Raspberry Pi 3 Model B v1.2 - Connect to old TV via Composite Video Output

Question

I have a Raspberry Pi 3 Model B v1.2. It works great on my TV that has HDMI port, but I am trying to hook it up to a TV that only has A/V and Composite Video inputs. From what I understand, I needed to buy a 3.5mm to A/V cable so I could plug into the 3.5mm 4-pole Composite Video and Audio Output as seen in the below image.

I've done this, and I can not figure out how to make it work on this older TV. It doesn't seem to do anything when plugged into this port. Do I need to make changes to the config.txt file to force output to this Composite Video port or is there something else I am missing?

This is the cable that I bought to connect it. https://www.amazon.com/gp/product/B00CIC9KW2/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Answer 1

According to Adafruit product information for a similar product, the plug is TRRS, which stands for Tip, Ring, Ring, Sleeve. I wasn't able to locate specific information for your Amazon product, but it is common for such connectors to have the Sleeve for ground. The Adafruit listing specifies respectively, Left, Right, Ground, Video.

This is important, as the ground conductor is often used for shielding. If you have a typical/standard/conventional connector and wiring, your video lead is now the shielded conductor and there may be complications respective to your grounding.

You can perform some tests if you have a multimeter or even a battery and an LED or light bulb. Connect one lead to the sleeve of the plug and touch the outer ring of any of the three RCA connectors. The light should light or the meter should show conductivity. If that happens, you have an incompatible cable, which I believe will be the case.