Lamp‑Based BenQ Projector Repairs – Wells Electronics
Wells Electronics • Technical Guide

Lamp‑Based BenQ Projector Repairs

This page focuses exclusively on lamp (UHP) BenQ projectors (MS/MX/MW/MH/W/TH and certain TK variants). It covers a field‑tested checklist of symptoms, a structured troubleshooting flow, and the most common error indicators you will encounter on these models.

Typical Symptoms of Lamp‑Based BenQ Models

Image / Light Symptoms

  • Dim or yellow/green‑biased picture after warm‑up → lamp near end‑of‑life or optics dust.
  • Flicker or multiple strike attempts on power‑on → fatigued lamp or ballast ignition instability.
  • White spots / “starry sky” that multiply over time → DMD failure (stuck micromirrors).
  • Rainbow artifacts and/or whine → colour wheel bearing wear or sensor timing error.

Noise / Thermal / Power

  • Loud ramping fans and sudden shutdowns → clogged ducts, failing fans, or bad temp sensor.
  • “Overheating” message while fans spin → burnt fan controller ICs or invalid tach feedback.
  • Will not power / standby only → PSU rails out of spec, fuse/NTC, or mainboard short.
  • Intermittent HDMI / HDCP handshakes → loose connector, ESD array or retimer issues.

Tip: Note when the symptom appears (cold start, after 10–20 minutes, or only at high brightness). Timing often points directly to the failing subsystem.

Step‑by‑Step Troubleshooting Guides

Lamp Will Not Strike / Projector Cycles On–Off

  1. Record lamp hours. If near rated life, fit a known‑good lamp (avoid unbranded bulbs).
  2. Inspect the lamp housing: look for arc tube darkening, cracks, or deposits.
  3. Check the lamp door switch and interlocks; reseat connectors.
  4. Scope ballast output during ignition; verify proper waveform and duration.
  5. Clean intakes/filters; confirm fans reach target RPM before strike.
  6. After replacement, reset lamp hours and perform brightness/colour checks.

Fan Noise, “Temp” Warning, or Thermal Shutdown

  1. Blow out dust away from the optics; visually inspect ducts and heatsinks.
  2. Read tach feedback in service menu (if available); replace slow or rattling fans.
  3. Test PWM/TACH lines to the controller IC; if fans spin but tach reads invalid, replace the controller board/IC.
  4. Verify thermistor sensors with a DMM; replace if drifted.
  5. Re‑paste key heatsinks (DMD, power semis); confirm stable temps during a 30‑minute soak.

White Spots / Stuck Pixels (DMD Failure)

  1. Confirm on multiple inputs/resolutions; the artifact is panel‑level, not signal‑level.
  2. Inspect for dust on optics; if spots stay perfectly fixed frame‑to‑frame, proceed.
  3. Replace DMD with correct part code; observe ESD precautions and torque specs.
  4. Re‑seat heatsink with fresh thermal compound; verify uniform focus and geometry.
  5. Run a full‑field grey and colour uniformity check; log results.

Colour Wheel Noise / Rainbowing

  1. Open access and listen at low brightness for bearing whine or scraping.
  2. Check the Hall sensor signal; if unstable, replace wheel and align timing.
  3. Ensure no cable rub or debris in the wheel shroud; reassemble and test for artifacts.

Common parts you may encounter: UHP Lamp Ballast Colour Wheel Fan(s) Fan Controller IC DMD Mainboard PSU

Error Codes & Indicators

Wording varies by model; always note LED colour/patterns in addition to on‑screen text.

Indicator / MessageWhat It Usually MeansNext Step
Lamp Warning / Replace Lamp Lamp at end‑of‑life or ballast misfire Check hours; fit known‑good lamp; test ballast ignition
Temp Warning / Overheating Dust blockage, failed fan or sensor Clean ducts; verify fan RPM; test thermistors; re‑paste heatsinks
Fan Error / Fan Lock No/invalid tach signal Replace fan; inspect fan controller IC and cabling
Warning LED patterns only Firmware/PSU protective trip Capture LED colours/pattern; perform power/rail checks; read logs
White Spots on Image (not a code) DMD failure – stuck micromirrors Replace DMD; verify cooling and optics cleanliness

When to Book a Repair

If symptoms persist after the above checks—especially repeating strike failures, thermal shutdowns despite clean airflow, or growing white‑spot clusters—professional bench diagnostics are recommended. We provide fixed‑price quotations, parts‑and‑labour warranty, and return shipping across the UK & Ireland.