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ratchetknee
USA
35 Posts |
 Posted - 03/04/2010 : 17:01:56
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| hey fellas, dusting off the winter cob webs on my 71 tr6r and i,m blowing headlight and tail light bulbs as fast as i can change them out. I,ve ran and re-ran the wiring to check for shorts,bare or chaffed wires etcetc. any ideas. Getting pretty expensive on a poor ole boy ya know. Yeah, good ole lucas system. At one time the main wire to the headlamp completely fried. Have changed out two zenor diodes and one rectifier so far, no change. |
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rwarner
USA
351 Posts |
Posted - 03/04/2010 : 21:40:23
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Hello All;
Mr. knee, I am no expert! But my experience tells me to check the battery condition, the test at http://www.gabma.us/page2.htm, then the charging system with a multimeter.
Others will be along to add to the possibilities.
Bob
'68 T120R |
Edited by - rwarner on 03/04/2010 21:41:12 |
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peterk
United Kingdom
76 Posts |
Posted - 03/05/2010 : 06:48:56
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Hmm,
Further to Bob's advice:
The usual cause of damage to lamps/bulbs is either vibration or overvoltage. One test would be to check battery voltage with a multimeter and rev the bike - see if the voltage shoots up past around 13v. If it does I'd suspect the zenor. Now I know you've changed it and assuming you have a healthy one installed - it might be worth double checking that its connected properly?
Pete |
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JubeePrince
USA
796 Posts |
Posted - 03/05/2010 : 07:24:10
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I'm with Peter -
Check the Zener or regulator.....
Ratchet -
You can throw parts and money at the bike all day.....have you actually tested the components as outlined in the manual? Not trying to be a smart-a$$  , it's just that with electrical problems, you need to be scientific and logical in your approach.....
Steve
'77 T140J
"Vintage Bike" What's in your garage?
"The paying customer is always right." |
Edited by - JubeePrince on 03/05/2010 07:34:27 |
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RodH45
USA
61 Posts |
Posted - 03/05/2010 : 18:32:01
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Electrical problems kick my a$%. Hate `em.
A few questions Ratchetknee.
Q. How long have you owned the bike? Are you 100% sure the wiring harness is the correct one. Over thirty nine years of service and with many possible owners there is absolutely no guarantee that any part is 100% correct. The fact that the headlamp wire fried may indicate significant wiring problem.
Q. I apologize in advance sir but are you 100% sure you have 12v bulbs and not 6v.
Q. When do the bulbs fail? After the bike is running; instantly, minutes, hours or a few days?
RodH '68 TR6R |
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tangerine-jack
USA
631 Posts |
Posted - 03/30/2010 : 19:37:40
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All hail Sir Lucas Lord of Darkness!
1: Check battery voltage with bike running at at least 1500 rpm- you should see about 13-14.5 volts. Any charging system can put out up to 18v AC, the rectifier changes this to DC voltage and the diode controls the amount of voltage going to the battery.
2: Without seeing your bike I can only assume the wiring to the rectifier is correct, if it is not you will get AC voltage bleed over which could cause blown lights. Check each lead coming from the alternator (there should be 3) and check that each lead has 6 volts output. The rectifier has a series of diodes in it that progressivly filter the AC voltage from the alternator into the DC voltage the bike can use. If the wires are wrong, you will have charging problems to be sure. If I remember correctly, all the wires are the same color at the rectifier, so that isn't much help but check the wiring diagram and that should put you on the right track.
3: Check the zener with a continuity test using an ohm meter. If you have a multimeter this will be easy, if not buy one since you will be using it a lot in the future anyway and they don't cost that much- good ones for home bike repair can be bought for about $20. The Zener should flow electricity in only ONE direction, not two. It should also not be shorted out, if I remember correctly it should show about 30 ohms of resistance. The end value is not important- the zener works by creating a resistance to the alternator and bleeding off excess voltage in the form of heat. If you get a very low resistance or no resistance at all, then the zener is toast. Since you've already replace this component a few times I don't think the zener is your problem but a symptom of it.
4: Check to ensure the zener is in a heat sink. On your 71 it should be mounted on the back of the intake box wich acts as it's own mounting bracket and combo heat sink. As mentioned the zener bleeds voltage away in the form of heat, if it's not mounted in a heat sink it will quickly die. At any given time the zener is trying to waste 4 or 5 volts- calculate the heat generated and you will see that this poor diode has a hell of a life.
5: Check the battery cells. Again use your multimeter and check the voltage in each cell of the battery. Put the black lead on the - lug of the battery and put the red lead into water in the cell closest to the - lead, you should be reading just over 2 volts. Go to the next cell with the red lead and you should read 4 volts. Etc etc for each cell and you should get +2 volts for each one until you get to the + lug at wich you should read 12v. Any cell not up to the task means the battery is kaput.
6: Now the fun part, take out all your bulbs, all of them, and retest the charging system. If it overvolts, then the problem is not the bulbs. If the problem goes away, then replace bulbs one at a time until the problem returns, this will show you if you have a bad bulb socket. The fact the main headlamp wire fried shows me that your main fuse is not installed correctly and you clearly have a huge draw on the electrical system in the lighting area. It won't hurt at all to install an inline fuse just for the headlamp, you are fortunate your bike didn't go up in flames.
6: Final option, and the most costly, is to convert to a Sparx solid state charging system. I had the same problem with headlamps burning out until I converted my bike over to Sparx. I think it's been about 5 years now and I've had zero, zilch, nada, null, negative ghost rider, problems with the charging system.
Phooey on the zener.
As a caveat to all this, ensure the wiring harness is in good condition and not shorted to frame or with cruddy connections. I assume you already did the obvious and ensured your charging lead is secure to the - side of the battery and the ground wire is to the +.
Words are so unnecessary!
   
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Edited by - tangerine-jack on 03/30/2010 19:42:26 |
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blowing bulbs
