How to convert 4 pin audio (CD_IN) to 3.5mm connector?

[PremiumG]

I have a TV tuner card that has a 4 pin audio output (same as CD-ROM drives).

My motherboard's built in sound card does not have a 4 pin audio header. Is it possible to connect the 4 pin out from the TV tuner card to the 3.5mm line in on the back of the computer?

I've cut open a 3.5mm headphone line and I only see two wires. The 4 pin requires left, right, and ground. I don't see a 'ground' wire when cutting a headphone's line.

 

[Mday]

I have a TV tuner card that has a 4 pin audio output (same as CD-ROM drives).

My motherboard's built in sound card does not have a 4 pin audio header. Is it possible to connect the 4 pin out from the TV tuner card to the 3.5mm line in on the back of the computer?

I've cut open a 3.5mm headphone line and I only see two wires. The 4 pin requires left, right, and ground. I don't see a 'ground' wire when cutting a headphone's line.

Are you sure your sound card doesnt have a pc99 audio socket or something?

When you cut: did you see any uninsultated wires at all Or do you just see 2 insulated wires?

There are typically 2 kinds of headphone cables, one that is a singular "cable" going into the plug, and another that is a pair of "cables" going into the plug (usually seen in cheap ear plugs). The former if you cut through it, should have 2 insulated wires, and another wire which may or may not be insulated or is worked into some sort of shield. The latter basically has each of the cables branching off continuously into each ear piece, and if you cut either one, you get an insulated wire, and a bare wire (usually).

 

[PremiumG]

I actually saw 2 pairs of uninsulated wires. A pair for each headphone side.

Each pair was twisted so there's no way either cable can be ground if they're twisted.

 

[William Gaatjes]

I actually saw 2 pairs of uninsulated wires. A pair for each headphone side.

Each pair was twisted so there's no way either cable can be ground if they're twisted.

Good day...

If i understand correctly, you have 2 pairs of wires where each pair is 2 wires twisted. I may be wrong but it is very likely that at least 1 of those wires from a single pair, has a coating on it. It will reflect light differently.
it is probably an enameled wire. This means the 2 wires are electrically isolated form each other.

http://en.wikipedia.org/wiki/Enameled_wire

Enameled wire
From Wikipedia, the free encyclopedia

Enameled wire is wire (such as magnet wire) coated with a very thin insulating layer. It is used in applications such as winding electric motor coils, speakers and transformers. It is also used in the construction of electromagnets and inductors.

The core material is copper or aluminum, coated with a thin layer of a polyurethane, polyamide, or polyester etc resin - the so-called "enamel". Aluminum is lighter than copper, but has higher resistivity.

For ease of manufacturing inductive components like transformers and inductors, most new enameled wire has enamel that acts as a flux when burnt during soldering. This means that the electrical connections at the ends can be made without stripping off the insulation first. Older enameled copper wire is normally not like this, and requires sandpapering or scraping to remove the insulation before soldering.

Enameled wires are classified by their diameter (AWG number or SWG) or area (square millimetres), temperature class and isolation class. Enameled wires are manufactured in both round and rectangular shapes. Rectangular wire is used in larger windings to make the most efficient use of available winding space.

Breakdown voltage depends on the thickness of the covering, which can be of 3 types: Grade 1, Grade 2 and Grade 3. Higher grades have thicker insulation and thus higher breakdown voltages.

The temperature class indicates the temperature of the wire where it has a 20,000 hour service life. At lower temperatures the service life of the wire is longer (about a factor 2 for every 10 °C lower temperature). Common temperature classes are 120, 155 and 180 °C.

 

[Paperdoc]

The line to the earphones may have two pairs, each of two wires twisted together. But for sure in each pair, one is signal + and one is signal -. Signal - is also known as Ground because that's the way the amplifier outputs and inputs are wired. So although they appear separate, in fact one of the wires in each twisted pair IS a Ground. Now, you have a 4-pin output on the TV Tuner card, and I assume you have the exact pin assignments for that. Often they actually provide separate Ground pins for each channel, but they really are the same Ground so you can safely join the two Ground leads together when you solder on a 3.5 mm Stereo connector at the other end. (Your easiest plan may be to get a common 4-wire cable with connectors intended for use between an older CD player and a sound card, and then replace one end with a 3.5 mm Stereo plug.) The remaining challenge is to match Left and Right lines to the correct points in the 3.5 mm plug. For that, check out this Wiki item:
http://en.wikipedia.org/wiki/TRS_connector

You'll see a bit more than half way down the page that the outermost "Sleeve" is the common Ground, the middle "Ring" is Right channel signal +, and the "Tip" is Left channel signal +. For a memory aid, try this: Tip (shortest word) is Left (shortest); Ring (medium length) is Right (medium); Sleeve (longest word) is Ground (longest).