Keeping a Zoom Focus Gobo Projector Bright Year After Year

Why output fades quietly

A zoom focus gobo projector does not fail, it fades. Output declines slowly through dust, film on the optics and gradual LED wear, and because the change is gradual nobody dates it. By the time somebody complains the unit has often lost a third of its output — most of it recoverable with a cloth.

1. Take a reference photo at install, under the conditions it will run in
2. Repeat it annually, same hour, same house lighting
3. Log any cleaning or gobo change with a date
4. Compare before assuming the unit has failed

How to clean without damaging coatings

Clean in the order the light travels: outer window, then the lens, then the gobo. Use a blower or a soft brush before any liquid, and only then a lens cloth with a drop of isopropyl — never a household cleaner, which will damage coatings in one go. Handle the gobo by its edge; fingerprints bake into the coating under a hot lamp.

1. Blow or brush off loose dust first
2. Use isopropyl sparingly on a proper lens cloth
3. Avoid household cleaners on any coated surface
4. Handle the gobo by the edge, never the face

When the image, not the lamp, is the problem

Inspect the gobo whenever the image quality changes. Look for crazing in the coating, cracks at the edge, or a mark that appears in the projected image but is hard to see on the glass — holding it up to a light at an angle reveals most faults. Replace rather than clean a coated gobo that has started to degrade.

1. Inspect against a light at an angle for cracks and crazing
2. Look for marks that show in the image but not on the glass
3. Replace rather than clean a degraded coated gobo
4. Record the reference code for exact reorders

The half-yearly inspection

Twice a year, check the things that cause failures: housing temperature after an hour at full output, the condition of the seals and gaskets, the tightness of the bracket, and the state of the cable gland. A zoom focus gobo projector that is running hot, or whose gland has perished, will fail long before the LED reaches its rated hours.

1. Housing temperature after an hour at full output
2. Seals and gaskets still seated and supple
3. Bracket tight and the unit still on aim
4. Cable gland intact and the drip loop in place

Seasonal and event checks

Before the busy season, run the unit for a full evening rather than a few minutes. Thermal cut-outs and driver faults appear after an hour or two, not in the first five, and discovering that on the first night of an event is the expensive way to find it.

Spares worth holding

The spares list is short because the failure modes are few. A spare glass gobo covers image damage; a spare control handset covers the most common support call; a recorded artwork reference covers everything else. Keep them together with the install record.

• A spare gobo, cut from the same artwork file
• A spare control handset or remote
• The artwork reference and reorder contact
• The install record with throw and settings