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This topic comprises 2 pages: 1 2
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Author
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Topic: Xenon bulb must be manually struck
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Dave Macaulay
Film God
Posts: 2321
From: Toronto, Canada
Registered: Apr 2001
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posted 06-04-2007 09:36 PM
Auto ignitors all work pretty much the same. When the lamp is on, the lamp voltage is 25 volts DC or so. With the lamp not struck but the rectifier on, the voltage is quite a bit higher - 80 volts up to 150 volts depending on the type of rectifier. The autostrike circuit just senses the higher voltage and tries to strike the lamp until the voltage drops which indicates the lamp is on. Christie ignitors do it all in the ignitor case, older Strong systems have a separate autostrike circuit board. Different brands do it either way. The voltage sensing circuit operates a relay to switch the AC power to the ignitor itself. Christie also has a time delay relay which stops the ignitor after a second or three and waits five or ten seconds before trying again, this prevents the ignitor from burning out. The high voltage transformer feeding the tesla coil circuit isn't designed for continuous operation, it would burn out pretty quickly if the ignitor didn't have the cool-down time imposed by the time delay unit. Since your ignitor works on manual, the problem is with the autostrike part. The relay is most likely, the time delay less so, and the zener diode could have failed also. Older ignitors have a time delay that looks a bit like a radio tube, in a socket. Newer ones use a black plastic box soldered in inside the case. The nasty big warnings on the ignitor case cover are to tell you it can kill when it's powered. There's no danger in the ignitor if the AC supply is shut off, but there may be dangerous DC voltage on all the lamp wiring for a few minutes after shutting off if the rectifier was ON without the lamp striking. DO NOT try bench testing the ignitor unless you really know what you're doing.
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