Hi all.

The Power-Over-Ethernet (POE) injector for a ZyXEL wireless network
link has just failed. New, or replacement, POEs are not easy to locate
nor is information on these devices. There is not any label or other
markings indicating model numbers or other information.
I opened the POE unit and discovered that it contains an AP34063
switching regulator, as would be expected, but also an LM358D (dual
OpAmp).
Does anyone have any idea why a POE unit would contain an OpAmp?

Regards.

Mike

Am 13.07.2010 15:03, schrieb AC Me:
Hi all.

The Power-Over-Ethernet (POE) injector for a ZyXEL wireless network
link has just failed. New, or replacement, POEs are not easy to locate
nor is information on these devices. There is not any label or other
markings indicating model numbers or other information.
I opened the POE unit and discovered that it contains an AP34063
switching regulator, as would be expected, but also an LM358D (dual
OpAmp).
Does anyone have any idea why a POE unit would contain an OpAmp?

To prevent injecting 40somewhat volts into an ISDN link or something
else not aware of PoE?
Reverse engineer the circuit, and you will not only see how it's done
but also be able to repair this thing. Interesting enough that it uses a
34064, I also use lots of them

On Jul 13, 5:59*pm, Stefan Huebner ste...@huebner-
informationselektronik.de wrote:
Am 13.07.2010 15:03, schrieb AC Me:

Hi all.

The Power-Over-Ethernet (POE) injector for a ZyXEL wireless network
link has just failed. New, or replacement, POEs are not easy to locate
nor is information on these devices. There is not any label or other
markings indicating model numbers or other information.
I opened the POE unit and discovered that it contains an AP34063
switching regulator, as would be expected, but also an LM358D (dual
OpAmp).
Does anyone have any idea why a POE unit would contain an OpAmp?

To prevent injecting 40somewhat volts into an ISDN link or something
else not aware of PoE?
Reverse engineer the circuit, and you will not only see how it's done
but also be able to repair this thing. Interesting enough that it uses a
34064, I also use lots of them

Thank you Stefan. That is interesting.
I have examined the unit more closely with a view to reverse
engineering it.
There seem to be a lot of components on the board and the board seems
to have more that two layers (there are few track on the top and fewer
still
on the bottom both of which are mostly copper). This looks daunting -
but
let's proceed.
First steps: How many components and what type?
I hope I haven't missed anything.
There are 2 x RJ45 through-hole sockets, 1 x DC power jack through-
hole,
2 x Electrolytics through-hole and 1 x through-hole inductor.
The surface-mount contingent consists of 4 x Zener, 2 x LED, 1 x NPN
SOT-23,
1 x NPN TO-252, 1 x Inductor, 1 x Diode, 18 x Resistor, 5 x Capacitor,
1 x
Transient Voltage Suppressor and 1 x Fuse.
..
That last component is tucked up neatly beside the 'output' (if I may
describe
it as such) RJ45 connector and is almost completely transparent. It
would
appear to be a Littlefuse 375mA device (marking of FE).
It would also appear to be blown.
And so this blown fuse might well be the problem. Now to track down a
replacement.

Thank you Stefan for your help.
By the way, are there any 'design guides', 'thoughts for a long
Winter's evening',
etc, on POEs available that would help explain these types of devices
to
an idiot like me?
I'm sure they would make interesting reading the next time I am bored.


Take care.

Mike

On Jul 14, 12:42*pm, AC Me wrote:
On Jul 13, 5:59*pm, Stefan Huebner ste...@huebner-



informationselektronik.de wrote:
Am 13.07.2010 15:03, schrieb AC Me:

Hi all.

The Power-Over-Ethernet (POE) injector for a ZyXEL wireless network
link has just failed. New, or replacement, POEs are not easy to locate
nor is information on these devices. There is not any label or other
markings indicating model numbers or other information.
I opened the POE unit and discovered that it contains an AP34063
switching regulator, as would be expected, but also an LM358D (dual
OpAmp).
Does anyone have any idea why a POE unit would contain an OpAmp?

To prevent injecting 40somewhat volts into an ISDN link or something
else not aware of PoE?
Reverse engineer the circuit, and you will not only see how it's done
but also be able to repair this thing. Interesting enough that it uses a
34064, I also use lots of them

Thank you Stefan. That is interesting.
I have examined the unit more closely with a view to reverse
engineering it.
There seem to be a lot of components on the board and the board seems
to have more that two layers (there are few track on the top and fewer
still
on the bottom both of which are mostly copper). This looks daunting -
but
let's proceed.
First steps: How many components and what type?
I hope I haven't missed anything.
There are 2 x RJ45 through-hole sockets, 1 x DC power jack through-
hole,
2 x Electrolytics through-hole and 1 x through-hole inductor.
The surface-mount contingent consists of 4 x Zener, 2 x LED, 1 x NPN
SOT-23,
1 x NPN TO-252, 1 x Inductor, 1 x Diode, 18 x Resistor, 5 x Capacitor,
1 x
Transient Voltage Suppressor and 1 x Fuse.
.
That last component is tucked up neatly beside the 'output' (if I may
describe
it as such) RJ45 connector and is almost completely transparent. It
would
appear to be a Littlefuse 375mA device (marking of FE).
It would also appear to be blown.
And so this blown fuse might well be the problem. Now to track down a
replacement.

Thank you Stefan for your help.
By the way, are there any 'design guides', 'thoughts for a long
Winter's evening',
etc, on POEs available that would help explain these types of devices
to
an idiot like me?
I'm sure they would make interesting reading the next time I am bored.

Take care.

Mike

Actually, when I write POE I really mean POE Injector.

Sorry if this has caused any confusion.

Mike