Film-Tech Forum ARCHIVE: Strong DC ignitors and long bulbs

This is topic Strong DC ignitors and long bulbs in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Rick Long (Member # 213) on 02-16-2003, 08:25 PM:

Introducing the players:
Strong Highlight II console,
Strong 82-80005 switching rectifier,
Osram 3000 W/H bulb.
D.C. ignitor,(light grey box)

"Bulb won't light, but I can hear a ticking sound within the lamphouse"

(thinking: a ticking sound means he has sufficient DC voltage to enable the ignitor - so rectifier is probably ok), Is there a spark within the bulb?

"No"

Okay, check to see that the anode cable isn't touching or near anything grounded like the anode support base, reflector or even dowser.

"Nope, all is ok there."

Did you try your spare ignitor?

"Yup, still no go"

I hung up the phone and headed out.

The problem was described accurately. I could hear the ignitor firing, but the spark wasn't jumping the bulb.

Opening the non-operating side door, and by-passing the magnetic interlock with a small magnet, I activated the lamp on switch. It took a minute to see it, but there was indeed a spark - not across the bulb, but from the teflon negative adaptor to the edge of the bulb focus mechanism.

I removed the bulb and teflon adaptor. Except for some carbonization where the spark had been jumping, it looked fine. Cleaned it up and tried again.

Same story. The spark was jumping from the teflon (actually through the teflon) to ground.

The night shift projectionist walked in around that time. I showed him what was happening. Then he said the magic phrase;

"Ya know, I think we got another one of those things in our parts cabinet"

(Sometimes God is kind to old soundmen).

Replaced it, bulb stuck fine.

A few days later, when repeating this story, I had heard that sometimes the D.C. ignitors have a problem with long bulbs such as the 3000 W/H and the 3000 W/HS would be a safer bulb to use in this case.

Anyone else found this?

Posted by Keith Madden (Member # 910) on 02-16-2003, 09:30 PM:

Must have been something different about the set up after installing the spare adaptor if not the adaptor itself. Did you have your fingers crossed?

Posted by Mark Hathaway (Member # 1044) on 02-16-2003, 10:52 PM:

I have seen an ignition pulse jump through a teflon insulator, replacing the insulator is the best bet, as you discovered.

*Normally* tiny black spots can be seen where the ignition pulse is comming throught the insulator.

Mark Hathaway

Posted by Rick Long (Member # 213) on 02-17-2003, 12:29 AM:

Had fingers, toes, and other things crossed too. [Smile]

Upon later examination, i did find tiny black spots, damn tiny though.