How a cheap lamp became a ₹8,500 repair
Short answer: A training centre purchased a projector lamp advertised as "original OEM" from an online marketplace seller for ₹3,200 — approximately 40% below the authorised distributor price. The lamp failed at 47 operating hours and the abnormal ignition voltage it drew during that period burned out the ballast driver stage. Total repair: ₹8,500. The discount on the lamp cost them more than three times the savings in secondary damage.
The projector arrived with no image output and no lamp indicator blink. This combination — a projector that powers on, fan spins, but no lamp strikes and no LED blink code — immediately directed the bench team to the ballast rather than the lamp. The failed lamp was still installed. When examined under magnification, the lamp bulb showed darkening at one electrode end consistent with premature arc erosion — the kind of erosion that happens when a lamp is driven at a voltage it was not designed for.
What a grey-market "OEM" lamp is
The refurb cage technique
Genuine OEM projector lamps — Epson ELPLP series, BenQ 5J series, Optoma SP series — consist of a UHP (Ultra High Performance) mercury arc bulb mounted in a precision-moulded plastic cage with integrated reflector. The cage is model-specific and positions the bulb arc at the exact focal point for that projector's optical system. Grey-market operations source used authentic cages from failed genuine lamps and install a remanufactured or substitute bulb with incorrect arc geometry. The cage passes visual and part-number inspection. The bulb does not perform to spec.
What wrong arc geometry does to the ballast
The arc gap — the distance between the two tungsten electrodes inside the bulb — determines the ignition voltage required and the sustaining voltage during operation. A lamp with a wider-than-spec arc gap requires more voltage to strike and sustain the arc. The ballast compensates by increasing output, but this pushes the driver circuit beyond its design envelope. Over 47 hours of operation, the MOSFET switching stage in the ballast driver ran consistently above its rated dissipation, eventually failing under thermal stress. The lamp and ballast failed within days of each other.
The bench confirmed the root cause by measuring the arc gap of the failed lamp under magnification: visibly wider than the specification for this model. A new genuine ballast driver board: ₹5,200. Genuine OEM replacement lamp: ₹5,800. Diagnosis: ₹500. Total: ₹11,500. Had the customer purchased a genuine OEM lamp at the authorised price of ₹5,500 to begin with, the ballast would have been undamaged and the total cost would have been the lamp price alone. For a complete discussion of how lamp quality affects projector longevity, see the three-lamp-swaps ballast crack story. The guide to projector lamp replacement lists the OEM part codes and authorised sourcing approach for every brand we carry. To get a lamp authenticated or a ballast checked in Hyderabad, WhatsApp model and purchase details to 7702503336.
How to verify a projector lamp is genuine before installation
Three checks that take under two minutes
First: confirm the seller's invoice shows the manufacturer's authorised distributor name and a GST registration number. Epson, BenQ, and Optoma each have a small number of authorised lamp distributors in India — their names are on the manufacturer's website. A cash receipt or no invoice is an immediate red flag. Second: check the part number on both the cage label and the bulb itself. On a genuine lamp, the part code is typically laser-etched or printed on the quartz envelope of the bulb, not just on the external cage label. On a refurbed grey-market lamp, the bulb may be unmarked or show a different code. Third: verify the holographic authentication sticker on genuine OEM lamps for Epson and BenQ — it changes colour when tilted. A flat-colour sticker that does not shift is not holographic and is not a genuine authentication mark. A 40% discount versus the authorised distributor price is a reliable indicator that something is wrong with the supply chain.