IP2 Connector

Do you have a question? Post it now! No Registration Necessary.  Now with pictures!

Threaded View
I just pulled a G31T-LM2 motherboard out of a Lenovo 3000 H series  
desktop computer.  The onboard USB and LAN and failed, and it made some  
sense to just grab another G31 motherboard now while I can find one cheap.

It's been a pretty smooth replacement in spite of non-standard front  
panel, USB and audio connectors.  One connector, or some curiosity, if  
not importance is an "IP2" connector.  It has 3 leads (in a 2x2  
configuration) that run to a 2n3904 transistor mounted at the bottom of  
the front panel, about where you would expect an IR receiver to be located.

It does not appear to be an IR receiver, however, and is covered by  
opaque plastic and a thin bit of aluminum on the front panel.

What is this thing?

Re: IP2 Connector

On 10/01/2013 07:14 PM, Grinder wrote:
Quoted text here. Click to load it

Is this it?


If so it's for spdif speakers (digital audio)

Re: IP2 Connector

On 10/1/2013 7:31 PM, philo  wrote:
Quoted text here. Click to load it

No.  It is a transistor on a 20cm cable that plugs into a 3-pin header  
(2x2 configuration with 0.1" seperation) on the motherboard.  Screened  
on the motherboard next to the connectors is "IP2"

Re: IP2 Connector

Grinder wrote:
Quoted text here. Click to load it

Any chance the opaque plastic passes infrared light and blocks visible light ?

Can you trace the cabling from there to the motherboard header ? Any
legend on the motherboard silk screen for the pins involved ?


If I go to ecs.com.tw and look at a motherboard from the G31T series,
it had a four pin S/PDIF connector. But since the web.archive.org
page doesn't work properly, I can't actually download the manual for it
and figure out where that connector is located. I don't even know
if this is the standard 1x4 linear connector, or some kind of 2x2

    Pin 1: S/PDIF_out
        2: +5V
        3: (missing - key location)
        4: Ground

How some of those work, is a "non-standard" signal comes from there,
to be followed by a resistive attenuator on the faceplate (or otherwise)
connector for it. S/PDIF is supposed to be transformer coupled and
around 1V or less in amplitude. Whereas some goofy motherboards
have a 3.3V amplitude square wave coming from the S/PDIF_out interface
of the audio CODEC. And then there's a matching network where the
coax cable gets connected.

If you have a nice looking square wave, you can feed that direct to
a $1.00 TOSLink red LED transmitter module. Again, that can be front
panel mounted. In the case of one laptop, the red LED light is
co-linear with the line_out connector, so you can either get analog
stereo from Tip-Ring-Sleeve, or by plugging an appropriate adapter,
run the red light down a TOSLink cable (for digital audio).

Since I can't find any decent pictures worth a damn of that
stuff, I can't really guess any more precisely than that. And you
don't expect an OEM motherboard manual from Lenovo (for the ECS
motherboard used). There were a few claims that's an ECS motherboard,
but how would I know from here ?


Re: IP2 Connector

On 10/1/2013 8:10 PM, Paul wrote:
Quoted text here. Click to load it

I'm pretty sure that's a thin layer of aluminum on top of plastic.  It's  
not that dark red transluscent stuff, but I don't know if opaque black  
plastic can pass IR.  There's not "port" like you typically see for an  
IR sensor.

Quoted text here. Click to load it


Any > legend on the motherboard silk screen for the pins involved ?


Re: IP2 Connector

On 10/1/2013 8:10 PM, Paul wrote:
Quoted text here. Click to load it

There's a part number on the cable: 45J9518

Warmer: This site lists it as "sensor cable"

Warmer still: This site lists it as Thrermo  [sic] Cable

Hot: eBay has it as temperature sensor:

Re: IP2 Connector

Grinder wrote:
Quoted text here. Click to load it

My first thought when looking at that info, was "why does it have
three wires and not two". Thermal sensors are done two ways.
You can use a NTC thermistor (two wires). Or you can use a diode (two wires).
A transistor can be used as a diode. And that should use two wires.
If the transistor was an NPN, perhaps they'd connect
base and collector together, and use collector to emitter as a sensor.

The only other thing I can think of, is it doesn't terminate in
the hardware monitor, and instead ties into a fan control of some
sort directly. In which case they could use all three legs of the

Pretty weird in any case.

When I wanted a "room temperature" sensor for my P4 based computer,
I used an NTC thermistor for that (back when Radio Shack sold just
the right one for the job). But some of the SuperI/O chips have lookup
tables, and can be set for "thermistor" or "diode" operation. So
if you don't have a thermistor handy, you can also experiment
with a diode.


Site Timeline