Film school puzzle in the Desiderium (blue RCA cable and Black Bulb)

Where the puzzle is

The Desiderium is the corrupted version of the building that you enter after meeting Sanguis on the film set. This puzzle is its version of the film school, built around three colored doors: red, blue and magenta.

The clue is the cable itself: Julia notes that these cables are usually yellow, but this one is blue. The Black Bulb inverts the colors of a room, which turns the blue cable into the yellow one the camera setup expects.

Not sure you’re in the right place? Search for your room in Quick find tool.

What you need

• RCA Cable (blue): the TV room behind the red door
• Black Bulb: on the desk behind the blue door
• Apartment Key: already in your inventory from the start of the game
• Red Candle: behind the blue door one floor down, at the end of this puzzle
• Lighter: from the film offices earlier in the game (it is in the inventory from the poster puzzle on; the exact pickup spot is not confirmed)

Exact spots for each one are on Items and collectibles.

Step by step

1. Red door: turn on the TVs and take the cable

   Go through the red door, switch the TVs on and pick up the RCA Cable. In this version of the building it is blue.

2. Blue door: take the Black Bulb

   Behind the blue door the Black Bulb sits on the desk. Take it.

3. Fit the Black Bulb in the red-door room one floor up

   Climb one floor and go through that floor's red door. Put the Black Bulb in the lamp there. The colors flip, and the cable now counts as yellow.

4. Magenta door: plug in the cable and climb it

   Go back down a floor to the magenta door, plug the cable in and climb up it.

   

5. Time the lever to get past the current

   An electric current blocks the way. Flip the lever, wait, flip it again, run through, then flip it once more behind you.

6. Blue door: break the glass and clear the goop

   At the next blue door, smash the glass and use the Apartment Key on the goop to get through.

7. Light the Red Candle on the stairwell symbol

   One floor down, behind the blue door, take the Red Candle. Light it with the Lighter and use it on the symbol next to the stairwell and elevator.

If it doesn’t work

The cable won't work behind the magenta door.

The Black Bulb has to be in the lamp behind the red door one floor up first. Until the colors are inverted the cable is still the wrong color.

The current keeps hitting me.

Don't run on the first flip. The pattern is flip, wait, flip, run, then flip again once you are past.

I can't get past the goop behind the blue door.

Smash the glass first, then use the Apartment Key, the key you have carried since the start of the game.

Sources

1. Tenebris Somnia - All Puzzles & Solutions Guide by iampanax Timestamps used: 34:21–39:23
2. Tenebris Somnia Full Game Walkthrough - All 4 Endings [No Commentary] by iampanax Timestamps used: 3:00:07