How can I make this TV lift control box smart?

Question

I have a TV bed with a lift in the footboard. The lift is operated by an IR remote to a soundbar (also in the footboard). There's a couple of niggles with how it operates, such as the soundbar needing to be powered on for around 12 seconds before the TV will lift up or down. I'm currently in a bit of a drive to make everything smart, I've got Home Assistant set up with a bunch of scenes and automations and I'm currently researching ESPHome and thought it might be a good first project to get into, but I'm a bit out of my depth even after researching similar devices with an up/down action (garage doors, recliner chairs).

I have an ESP8266 NodeMCU (v3) board and I've been able to program and connect to it using ESPHome and Home Assistant. I'm not sure of the next steps now, and need a bit of help.

Here's a diagram of the TV lift control mechanism:

A is a 4-pin molex connector with 3 wires in it. B is a 5-pin locking din connector with 4 pins in use. It appears 2 wires go to the lift and 2 wires come from the AC adaptor, whose output is 29V at 2A to 29V at 4A max.

Inside the control box, there are 2 20A relays, I assume (correct me if I'm wrong) one is to make the lift go up and the other is to make the lift go down. The following photo shows the circuit board components, the top cable goes to the soundbar for control and the bottom cable goes to the AC adaptor and lift mechanism.

Here's the rear of the board (not sure how helpful it is but I wanted to be thorough):

So, I think I have two options for my ESP8266 board:

1. replicate the behaviour of the 3 wires coming from the soundbar; or
2. control 2 identical relays to send power to the lift

I think 1 would be simpler, but I'm not entirely sure. How can I figure out what those wires do using a multimeter, then set up my ESP8266 to do the same? And how can I ensure the control box remains powered by my device when the soundbar is switched off?

Answer 1

Option 1 is probably the safest bet - relying on the existing board which has already been designed to do everything required to interface with hardware.

I would assume the two components at the top of the board as shown (4-pin DIP packages) are optocouplers. In which case interfacing the existing board with a different device (such as ESP) will be a case of figuring out what the signals. No extra hardware is likely required to interface the ESP, just hook up to two IO pins.

The three wires feeding in will be two control signals (white and black) and GND (green). I would try probing them with a multi-meter when the TV is moving up and down. If they are just on-off control signals a voltage meter should be sufficient to figure out what they do. If they are something more complex, you'd probably want a logic analyser.

In a simple world the signals would be just "Go-up" and "Go-down", but they could be something more complicated.