna is suitable? i have those omnis still at our storage.

any other solution, like other ap?
minium requirements:
- runs dd-wrt of course
- have RP-SMA or RP-TNC connector for external antenna.
- runs 5volts or 12volts.
- it's G- compatible 54Mbit/s
- can handle 10 clients

thanks already for answers.

[riku2015]

can anyone please confirm buffalo WHR-HP-G54
chip number IC 12 is diversity chip, and what type is it? also can anyone confirm that is not protected to ground?

source:
http://img114.imageshack.us/my.php?image=whrhpg544hf.jpg


and can anyone confirm the whr-g54s also have same chip? BUT IT HAVE PROTECTION???
http://img122.imageshack.us/my.php?image=whrg54s8oy.jpg
i see in that picture resistor at side rp sma connector.
does this buffalo whr-g54s blow at ESD/STATIC? need to test anyway it's about 50-55eur.

[dunhill]

[riku2015]

someone who has opened buffalo may confirm this. thanks already.

[riku2015]

now it's sure that WHR-HP-G54 is also ESD fragile

second WHR-HP-G54 is now broken. after 3 days.
even no heavy thunder storm.

next the whr-g54s. problem is 3,3v need to improvise something.
maybe change in weekend.

[dunhill]

To make something clear:

You don't need a thunderstorm to have static electricity in the air !!!
===================================================

We just replaced a unit that was connected to a NetGear 14Db panel connected to a buffalo, this panel is one build based on an open antenna structure, result: the S79 (both) are burned
Both means there is no 3.3Volt between C64/IC10 and the Ground, than you can be 100% sure that IC12 is dead as well

My solution that i am going to do with this unit:
Remove IC 10 and 12
make a bridge on the IC12 place between C64 and C50 or C72, i just need ti find which one is connected directly to the antenna connector
Replace IC 10
Put a coil in the antenna line between C50 or C72 (see above) and the Ground

Same idea as in a WRT54

A.