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Author Topic: (RESOLVED) FP-350 - wire breaks off Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 01-29-2009 05:15 AM                     "Yo!" Once again, it's my turn to holler for help on a situation that loves to occur from time to time without rhyme or reason... ..and this is on our "dearly beloved", STRONG FP-350 detectors: (I prefer the SPECO ones myself that comes on CHR P35 units..) For some odd reason or another, a wire will actually break right off at the pinch connection of these detectors without any notice, without any physical contact - like they got a mind of its own to wanna break when they feel like it. Course, when this happens, it sends the automation in an open loop condition and will not operate - operation has to be done in manual. Anyone out there with these danged things have/had the same experiences like this one? This is the 2nd incident that happened this week with these danged detectors....on different machines. EDIT: Thx to all for your help thx-Monte [ 01-29-2009, 02:38 PM: Message edited by: Monte L Fullmer ]  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 01-29-2009 06:24 AM                     "Word up, homie!" It's difficult to tell from the photo, but it looks like the stripped end of the wire that came off is exposed. If that's the case, the wire didn't so much as break off as it simply came loose from the terminal. I would check to make sure all the terminals are nice and tight. And if it did actually break off, simply strip back some more of the wire, stick it back in, and tighten down the screw. As for getting back on screen if this happens in the middle of a show, simply press Fault Defeat (I'm assuming here that you have a CNA automation) on the automation. This bypasses the failsafe circuit completely and allows you to continue to run in case of any problems with the failsafe. Just be careful, because the automation will not shut down if there is a brainwrap or other condition where it normally would.  |  IP: Logged Kenneth Wuepper Phenomenal Film Handler Posts: 1026 From: Saginaw, MI, USA Registered: Feb 2002 posted 01-29-2009 06:47 AM                     Monte, Looking at your photo, there are several possibilities for this failure. There is no strain relief for the fail safe cable so the contacts receive all vibration and motion flexing from the cable. The cable is drooping down where the operator can bump it while threading the fail safe device. Flexing the wires at the point of attachment will eventually cause them to break. This can be corrected by a tie wrap around the cable and to the opening by the adjustable mounting screw at the top of your picture. Excessive tightening of the terminal screw can eventually weaken the wires that are trapped beneath the screw. The screw may also have a sharp edge to assure a good grip on the wire and that when over tightened will eventually cut through a wire. KEN  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 01-29-2009 07:16 AM                     We normally dress the cable with ty-raps to the bracket for a strain relief. Many of those connectors have a contact spring that the screw contacts to put pressure on the wire; these need to be "squared up" in the hole so that the wire will seat fully instead of pinching a part of the copper. On new installs we use ferrules (a small sleeve slipped on the wire and crimped on) to have a better bond...  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 01-29-2009 07:55 AM                     I've found that many failures like that happen because the production worker (or whoever) stripped the wire without using the 'limiting' feature on the stripper to prevent nicking the wire. Also, for that application, stranded wire should be used (the wire in the photo looks solid.) I used to fold the end of the wire over when possible, so 'twice' the gage was clamped by the screw terminal.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-29-2009 08:00 AM                     quote: Monte L Fullmer (I prefer the SPECO ones myself that comes on CHR P35 units..) Those SPECOs sucked big time! I've replaced every single one I've ever come in contact with. The drop arms are hung on the thing backwards and will catch on an area of film that could be missing or torn open and it makes the damage to the film even worse. and the PCB is very unreliable. Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-29-2009 11:31 AM                     bad wire stripping is often the culprit I also usually tin the wires before inserting them in the terminal tip Also a strain relief to keep the weight of the cable and vibration is a good idea  |  IP: Logged Andrew Bangs Expert Film Handler Posts: 148 From: Kerrville, Texas, United States Registered: Sep 2008 posted 01-29-2009 11:46 AM                        I would suggest Tinning the wire as well. While it was not in this situation but another I had in a different career. I had to tin the wire so that the solder actually flowed back into/under the the remaining insulation about a 1/4 or 1/8 inch. This helped tremendously. Especially if it is a spring loaded catch as this makes the wire more firm to push in.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 01-29-2009 01:10 PM                     "Wow!" ...And tonnage of thx on all of these suggestions! Definitely got my chore cut out the next time I visit this theatre to apply these suggestions in correcting this little problem. quote: Ken Lackner (I'm assuming here that you have a CNA automation) on the automation. I wish, but got dinosaurs here: SPA7's -THX Muchly - Monte [ 01-29-2009, 02:40 PM: Message edited by: Monte L Fullmer ]  |  IP: Logged John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 01-29-2009 11:16 PM                     I thought you were not supposed to tin wires before holding them under compression, because you were more likely to get metal fatigue. (This is why, if you are going to crimp-and-solder terminal lugs, you should crimp first, and then solder with a solder pot, not an iron.) Does that not apply here? --jhawk  |  IP: Logged Andrew Bangs Expert Film Handler Posts: 148 From: Kerrville, Texas, United States Registered: Sep 2008 posted 01-30-2009 12:25 AM                        Honestly I never heard that before... Interesting you learn something new every day. I don't know why it would lend to metal fatigue especially if it is a connection that is only supposed to sit there. Now if it were something being attached and detached regularly then perhaps but on a permanent connection I don't really see the harm. But that is just me.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 01-30-2009 05:08 AM                     quote: John Hawkinson ...and then solder with a solder pot... ...and how many of us have access to a solder pot anywhos? I know what that device is - great for tinning wires when you first dip the wire in flux then the wire gets dipped in the molten solder (nowdays, it's the ROHS lead free stuff..), then put to work.. -Monte  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-30-2009 08:19 AM                     Generally speaking...soldering wires are a bad idea when the wires are to be flexed. the point where the wire transitions from the wicked solder to no solder becomes a point of failure and will break. Likewise, crimping a solid wire is a very poor connection and the crimping process itself can often weaken wire if not have a failure from the get-go. You can cut solid wire with rather dull cutters, yet stranded wire does not cut so well or will be very ragged if cut with dull cutters...think of the crimp area as a dull cutter (very dull). Now crimping stranded wire, then soldering has merit. The cimping will create a molecular bond between the terminal and the wire. The crimp will also immobilze the wire strands. By soldering after crimping, each form of connection augments the other. However, again, you don't want to let the solder wick up the wire past the crimp point. As a certified reconer for speakers, I can tell you, one of the things that you get inspected on is when you make your tensil lead connections to the terminals on the basket. Solder is not to be allowed to wick up the lead to avoid the lead breaking...as such, one has to make these connections quickly to keep the heat localized. For the wires to be breaking in Monte's case...I'd think that it is low strand count wire, and/or the wire was prepped poorly from the very beginning. Steve  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-30-2009 08:35 AM                     I agree with Steve on tinning wires. I've found just that problem over the years AND tinned wires seem to suffer from compression set over the years... they need to be re-tightened. I've seen them literally fall out of those screw terminals on occasion. Likewise, I always laugh at the installer that also uses spade crimps on screw terminals that already have compression squares under each screw . Solder pots are very handy for tinning enamled wire... it also removes the enamel cleanly. Mark  |  IP: Logged Robert Minichino Master Film Handler Posts: 350 From: Haskell, NJ, USA Registered: Dec 2005 posted 01-30-2009 01:56 PM                        I agree, don't solder wires to be crimped or clamped as solder has particularly bad cold flow properties, where it doesn't just take a compression set but actually migrates away from where the pressure is applied over time. If you want to put stranded wire into a phoenix connector or similar and you don't want to worry about getting all of the strands in, use a crimp-on pin or ferrule. It neatens up the wire end and the crimp sleeve won't have the cold flow problems a solder-tinned wire end would have. If you want to stop solder from wicking up a stranded wire, one of those cheapo clamp-on heatsinks works pretty well.  |  IP: Logged

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