Dumpster dive video projector help... lamp or ballast? - Page 1
Forum section: electronics / repair

author: Robomeds
author_rank: Frequent Contributor
timestamp: June 27, 2016, 05:35:59 am
content: Well I had a decent bit of dumpster diving recently. I picked up two video projectors, both older Canon models. One was marked "bad" but seems to work just fine. I used it for about 30 min via the VGA port. The other is a Canon SX7 that was marked as "needs service". When I power the thing up I get a flashing warning light. Per the manual, two flash indicate either a bad bulb or a bad ballast.http://www.manualslib.com/manual/25113/Canon-Sx7-Markii.html?page=126Well, it might be worth getting a new bulb if that's the issue. However, at ~$250 I'm not sure I want to guess and check. A "pulled from working" power supply/ballast is $40. That's easier to swallow but I think I would still like to have a better idea before spending the money. I believe the SX7's were used as installed conference room projectors. The AV center would almost certainly have had spare bulbs on hand as replacements for these projectors hence I would guess we aren't dealing with a bad bulb... but I would like to check before spending any money.OK, so with the cover off I've tried starting the projector. The lamp starts to glow and I hear a series of ticking sounds. The sounds remind me of old florescent lamps starting. There is a glue-white glow coming from the bulb that dies out when the ticking goes away. I'm not really that familiar with how 3 wire halide projector bulbs are started. In any case the system trying but failing to start the bulb yet it can produce a glow.Anyone familiar with these systems? What should I look for and conversely, is there a way to tell if the lamp is bad via inspection (it doesn't look bad based in that it looks like it hasn't baked the glass too much). I've looked at a few old lamps and they typically look like they have a number of hours. Anyway, this one looks good but I'm not certain. The start up process does something but not much. I'm tempted to just get the power supply/ballast on the assumption that the AV dept would have tried a new bulb first. I would be hard to justify the lamp even if I know it's the problem. This was an expensive projector back in the day but 1080 projectors are now rather common. It makes it hard to justify spending much on this one.Any thoughts?

author: BMack
author_rank: Regular Contributor
timestamp: June 27, 2016, 08:21:04 am
content: Besides a shattered lamp or broken filament(which can be hard to see because of the reflection). If there is a crack in the ceramic on the rear of the lamp, it's bad. Also if it's cloudy on the metallic part or if there's a bulge in the stem, it's bad or going bad.I haven't worked on a ton of projectors, maybe a couple dozen (mostly DLP) but based on that experience...Don't count on them having extra replacement lamps as a way to say that it's a ballast. A lot of places see the price of a generic lamp and a factory original, then buy the generic. With generic lamps, sometimes they work(for a short time), sometimes they sort of light as you're describing and sometimes they don't work at all.Are the lamps in either projector the same? It's possible they are the same lamp but in a different housing.

author: Robomeds
author_rank: Frequent Contributor
timestamp: June 27, 2016, 09:30:57 pm
content: After spending a bit more time looking at the bulb and some pictures on line I'm guessing the bulb is in fact bad. Now do I want to spend $230 for a new bulb given the risk that there may be something else wrong with the projector.The SX7 is a very good, older model. LCoS light engine thus you basically don't see the spaces between pixels. Good color quality and this is a 4000 lumen (presentation mode), 1400x1050 projector. However, it lacks lens shift and some other features of true HT projectors. Kind of a hard call since $220 would be a good price for the unit if it works... if.The other projector is also nice and SXGA+ but only 2000 lumen (presentation).