5. Safe Operation & Troubleshooting

Updated: 2026-06*

This final chapter summarizes the rules for safe operation and how to respond when trouble happens.

In particular, “forgetting to turn the lights off” is the most common accident with this kind of system. If you understand the mechanism, you can prevent it.

Why people forget to turn the lights off

In Chapter 4 we wrote “always turn off the lights before closing QLC+.” This isn’t just etiquette — it’s a constraint that comes from the DMX standard itself.

DMX’s “Hold Last Look” behavior

In the DMX standard, when the signal stops, the standard behavior is for a fixture to keep holding the last value it received. This is called Hold Last Look.

[Set to 80% brightness in QLC+]
        ↓
[Close QLC+]
        ↓
[The Art-Net signal stops]
        ↓
[The ODE Mk2 keeps outputting the last signal]
        ↓
[The light stays on at 80%] ⚠️

In other words, closing the software does not turn the lights off. They stay on until the next person comes, or until the power is cut.

The solution: explicitly “send 0%”

To avoid this, before closing QLC+, set every fader to 0 — that is, send a “0% brightness” DMX command — and only then quit the software.

That way the value held by Hold Last Look is also 0, so the lights stay off.

This is why Chapter 4’s rule, “always blackout before quitting,” is necessary.

Operating rules for users

Things you must do

Things you must not do

• ❌ Plug or unplug DMX or LAN cables
• ❌ Touch the switches or settings on the ceiling fixtures themselves
• ❌ Change QLC+’s fixture settings
• ❌ Access the ODE Mk2’s web interface and change its settings
• ❌ Choose “Save / Yes” and overwrite the configuration file

End-of-use checklist

Before leaving your seat, always confirm the following.

□ Dragged all faders down in the Virtual Console,
  or pressed the blackout button

□ Visually confirmed all 7 ceiling fixtures are completely off
   ・Diva-Lite 31  ×4
   ・ARRI L7-C Plus ×3

□ Quit QLC+ via File → Quit

□ Chose "No" when asked "Save?"

□ Put the PC to sleep or shut it down

Just keeping to this checklist prevents almost all unattended-operation trouble.

Troubleshooting

Common problems during use and the steps to handle them. Don’t change settings yourself — limit yourself to isolating the symptom.

Q1. None of the lights respond

The signal path is broken somewhere. Check in order, starting from the PC.

1. Is the PC’s Wi-Fi connection the lighting router?
   • No → switch to the correct SSID
2. Is QLC+ in Operate mode?
   • No → switch to Operate mode with the ▶ button at top-right
3. Is the ODE Mk2’s power LED lit?
   • Off → check the ODE Mk2’s power and LAN cable
   • Don’t plug/unplug yourself — contact the administrator
4. Is the router’s power on?
   • Off → contact the administrator

Q2. Only a specific light doesn’t respond

A broken DMX cable, or that light’s power being off, is suspected.

1. Visually confirm that light’s power is on
   • Is the unit’s standby LED, etc., lit?
2. Check whether the other lights work normally
   • Others work = a wiring or that-light problem
   • Others don’t work either = a problem with the whole chain

→ In either case, don’t touch the wiring yourself — contact the administrator

Q3. A different light responds than the one you operated

A DMX address mismatch may have occurred.

• Blackout to turn everything off for now
• Contact the administrator
• In many cases, reloading the configuration file is needed

Q4. QLC+ won’t launch / crashed

1. Restart the PC
2. Launch QLC+ again
3. Still no good → contact the administrator

If the lights were on before the crash, they’re stuck on due to Hold Last Look. Relaunch QLC+ once, blackout, and then quit.

Q5. The light’s color is off (green cast, purple cast, etc.)

The HSI/RGB mode settings may be in a half-finished state.

1. Blackout to reset for now
2. Reopen the project file
3. If it doesn’t improve, contact the administrator

Q6. After the shoot, you turned the lights off but ceiling lights are still on

Just pressing the blackout button can leave certain faders raised.

1. Visually check every fader in the Virtual Console — are they all all the way down?
2. Still won’t go off → that light’s DMX address may be mismatched
3. Contact the administrator

Contacting the administrator

In the following cases, don’t try to solve it yourself — contact the administrator immediately.

• The lights won’t go off
• Wiring is unplugged / broken
• QLC+’s settings have changed
• The ODE Mk2 or router is in a strange state
• Physical damage, smoke, or a burning smell

Contact

Administrator: ___________________
Phone/email: ___________________
Outside hours: ___________________

(The actual contact details are to be filled in by the administrator.)

Safety notes

Electrical safety

• Users never need to touch the ceiling fixtures or wiring
• If a cable is on the floor or unplugged, don’t touch it — tell the administrator
• Don’t put water or drinks near the equipment

Care for your eyes

• LED fixtures put out strong light. Avoid staring at them for long periods.
• During shooting, the basic approach is to check through a monitor

Equipment temperature

• The ARRI L7-C Plus gets hot during use
• Don’t touch it right after use (the administrator may perform maintenance)

Summary: the three golden rules

It’s been a long series, but there are just three things to remember.

1. Check Wi-Fi before you start — connect to the lighting router, then open QLC+
2. Don’t touch the settings — work in Operate mode and never overwrite-save
3. Always turn off before closing — blackout → visual confirm → quit with “Don’t save”

Keep these three, and anyone can use the studio’s lighting system safely.

In closing

DMX and QLC+ can feel hard to grasp at first. But once you see the whole picture, “why a fader on the PC can move a ceiling light” clicks into place.

We hope this series becomes a gateway to creative lighting on set.

As you get used to the controls, do try out all sorts of lighting patterns. The three- and four-point lighting that professional photographers use, cinematic lighting, the bold colors of fashion shoots — all of it can be realized in this studio.

Please send questions, requests, and trouble reports to the administrator.