WRT54G fried - plugged AC into a DC device. D'oh. Any suggestions?

Hi,

I recently bought a Linksys WRT54G v.1.0 from someone on ebay 'as-is'. The
price was right and I was in the mood for a little project. It came with the
old 5v2a power supply and when plugged in, only the 'power' and 'diag'
lights came on. They were blinking. The unit didn't respond to pings.

Figuring it was bricked from a firmware upgrade gone bad, I soldered in a
JTAG header and tried to fix it with the HairyDairyMaid debricker utility. I
backed up CFE and NVRAM, then erased both, then flashed it. Whilst flashing,
both the 'power' and 'diag' lights stopped blinking and stayed lit. But at
about 5% of the way through the CFE flash, it froze. After monkeying with
it, I found that by cycling power to the router when it froze, the flashing
process would continue. I ended up using this method to flash everything,
including the KERNEL, to the point where the HairyDairyMaid software
reported success in all cases. However, upon disconnecting from JTAG and
cycling power again, it was the same old story: blinking 'power' and 'diag'
lights and no ping response.

About this time, I noticed that something was loose in the power supply. It
rattled around inside when shaken. So I tested the power supply w/ a
multimeter which reported that it still did put out 5v.

Some research indicated that these units can handle more voltage than what
they're rated for. I noticed that the power adapter for my DSL modem was
12v. It fit into the receptacle on the WRT54G, so I plugged it in and was
greeted with a POP sound. I unplugged it immediately. There was a burnt
circuitry smell, but no smoke and no visible damage to the PCB or any chips
- even under magnification.

Well, upon closer inspection of the power adapter, I noticed it's output is
12v AC, and the router needs DC. Of course the router doesn't respond to any
power supply now and the lights no longer come on at all. Clearly a
boneheaded move on my part, but what's done is done.

My question: don't most electronic devices like this have some sort of fuse
protection on the board, to protect the circuitry from boneheads like
myself? Does anyone know if there's a varistor or something on the board
that I could just replace to bring it back from the dead?

Thanks,
Slade


slade969

slade969 <(E-Mail Removed)> hath wroth:

>Some research indicated that these units can handle more voltage than what
>they're rated for. I noticed that the power adapter for my DSL modem was
>12v. It fit into the receptacle on the WRT54G, so I plugged it in and was
>greeted with a POP sound. I unplugged it immediately. There was a burnt
>circuitry smell, but no smoke and no visible damage to the PCB or any chips
>- even under magnification.

Argh. If you had read carefully, you would have noticed that the
WRT54G v1.0 and v1.1 hardware versions are 5VDC only. The others will
run on anything between 4.5VDC and 18VDC. It's dead.

>Well, upon closer inspection of the power adapter, I noticed it's output is
>12v AC, and the router needs DC.

Maybe you're lucky. There's a protection diode on the v1.0 and v1.1
versions. See:
<http://www.linksysinfo.org/images/Content/Autopsy/WRT54G-mblg.jpg>
It's the black rectangular chip with the polarity stripe, to the right
of the SOT regulator package near the power connector. It's probably
shorted which may have protected the rest of the circuitry from your
destructive tendencies. Look for a bulge or dimple on top of the
diode, which usually indicates it has exploded inside.

>Of course the router doesn't respond to any
>power supply now and the lights no longer come on at all. Clearly a
>boneheaded move on my part, but what's done is done.

Welcome to Learn By Destroying(tm). My theory is that you don't
really undestand how something works until after you've trashed and
repaired it. Have your soldering iron warmed up and ready for action.
Incidentally, you're not the first one to have done the overvoltage
smoke test. I think your #3 that I know about. Nobody realized that
the v1.0 and v1.1 versions were different until fairly recently. Just
to make life really interesting, there are apparently two radically
different board layouts for the v1.1. One resembles the v1.0 while
the other has a wide range regulator similar to the v2.0 and above.

>My question: don't most electronic devices like this have some sort of fuse
>protection on the board, to protect the circuitry from boneheads like
>myself? Does anyone know if there's a varistor or something on the board
>that I could just replace to bring it back from the dead?

The diode is the most common culprit. There are some other hard to
find chips nearby that might also be fried. If that's the case, rip
out the diode, regulator, FET's and most everything related to the
voltage regulator, and replace it with a more modernish 3.3VDC
regulator. That's what the internal chipset runs on.

If you want to try your hand at surface mount repair, I think I can
supply the numbers for all the chips in the regulator section. I
think the 8 pin SOT regulator is an RT9202. The associated FET's are
9965 or 9985. I have not been able to find sources for any of these.




--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Wed, 23 May 2007 18:58:17 GMT, slade969 <(E-Mail Removed)>
wrote:

>Hi,
>
>I recently bought a Linksys WRT54G v.1.0 from someone on ebay 'as-is'. The
>price was right and I was in the mood for a little project. It came with the
>old 5v2a power supply and when plugged in, only the 'power' and 'diag'
>lights came on. They were blinking. The unit didn't respond to pings.
>
<snip>
OK now is a good time to add some info... I also have a WRT54G v.1.0
that I got not working. THe OEM wall-wort was the problem.
Here is the schematic of its output ckt...

+---+----|>|----+-----+-----L1-----+----+------->+5V
| | | | | |
( +--10R--1n--+ 330uF 220uF +-1K-+--(1)KA431 Vref=2.5V
( 25V 10V |
( 105° 105° 1K
| | | |
+---------------------+------------+---------+--(2)KA431

The 330uF, 25V input cap is adjacent to the rectifier diode & had
overheated. It had a "rounded top".

The wall wort would put out 5V unloaded but dropped to almost nothing
with any load.

Unit worked just fine with a good +5V wall wort.
(also flashed to dd-wrt)

>
>About this time, I noticed that something was loose in the power supply. It
>rattled around inside when shaken. So I tested the power supply w/ a
>multimeter which reported that it still did put out 5v.
>
>Some research indicated that these units can handle more voltage than what
>they're rated for. I noticed that the power adapter for my DSL modem was
>12v. It fit into the receptacle on the WRT54G, so I plugged it in and was
>greeted with a POP sound. I unplugged it immediately. There was a burnt
>circuitry smell, but no smoke and no visible damage to the PCB or any chips
>- even under magnification.

Here is a partial schematic I had made (ascii art)

+------>7705 chip
|
Jack1(+)--L2---F1---+-----+-----+-----+-----|>|--->SMPS
(-) | | | | 0.188V
| +-----+ | | |
| 1000uF| _|_ --- --- ---
L1 16V --- /_\ --- --- ---
| 105° --- | | | |
_|_ _|_ _|_ _|_ _|_ _|_
- - - - - -
ID= DS1 CK1 CA3 C3 D1

Device Zss smt smt smt Zss
ID 33 chip chip chip 33

"F1" is the yellow thing directly behind the pwr input jack.
using the pic Jeff posted...
<http://www.linksysinfo.org/images/Content/Autopsy/WRT54G-mblg.jpg>

"DS1" is mostly hidden in that pic - you can see part of it between F1 &
L1, the inductor closest to the pcb edge.

>Well, upon closer inspection of the power adapter, I noticed it's output is
>12v AC, and the router needs DC. Of course the router doesn't respond to any
>power supply now and the lights no longer come on at all. Clearly a
>boneheaded move on my part, but what's done is done.
>
>My question: don't most electronic devices like this have some sort of fuse
>protection on the board, to protect the circuitry from boneheads like
>myself? Does anyone know if there's a varistor or something on the board
>that I could just replace to bring it back from the dead?
>

The markings on "F1" are...
30V
JF34

Its not easily replaceable (soldered in).

Find a friend that knows some electronics & he/she should be able to
find the problem & maybe repair it.

Now for some more info on powering this unit. I had traced out the
input +5V lead & found that it also goes to some pins of the "radio
card". BUT I could not detect any connection to these pins (on the radio
card).

What I did discover is that the +5V also goes to a TI 7705AC chip at the
front edge of the main pcb & under the radio card. Its a "Supply Voltage
Supervisor" chip monitoring the health of the +5V line.

The 7705 chip pdf shows...
Vcc: 3.5-18 V
Vsense: Recommended Max= 10V

So it seems the resistors in the "Supply Voltage Supervisor" ckt would
be the limiting factor in higher voltage (DC) input to unit.

I have run this unit on a 6.5V wall-wort for a few days with no
problems.

kc - learned everything I know about wireless from this NG - thanks guys
& girls!

PS - Don't try to run a D-Link DI-524 above 5V. I was testing the
voltage/current curves & at 6.5V the PA amp shorted. I was able to
remove it & bridge the _tiny_ gap (what a pita!!) & the unit still works
fine, but _somewhat_ reduced power

Kim Clay <(E-Mail Removed)> hath wroth:

>Here is a partial schematic I had made (ascii art)
>
> +------>7705 chip
> |
>Jack1(+)--L2---F1---+-----+-----+-----+-----|>|--->SMPS
> (-) | | | | 0.188V
> | +-----+ | | |
> | 1000uF| _|_ --- --- ---
> L1 16V --- /_\ --- --- ---
> | 105° --- | | | |
> _|_ _|_ _|_ _|_ _|_ _|_
> - - - - - -
>ID= DS1 CK1 CA3 C3 D1
>
>Device Zss smt smt smt Zss
> ID 33 chip chip chip 33
>
>"F1" is the yellow thing directly behind the pwr input jack.
>using the pic Jeff posted...
><http://www.linksysinfo.org/images/Content/Autopsy/WRT54G-mblg.jpg>

I took a better photo. See:
<http://802.11junk.com/jeffl/pics/wireless/WRT54G/slides/wrt54g-v1.1.html>
This is my WRT54G v1.1 which might be quite different from your V1.0
version. If yours has the 5 terminal voltage regulator (near bottom
center of photo) marked Anachip AC1501-33:
<http://www.anachip.com/downloads/datasheets/power/sw_reg/AP1501.pdf>
then you have the version that can handle a wide range of input
voltages. If you have a tiny chip, as in the above Linksysinfo photo,
you have the 5V only version.

Note that the diode has been replaced with a 1N4001. F1 is suppose to
be a fuse of sorts, but is really a varistor, which has low resistance
when cold, but increases resistance radically when hot. It's doesn't
blow up like a fuse and recovers when it cools down.

>The 7705 chip pdf shows...
>Vcc: 3.5-18 V
>Vsense: Recommended Max= 10V

The what chip? I haven't seen that number in any WRT54G boards that
I've played with. It appears that there are a variety of power supply
designs, some of which are not distinguished by different hardware
version numbers. Oh-oh.

>So it seems the resistors in the "Supply Voltage Supervisor" ckt would
>be the limiting factor in higher voltage (DC) input to unit.

Yep.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Wed, 23 May 2007 20:45:42 -0700, Jeff Liebermann
<(E-Mail Removed)> wrote:

>Kim Clay <(E-Mail Removed)> hath wroth:
>
>>Here is a partial schematic I had made (ascii art)
>>
>> +------>7705 chip
>> |
>>Jack1(+)--L2---F1---+-----+-----+-----+-----|>|--->SMPS
>> (-) | | | | 0.188V
>> | +-----+ | | |
>> | 1000uF| _|_ --- --- ---
>> L1 16V --- /_\ --- --- ---
>> | 105° --- | | | |
>> _|_ _|_ _|_ _|_ _|_ _|_
>> - - - - - -
>>ID= DS1 CK1 CA3 C3 D1
>>
>>Device Zss smt smt smt Zss
>> ID 33 chip chip chip 33
>>
>>"F1" is the yellow thing directly behind the pwr input jack.
>>using the pic Jeff posted...
>><http://www.linksysinfo.org/images/Content/Autopsy/WRT54G-mblg.jpg>
>
>I took a better photo. See:
><http://802.11junk.com/jeffl/pics/wireless/WRT54G/slides/wrt54g-v1.1.html>
>This is my WRT54G v1.1 which might be quite different from your V1.0
>version. If yours has the 5 terminal voltage regulator (near bottom
>center of photo) marked Anachip AC1501-33:
><http://www.anachip.com/downloads/datasheets/power/sw_reg/AP1501.pdf>
>then you have the version that can handle a wide range of input
>voltages. If you have a tiny chip, as in the above Linksysinfo photo,
>you have the 5V only version.

I have the 8 pin SOT regulator - RT9202
My pcb looks identical to the pic at
<http://www.linksysinfo.org/images/Content/Autopsy/WRT54G-mblg.jpg>

>
>Note that the diode has been replaced with a 1N4001. F1 is suppose to
>be a fuse of sorts, but is really a varistor, which has low resistance
>when cold, but increases resistance radically when hot. It's doesn't
>blow up like a fuse and recovers when it cools down.

Fi seems to be a PolySwitch of some type.
<http://catalog.tycoelectronics.com/TE/bin/TE.Menu?M=MENU&ID=12653&BML=10576,16366&LG=1&I=13>
but I could not xref the number I found on the device

The markings on "F1" are...
30V
JF34

>
>>The 7705 chip pdf shows...
>>Vcc: 3.5-18 V
>>Vsense: Recommended Max= 10V
>
>The what chip? I haven't seen that number in any WRT54G boards that
>I've played with. It appears that there are a variety of power supply
>designs, some of which are not distinguished by different hardware
>version numbers. Oh-oh.

TI TL7705 - 5V "Supply Voltage Supervisor"
The +5V from the pwr jk runs directly to pins 7 & 8 of this chip.

This chip is really out of place as it is under the front edge of the
radio board, way away from the PS section.

Looking at the V1.0 pcb at
<http://www.linksysinfo.org/images/Content/Autopsy/WRT54G-mblg.jpg>
the chip would be on the main pcb under the far (front) edge of the
radio board, centered about 1cm from the front edge of the pcb - its a
"Supply Voltage Supervisor" 8-pin SOT.
This pic matches my pcb in every way.

afaik its the only device that uses direct +5V power besides the smps.

>
>>So it seems the resistors in the "Supply Voltage Supervisor" ckt would
>>be the limiting factor in higher voltage (DC) input to unit.
>
>Yep.

Kim Clay <(E-Mail Removed)> hath wroth:

>I have the 8 pin SOT regulator - RT9202
>My pcb looks identical to the pic at
><http://www.linksysinfo.org/images/Content/Autopsy/WRT54G-mblg.jpg>

That's the 5V only incantation. Don't try it with higher voltages.
<http://www.alldatasheet.co.kr/datasheet-pdf/pdf_kor/ETC/RT9202.html>
Note that it uses external FET's to increase the output power. Those
are what usually blow up.

>Fi seems to be a PolySwitch of some type.
><http://catalog.tycoelectronics.com/TE/bin/TE.Menu?M=MENU&ID=12653&BML=10576,16366&LG=1&I=13>
>but I could not xref the number I found on the device
>
>The markings on "F1" are...
>30V
>JF34

Yeah, that looks like the part. However, I gave up trying to find the
specs based on the "JF34" markings. It kinda looks like a LittelFuse
part number, but I'm too lazy to dig any more.

>>>The 7705 chip pdf shows...
>>>Vcc: 3.5-18 V
>>>Vsense: Recommended Max= 10V
>>
>>The what chip? I haven't seen that number in any WRT54G boards that
>>I've played with. It appears that there are a variety of power supply
>>designs, some of which are not distinguished by different hardware
>>version numbers. Oh-oh.
>
>TI TL7705 - 5V "Supply Voltage Supervisor"
>The +5V from the pwr jk runs directly to pins 7 & 8 of this chip.

<http://focus.ti.com/lit/an/slvae04/slvae04.pdf>
That's a chip that's used to insure that the CPU receives a hard reset
when the power supply gets cycled. It's not really part of the power
supply system. What I find odd is that it's running on 5V VCC instead
of the expected 3.3VDC. That means my suggestion of ripping out the
regulator section and running the WRT54G on 3.3VDC isn't going to
work. Argh.

>afaik its the only device that uses direct +5V power besides the smps.

Bummer.

Can you post or send me the FCC ID number for your WRT54G v1.0 unit?
I might get lucky and find a block diagram on the FCC ID web pile. If
you want to dig for yourself, go unto:
<https://gullfoss2.fcc.gov/oetcf/eas/reports/GenericSearch.cfm>
and inscribe
Grantee Code: Q87
Product Code: -WRT54G
Show: 100 records at a time.
Note the dash. It's required.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

<snip>
>Can you post or send me the FCC ID number for your WRT54G v1.0 unit?
>I might get lucky and find a block diagram on the FCC ID web pile. If
>you want to dig for yourself, go unto:
><https://gullfoss2.fcc.gov/oetcf/eas/reports/GenericSearch.cfm>
>and inscribe
> Grantee Code: Q87
> Product Code: -WRT54G
> Show: 100 records at a time.
>Note the dash. It's required.

FCC ID PKW-WM54G

1 Applications Were Found That Match the Search Criteria:
Grantee Code: PKW Product Code: -WM54G

<https://gullfoss2.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout =500&calledFromFrame=N&application_id=586522&fcc_i d='PKW-WM54G'>

I dunno if the link will work but the FCC "GenericSearch" found it!

Kim Clay <(E-Mail Removed)> hath wroth:

><snip>
>>Can you post or send me the FCC ID number for your WRT54G v1.0 unit?
>>I might get lucky and find a block diagram on the FCC ID web pile. If
>>you want to dig for yourself, go unto:
>><https://gullfoss2.fcc.gov/oetcf/eas/reports/GenericSearch.cfm>
>>and inscribe
>> Grantee Code: Q87
>> Product Code: -WRT54G
>> Show: 100 records at a time.
>>Note the dash. It's required.
>
>FCC ID PKW-WM54G
>
>1 Applications Were Found That Match the Search Criteria:
>Grantee Code: PKW Product Code: -WM54G
>
><https://gullfoss2.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout =500&calledFromFrame=N&application_id=586522&fcc_i d='PKW-WM54G'>
>
>I dunno if the link will work but the FCC "GenericSearch" found it!

That's not a WRT54G. It's the WM54G MiniPCI card used inside the
WRT54G v1.0 router. Just look at the internal and external photos.

Are you sure that's the number on the router serial number tag? This
is getting really weird.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Wed, 23 May 2007 22:42:28 -0700, Jeff Liebermann
<(E-Mail Removed)> wrote:

>Kim Clay <(E-Mail Removed)> hath wroth:
>
>><snip>
>>>Can you post or send me the FCC ID number for your WRT54G v1.0 unit?
>>>I might get lucky and find a block diagram on the FCC ID web pile. If
>>>you want to dig for yourself, go unto:
>>><https://gullfoss2.fcc.gov/oetcf/eas/reports/GenericSearch.cfm>
>>>and inscribe
>>> Grantee Code: Q87
>>> Product Code: -WRT54G
>>> Show: 100 records at a time.
>>>Note the dash. It's required.
>>
>>FCC ID PKW-WM54G
>>
>>1 Applications Were Found That Match the Search Criteria:
>>Grantee Code: PKW Product Code: -WM54G
>>
>><https://gullfoss2.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout =500&calledFromFrame=N&application_id=586522&fcc_i d='PKW-WM54G'>
>>
>>I dunno if the link will work but the FCC "GenericSearch" found it!
>
>That's not a WRT54G. It's the WM54G MiniPCI card used inside the
>WRT54G v1.0 router. Just look at the internal and external photos.
>
>Are you sure that's the number on the router serial number tag? This
>is getting really weird.

The bottom of the router has 2 stickers -
one has the s/n & the mac address & no FCCID #.

another sticker has:
FCC ID PKW-WM54G
IC ID: 3839A-WM54G

On Wed, 23 May 2007 22:42:28 -0700, Jeff Liebermann
<(E-Mail Removed)> wrote:

>Kim Clay <(E-Mail Removed)> hath wroth:
>
>><snip>
>>>Can you post or send me the FCC ID number for your WRT54G v1.0 unit?
>>>I might get lucky and find a block diagram on the FCC ID web pile. If
>>>you want to dig for yourself, go unto:
>>><https://gullfoss2.fcc.gov/oetcf/eas/reports/GenericSearch.cfm>
>>>and inscribe
>>> Grantee Code: Q87
>>> Product Code: -WRT54G
>>> Show: 100 records at a time.
>>>Note the dash. It's required.
>>
>>FCC ID PKW-WM54G
>>
>>1 Applications Were Found That Match the Search Criteria:
>>Grantee Code: PKW Product Code: -WM54G
>>
>><https://gullfoss2.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout =500&calledFromFrame=N&application_id=586522&fcc_i d='PKW-WM54G'>
>>
>>I dunno if the link will work but the FCC "GenericSearch" found it!
>
>That's not a WRT54G. It's the WM54G MiniPCI card used inside the
>WRT54G v1.0 router. Just look at the internal and external photos.
>
>Are you sure that's the number on the router serial number tag? This
>is getting really weird.

Actually the external sticker on the bottom of my unit that has the
FCCID # is the same sticker that in on the RF shield in this pic
<http://www.linksysinfo.org/images/Content/Autopsy/WRT54G-mblg.jpg>

My unit has identical stickers on the bottom of its case & on the RF
shield internally.