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

Kim Clay <kimclay@xxxxxxxxxxxxx> 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 jeffl@xxxxxxxxxxxxxxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.