Richardtr3a Posted October 20, 2013 Report Share Posted October 20, 2013 As a fairly novice electrician I have a problem with my two front mounted spot lamps. These are mounted on a bar at the front of the grille. I used a four terminal relay attached up under the front panel bar. I understand that the relay is really a switch which will, when activated connect the main cable to the accessory. I took a cable from the regulator terminal A in the same size as the existing cable on terminal A, up to the relay and on from the relay to each spot lamp which was then earthed back to the earthing clamp inside the engine bay. This does not become a live connection in the relay until activated. I took a cable from the high beam headlamp feed behind the headlamp to the relay switch which was earthed through the pull switch on the dashboard. So this would only be live when the headlamps are on full beam and the pull switch operated. I may have failed to understand this in some way. The spot lamps worked well for some time. However they both failed to operate at the same time, and after some investigation it appeared that the units had become very hot and melted the rubber grommets which prevent the reflector from vibrating. After cleaning up the contacts the lamps worked for a few minutes in the garage, until one lamp packed up. The cable to it is live and a new bulb should work. I used a heavy cable for the feed, brown with a white stripe. I imagined a water analogy and that a smaller cable might not be able to cope. Why have my lamps heated so much that the contacts need cleaning and the rubber spacers melted? I am sure that there is a member who understands the demands of the lights and can help me with the correct repair. Thanks Quote Link to post Share on other sites
RogerH Posted October 20, 2013 Report Share Posted October 20, 2013 Hi Richard, what is the wattage of the each spot bulb - 60watts = 5 amps. Most cable will survive this current. The heat inside the lamp could be caused by a dry solder joint or a high resistance joint. Disassemble and inspect all the joints. If there are any solder joints resolder them. Roger Quote Link to post Share on other sites
AlanT Posted October 20, 2013 Report Share Posted October 20, 2013 What kind of lights are these? Post a photo. Your wiring method seems OK. There must be somthing wrong with these lights. Are you sure you fitted the right kind of bulb. Quote Link to post Share on other sites
Richardtr3a Posted October 20, 2013 Author Report Share Posted October 20, 2013 The bulb fits the Lucas spot light and is a single filament 48 W. There does not seem to be any damage to the cables or connections. however the end of the actual bulb looks as if it has been soldered and has become very rough. It does seem to have overheated and melted slightly. The rubber grommets have also melted and the actual cables seem to be fine. Something is not right because these are old lamps and were perfectly in a previous life. Thanks Quote Link to post Share on other sites
AlanT Posted October 20, 2013 Report Share Posted October 20, 2013 Just get two new bits of wire and connect one lamp straight to the battery. Simplest possible circuit. Cant go wrong. The bulb isnt making a good contact in the lamp somehow. Fiddle with contacts until it runs OK. Quote Link to post Share on other sites
Richardtr3a Posted October 21, 2013 Author Report Share Posted October 21, 2013 The next stop is to fit new lamps and try to find new rubber grommets. Is it possible that my cable is too big and allowing too much current? I am a novice electrician! Thanks Quote Link to post Share on other sites
littlejim Posted October 21, 2013 Report Share Posted October 21, 2013 The next stop is to fit new lamps and try to find new rubber grommets. Is it possible that my cable is too big and allowing too much current? I am a novice electrician! Thanks It only lets through what the lamps need to operate. bigger is better than too small. Quote Link to post Share on other sites
AlanT Posted October 21, 2013 Report Share Posted October 21, 2013 I'll try again. The spring contact that touches the bulb is not bright and shiny and does not touch the bulb hard enough. Clean it and bend it. Nothing to do with wire at all. Quote Link to post Share on other sites
Richardtr3a Posted October 23, 2013 Author Report Share Posted October 23, 2013 There is a lot of discussion about LED lamps and I am wondering if they exist in the right size for my lights. If they do will they run cooler? thanks Quote Link to post Share on other sites
RogerH Posted October 23, 2013 Report Share Posted October 23, 2013 Hi Richard, LED lights will run cooler as all the current goes to making light whereas with a filament bulb 90% of the current goes to making heat. However LED lights have their own problems - direction, spread, cost, availability. Roger Quote Link to post Share on other sites
Richardtr3a Posted October 23, 2013 Author Report Share Posted October 23, 2013 Thanks Roger. I will be looking out at the Restoration Show. Quote Link to post Share on other sites
Don H. Posted October 24, 2013 Report Share Posted October 24, 2013 Hi Richard, LED lights will run cooler as all the current goes to making light whereas with a filament bulb 90% of the current goes to making heat. However LED lights have their own problems - direction, spread, cost, availability. Roger Roger, I'm assuming your comments are about LED bulbs in general. A Lucas SFT foglamp will take a 323 bulb (transverse filament) with P36s (BPF) base. I'd be shocked sh**less if there were an LED upgrade for this -- I sure don't know of one. There are many, many LED auxiliary lamps, fershure, but they're all made that way from the start and I've seen none that look "classic". Richard, you noted your lamps are "old". Are the lamps original Lucas bits or the more recent (relatively high quality) reproductions? I'd expect the little rubber bumper on the clamp for a Lucas original to be made of a real rubber compound. In this case it will not melt -- rubber is a crosslinked thermoset polymer and it will char but not reflow. I guess there's a chance Lucas used a thermoplastic elastomer, but that would have been rare for the day and more likely for a modern product. I've found those bumpers in the new lamps to be soft and a bit squishy -- I have one that's deformed and stuck to the glass (as if melted) from a lamp that's never been turned on. Questionable material choice in my opinion. Photos of yours would be useful. It might be that your light's temperature is not the cause of the "rubber" of the bottom front clamp melting. When you state the lamps "packed up" does that mean you're repeatedly seeing bulbs burning out? I'd start looking for a short someplace that would allow an overcurrent situation until the bulb acts like a fuse and shuts off flow. Quote Link to post Share on other sites
AlanT Posted October 24, 2013 Report Share Posted October 24, 2013 Dont suppose you could somehow have 6volt bulbs in these? Buy some new bulbs and keep trying. Quote Link to post Share on other sites
RogerH Posted October 24, 2013 Report Share Posted October 24, 2013 Hi Don, LED's in general. Roger Quote Link to post Share on other sites
Don H. Posted October 24, 2013 Report Share Posted October 24, 2013 Yes, you're exactly right, Roger -- LED lighting for vehicles in general, including auxiliary lighting, is making fast progress. Here, for example, is one of the new style of LED lamps: http://www.expeditionportal.com/expedition-gear/accessories/1611-stuff-and-things-arb-intensity-led-lights.html There are all kinds of sizes and shapes -- small squares, wide rectangular bars, large pancakes. LEDs aren't immune to heat, although for the power they put out a lot less than incandescent. The really bright ones normally have significant heat sinks built into the housings. They even have multiple-LED array headlamp conversions for the 7-inch headlights on cars like out TRs. They're kinda weird lookin' though, and definitely not vintage-styled. Quote Link to post Share on other sites
Richardtr3a Posted October 25, 2013 Author Report Share Posted October 25, 2013 Don, Thank you for the input. This seems to be a possibility. Both lamps are at least 40 years old and are original. I wired them through a relay which is under the bonnet rail. They both stopped working and after dismantling the lights I found damage. I was intending to replace the relay and after moving it slightly one lamp came on. The other glimmered a bit and then blew. The point of the bulb looked as if the solder had become soft and was rough and unfinished. The connections to the relay are crimped and only a few years old, maybe 10 years. The rubber stops may have degraded through age. Thanks for your help. Quote Link to post Share on other sites
Rodbr Posted October 25, 2013 Report Share Posted October 25, 2013 Quote "I wired them through a relay which is under the bonnet rail." Where exactly have you attached the relay? Unclear what you mean by "under bonnet rail". Hopefully not to the cross beam support under the front apron? Run a temporary earth wire from the battery directly to the relay attachment screw and then try again. Make sure you have a good clean connection! Quote Link to post Share on other sites
bigmalcy Posted October 25, 2013 Report Share Posted October 25, 2013 Where exactly have you attached the relay? Hopefully not to the cross beam support under the front apron? Rod - curious why this would not be a good location? Assuming you mean the square section bar which spans between the inner arches: this is where I've put the relay for my headlamps... thanks for the pics via e-mail btw! Quote Link to post Share on other sites
Rodbr Posted October 25, 2013 Report Share Posted October 25, 2013 check you mail, did you get the pics I sent you? Quote Link to post Share on other sites
bigmalcy Posted October 25, 2013 Report Share Posted October 25, 2013 Yup, thanks Rod - and for the benefit of others, Rod's concern with the cross beam is that it may not provide a good earth due to material / paint... but in my case the relay has an earthing wire which I've connected to the horn mounting bolt, so the cross beam is purely for physical mounting, no electrical purpose. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 25, 2013 Report Share Posted October 25, 2013 (edited) Went out in Brothers TR3A on Tues eve in the rain to the Winchester talk by Ian C on 4 VC. It was pleasing to have the road ahead lit properly. He has only a pair of Lucas H4 halogen lamps driven by an alternator. A decent dip beam is a must on the roads today as everyone is intent on blinding you as they dash about. Where I put my relays - Green things on the back of the Mcyl box cover plate. The cabling links into the dip switch out cables, the main power comes from a fused battery connection. The switching power is drawn from the dipswitch out terminals. Truthfully the spots only really serve the purpose of filing up the holes in the lamp bar. They work nicely adding light to the road but only on full beam. Peter W Edited October 25, 2013 by BlueTR3A-5EKT Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.