Manaras Light Curtain Guide — Specs, Wiring, and Maintenance

What a Manaras light curtain actually does

A Manaras light curtain replaces the single pair of photo-eyes at the bottom of a commercial door with a dense vertical grid of thru-beam sensors. The MLC-K36 covers 3 feet (0.91 m) of height; the MLC-K72 covers 6 feet (1.8 m). Both span up to 32 feet wide. When any beam in that grid is interrupted — a forklift tine, a pallet corner, a person’s leg — the curtain sends a monitored signal to the operator’s BOARD070M control board and the door reverses immediately. This is primary external entrapment protection per UL325, not an ancillary add-on.

Monitored versus non-monitored — why it matters

The monitored versions (MLC-K36 and MLC-K72) perform a continuous self-check. The transmitter and receiver exchange a coded signal every few milliseconds. If a lens gets dirty, a cable gets cut, a power supply drifts, or a sensor fails, the curtain reports a fault to the BOARD070M and the door will not close — it holds open or reverses, depending on how the operator is programmed. A non-monitored curtain cannot do that. If a beam goes dark on a non-monitored unit, the door sees clear path and closes. On a commercial door cycling 50 times a day, that difference is the difference between a near-miss and an injury claim.

Protection height — choosing K36 or K72

The K36 protects the bottom 36 inches of the opening. That covers most pedestrian traffic and the lower portion of a forklift load. The K72 protects 72 inches — the full height of a standard pallet on a Class II forklift, and the torso of an adult walking through. If your door serves loading docks where loads pass close to the jambs, or if pedestrian traffic mixes with vehicle traffic at the same opening, the K72 earns its keep. The mounting brackets and 3 feet of cable are included with either model. The K72 simply has twice the emitter/receiver pairs stacked vertically in the same IP67 housing.

Wiring to the BOARD070M — what the manual leaves out

The spec sheet says “simplified wiring” and “no external interface box required.” What it does not say is that the BOARD070M must be configured for monitored light curtain input — it does not auto-detect. On a new operator, that is a dip-switch or menu setting. On a retrofit, you are adding two conductors (signal and common) to the existing safety circuit, plus 24 VDC power to the curtain if the operator’s accessory supply cannot carry the load. The curtain draws roughly 150 mA per side at 24 VDC. Most Manaras commercial operators (OMH, OPH, OMJ, OPJ, OSH, OTH, OTBH, OMT) have enough accessory capacity, but verify the label before you parallel it with photo-eyes, edge sensors, and a loop detector on the same bus.

Run the curtain cable in its own conduit or at least separated from motor leads. The signal is low-voltage and susceptible to induced noise from the motor contactors. I have seen a curtain fault every time the brake solenoid fired because the installer zip-tied the curtain cable to the motor whip. Separate them.

Alignment — the part everyone rushes

Each curtain housing contains multiple emitter/receiver pairs. They are factory-aligned, but the mounting brackets have play. If you bolt the brackets to the track angle and walk away, you will get nuisance faults. The correct procedure:

1. Mount both housings loosely on their brackets.

2. Power the system. The receiver LED will indicate signal strength — usually green for good, amber for marginal, red for loss.

3. Adjust one housing at a time for maximum signal across the full width. Tighten.

4. Repeat for the other side.

5. Cycle the door 10 times. Watch the receiver LED on each cycle. It should stay solid green.

If the LED flickers amber on the downstroke, the door panel or strut is flexing into the beam path. Shim the bracket out 3 mm and retest. Do not widen the gap between housings beyond 32 feet — the spec limit is real. Beyond that, the beam spread exceeds the receiver aperture and you lose margin.

IP67 — what it survives and what it doesn’t

IP67 means the housing survives temporary immersion (1 meter, 30 minutes) and complete dust exclusion. It does not mean the lenses clean themselves. In a recycling facility or a grain terminal, dust builds up on the emitter and receiver faces until the signal drops below threshold. The monitored circuit will fault — which is what you want — but the door is now stuck open. Build lens cleaning into the monthly PM. A microfiber cloth and isopropyl alcohol. No pressure washers. The housing seals are rated for immersion, not a 3,000 psi wand at 6 inches.

Common failure modes

Cable damage at the hinge point. The 3-foot pigtail exits the housing and runs to the junction box. On a sectional door, that cable flexes every cycle. If the installer left no service loop, the conductors fatigue inside the jacket. The monitored circuit sees an open or short and faults. Fix: replace the pigtail (Manaras sells spares) and leave a 6-inch loop secured with a cable tie to the track angle.

Condensation inside the housing. Rare, but it happens in high-humidity cold storage. The IP67 seal holds water out, but temperature cycling pulls humid air in through the cable gland. When the door hits the freezer cycle, that air condenses on the lenses. The curtain faults at 4 AM. Fix: a desiccant pack inside the housing (non-conductive, taped to the PCB) and a proper cable gland with a drip loop.

BOARD070M firmware mismatch. Older BOARD070M revisions (pre-2019) do not support the monitored curtain handshake. The curtain powers up, the operator sees a fault, and the door will not close. Fix: update the board firmware via the Manaras USB tool, or swap the board. Check the board date code before you quote the job.

Maintenance that actually extends life

• Monthly: wipe lenses, verify LED status on a full cycle, inspect cable jacket at flex points.
• Quarterly: check bracket torque. Vibration loosens the 5/16-inch bracket bolts. A loose bracket shifts alignment 2 mm — enough to drop signal from green to amber.
• Annually: test the monitored fault response. Disconnect one curtain cable at the junction box. The door must refuse to close. Reconnect. Verify normal operation. This proves the monitoring circuit is alive, not just the beams.

When to replace instead of repair

If the housing is cracked from forklift impact, replace the unit. The IP67 seal is compromised and the internal PCB is likely stressed. If the receiver LED never reaches green after realignment and cable replacement, the emitter array has degraded — replace. If the BOARD070M logs repeated “curtain communication fault” codes and the wiring tests clean, the curtain’s internal transceiver has failed. These are not field-repairable.

Spec summary for submittals

Both include mounting brackets and 3 ft (0.91 m) cable. Non-monitored versions exist but are not recommended for primary entrapment protection on commercial doors.

Next step

If you are specifying a new door, call out the K72 in the safety device schedule — the cost delta is small and the coverage is double. If you are retrofitting an existing Manaras operator, confirm the BOARD070M revision and accessory power budget before ordering. For field support, troubleshooting, or installation in Metro Vancouver, contact CCGDS at (604) 206-5727.

INTERNAL_LINKS:

• [Commercial door safety devices explained] -> commercial-door-safety-devices-guide
• [Manaras OMH jackshaft operator] -> manaras-omh-commercial-operator-vancouver
• [Commercial garage door operator repair Vancouver] -> commercial-garage-door-operator-repair-vancouver
• [Photo eye and safety edge repair] -> photo-eye-safety-edge-repair-vancouver

FACTS_USED:

• Manaras MLC-K36 specs (3 ft height, 32 ft width, IP67, UL325, BOARD070M compatible, monitored) -> MANUFACTURER SPEC EXTRACTS LIGHTCURTAIN001
• Manaras MLC-K72 specs (6 ft height, 32 ft width, IP67, UL325, BOARD070M compatible, monitored) -> MANUFACTURER SPEC EXTRACTS LIGHTCURTAIN002
• CCGDS services Manaras operators -> Business focus: Works with commercial door brands: Manaras
• CCGDS contact phone -> Phone: (604) 206-5727