This is topic Bypassing fuses? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by David Yauch (Member # 2754) on 11-18-2004, 03:19 AM:
 
Last friday when I was turning on projectors in the morning I noticed that the power led on the projector panel didn't light up on one of them. If the power LED is blinking thats always the sign that we need to change out or simply wipe off and re-position the fuse. The projector was on, since i could hear the vent from inside the lamphouse, but still no power LED. A quick check of the automation, and the start button does nothing. No failsafe alarm for trying to start w/out any film threaded as would be normal, just nothing. So I remove the fuse and notice the problem, the fuse cap was broken so that the fuse was sinking in too far and not making contact. It turns out a spring magically disappeared. We looked and looked but could not find the original spring or any sort of suitable replacement. Using another fuse cap worked just fine and the projector started normally so we decided to sacrifice the fuse cap from our lobby projector which does not actually show film until evening time when the lobby has darkened enough. I called our engineering department to see if they could bring a replacement and I was told it would be a couple weeks, but he knew a workaround so it was ok. I was pretty sure he was talking about manually starting the lobby projector for a couple weeks so I didn't think much of it until I talked to him later. He had me open up the projector panel, disconnect the fuse holder, and connect the wires going in to the fuse holder to each other. This worked just fine and the automation works as normal. The only difference is that sometimes you have to flip the power switch on the projector panel on and off to get the power to turn on. What I'm wondering is what drawbacks there are to bypassing fuses, since there must be SOME purpose to having them there in the first place, or we'd just skip them all together. So if anyone could shine some light on this I'd apreciate it.

In case it's needed, we're using cinemeccanica V5s.
 

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Posted by Andrew Shingleton (Member # 2257) on 11-18-2004, 05:00 AM:
 
I'd assume everything would run fine, unless something created a power spike or surge - then without a fuse to blow some other part of your equipment (a part far more expensive than the fuse was) would probably blow instead.
 

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Posted by Chase Hanson (Member # 2779) on 11-18-2004, 05:03 AM:
 
Well

As mentioned if you get an excessively high current draw through that line (thats what fuses are for), than you can kiss all your projector electronics good bye.
 

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Posted by Tom Sauter (Member # 616) on 11-18-2004, 07:20 AM:
 
I'm not exactly sure which fuse you're bypassing, but its dangerous to bypass a fuse. You can cause an electrical fire resulting in huge losses.

If your engineers can't get out there for a few weeks you should find an industrial electrician locally who can trace the problem and correct it immediately. Since you're just having to re-seat a fuse on a regular basis the fuse holder is likely worn or damaged and it should be a simple fix. There's nothing "special" about the fuseholders on a V5 console.
 

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Posted by Peter Hall (Member # 695) on 11-18-2004, 07:23 AM:
 
Hi

I've had Cinemec fuse holders fall apart, but bypassing should be a last resort. Sure, if you are sure that the fuseholder is the only problem then bypass as your own peril to get the show on, but any fuse is designed to be a "weakest link" and protects the wiring and circuitry. Removal could create a fire risk - I'd replace the fuse ASAP - I agree that some gear is overprotected but you are playing with fire (maybe literally, and maybe not immediately) if you short these long term
 

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Posted by Dominic Espinosa (Member # 2122) on 11-18-2004, 12:40 PM:
 
I'm not an expert on the subject but couldn't you just replace the fuseholder with an inline fuse or something in the interrim until the replacement shows up?
I'm sure you could get something close enough at radioshack or from grainger if neccesary. no?
 

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Posted by Chase Hanson (Member # 2779) on 11-18-2004, 01:39 PM:
 
You could probably run to a local autoparts store (Autozone, Kragen/Checkers, Napa, etc.) in their electrical section they will have a "fusible link" for both Maxi and barrell fuses. Costs about $2-$3 and all you would need is to solder it in place or use crimp/posi splicers.
 

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Posted by Randy Stankey (Member # 64) on 11-18-2004, 02:32 PM:
 
I tend to agree that, under "normal" conditions, bypassing a fuse wouldn't pose a great threat PROVIDING it's only a temporary measure to keep the show on the screen until a permanent repair can be done.

However, we all know that, in this business, "temporary" often means "permanently temporary". I, myself, have fallen into that trap where you make a "quickie" repair and say to yourself, "I'll fix it up the right way tomorrow..." The problem is that, "tomorrow" comes and goes many times and the quick fix still hasn't been made right.

Then, one day, the machine goes up in smoke and you discover the "temporary" fix that caused the whole mess. The first thing that comes out of your mouth will probably be, "What kind of IDIDOT did this!?"

Only, this time, the IDIOT was YOU!
 

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Posted by Ron Yost (Member # 1850) on 11-18-2004, 03:28 PM:
 
Radio Shack has fuseholders for just about any fuse type. They're certainly not the 'best' quality, but at least they'll work properly and safely, especially if you don't have to change the fuse very often.

Go to radioshack.com and type 'fuse holder' in the search box to see what they have available.

I sure would NOT use a fusible-link intended for a car!!!

Ron Yost
 

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Posted by David Yauch (Member # 2754) on 11-22-2004, 09:50 PM:
 
I'm pretty much stuck in this situation with whatever the engineering dept. tells me to do. Basically everything they said was logged multiple times so the responsibility doesn't fall on my shoulders. The best I can do, and will do, is to pass the information I've received on to senior management at my own theatre and see what else can be done.

I don't like the whole situation, but I didn't have much choice in the matter.
 

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Posted by Gordon McLeod (Member # 33) on 11-22-2004, 10:52 PM:
 
Unless one is qualified to make that decesion to bypass the fuse one shouldn't do it
If one does even on instructions of upper management the person who did it can still be held liable if an accident occurs causing a fire or injury so proceed with caution

as a side note automotive fuses are usually not rate for the voltages that may be encountered and as such may actually establish an arc internally and continue to conduct
 

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Posted by David Yauch (Member # 2754) on 11-22-2004, 11:20 PM:
 

quote: Gordon McLeod

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Unless one is qualified to make that decesion to bypass the fuse one shouldn't do it
If one does even on instructions of upper management the person who did it can still be held liable if an accident occurs causing a fire or injury so proceed with caution

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quote: Michael Schaffer

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Did you know that your last name means "animal sewage, manure" in German?

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