Film-Tech Forum ARCHIVE: Is there an easy way to simulate a lamphouse diode failure?

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Posted by Justin Hamaker (Member # 2165) on 08-07-2008, 02:50 AM:

I'm doing a training session on Saturday with my projection people and the main focus is going to be trouble shooting and problem solving. While I would not expect any of them to be able to change a diode, I would like to show them what happens when a diode fails.

I'm going to reiterate basic trouble shooting like checking breakers, fail safes, and power buttons; but I want to get into more advanced issues. I'm going to talk about things like loose parts on a brain, exhaust fan switches, what to do if you thread the wrong movie, how to use the media film cleaner, securing a print to prevent a throw, and whatever else I can cover in 2 hours.

For what it's worth, the training will be on the level of people who are competent at threading a projector, but are otherwise new to projection. A couple of the people know how to build up movies, all but one know how to tear down, but only one has had much experience dealing with real problems beyond missed fail safes or platter decks powered off.

As I type this, I'm really thinking diodes are more advanced than I want to get into. But I still think they should see what happens so they can better relate the info to me or a tech on the phone.

Posted by Monte L Fullmer (Member # 2797) on 08-07-2008, 04:40 AM:

quote: Justin Hamaker
I'm really thinking diodes are more advanced than I want to get into

Good assumption since this area is more complicated for a beginner to get into since it's dealing with a hazardous situation being around electricity. Plus, doing diode changeout is tricky in itself due to the right diodes have to be placed in their correct positions of positive and negative.

On diode failures: a simple test to tell them is to throw a bare light on the screen with machine running. If the light has a pulsating flicker, a good assumption would be that a diode has gone out and need experienced and QUALIFIED help in this area since that qualified individual will then do a very quick test of throwing a light on the screen with open dowser and shutter blade with machine off with lens removed since the light without a spinning shutter will not experience any pulsating to conclude the test of a bad diode (or a leg in a triple contactor within the console, or a leg in a triple breaker in the panel)

I'd just stay with a 4 level area of booth training to keep things on the simple side:

1-Knowledge of the basic operation of film handling with the machine, film transports and with proper presentations.

2- Make and break with all forms of filmwork with proper operations of MUTS, benches, et.al.

3- Preventive maintenance .. wiping and cleaning down machinery and associated components.

4- (optional) knowing how to do bulb changes and lamphouse/console maintenance.

Don't give them too much responsibility for the sake that they'll be under pressure to remember it all. Plus,if a thing or things go wrong, you're the "it" guy who'll get the final results from the top end.

Plus, if you do give them a lot to remember, then they'll expect pay to match such responsibiity and that could backfire as well.

Some tips and ideas ... - Monte

Posted by Louis Bornwasser (Member # 3063) on 08-07-2008, 05:17 AM:

Monte is right! Also, I have seen many cases where you then have to fix their work as well as the original problem.

Life safety issues: Would a reasonable man allow semi-skilled people to work on 3 phase equipment? Louis

Posted by Tim Reed (Member # 137) on 08-07-2008, 10:12 AM:

When troubleshooting with inexperienced operators, the way you phrase questions makes all the difference in the world:

"Is it strobing on the screen? Does it look like you're watching the movie in a dance club?"

But, if you really want to show them what it looks like, just disconnect one of the 3-phase lines going into the rectifier (with the main breaker off and safely capping the wire, of course) and then start everything up.

Posted by Gary Crawford (Member # 2038) on 08-07-2008, 10:17 AM:

I would also write up a manual with this training information in it, so they could refer back to it as needed. A lot of info will be coming at them all at once.

Posted by Louis Belloisy (Member # 3836) on 08-10-2008, 11:37 AM:

Not sure what type of rectifiers you guys are talking about.
We are using the XeTron rectifiers and when a diode goes south, there is no light. the lamp will not light. I have changed many diodes over the years, I will not allow one of the younger projectionists to open a rectifier. Its either myself or our technician.

Louis

Posted by Justin Hamaker (Member # 2165) on 08-10-2008, 01:42 PM:

We have XeTron and Christie lamp houses. I have also changed a number of diodes over the years. I did my training session yesterday and opted to not even discuss diodes.