| Author | Message | ||
     Rubberdown |
What do the "diodes" (2) on the fuse box do? XB9S 2003 | ||
| Jlnance |
Did you buy another bike? I think the diodes have to do with the safety switches. | ||
| Rubberdown |
It's U4's bike. Had to run a rescue mission late one night last week to pick him up after it would not start after he gassed it up on his way home from work.. No fuel pump when key is on. He got it fired up once since then but is not running again. | ||
| Easy_rider |
I have a '99 S3 service manual. There are two pages that conflict in terms of the schematic (pages 4-28 and 4-33 for those who want to check theirs), but for tubers the diodes are part of the clutch switch and neutral switch circuits. These do affect power to the fuel pump. Only 1 of the 2 need to be engaged. Did he fire it up in neutral and now can't fire in gear? If not, look at the bank angle sensor. Thinking back, I once crossed my brake and clutch connectors during reassembly (they 'parently aren't idiot-proof). I could only start in neutral or with my brake pulled in! I realize this is all tuber, but it should be a start until someone pipes in! | ||
| Ragnagwar |
A diode is used to keep the electric current going one way in a circuit. It will not allow the current a return path through the diode. | ||
| U4euh |
Thanks Rubberdown. DO these go bad, or blow, like a fuse does? If they allow current to travel one direction, and mine 'popped' I have a short somewhere right? I've got the airbox and seat apart looking for obviuos frayed wires, but nothing yet. One note to add, is the headlight fuse went out directly before this happened. | ||
| Jlnance |
U4 - Diodes can blow, and if they do, I would suspect a short. If you've got an ohmmeter, they are fairly easy to test. Fuses also tend to go out due to shorts. | ||
| Alreadyinuse |
For the purpose of troubleshooting, could you just replace the diode with a fuse? I haven't had a chance to look at the schematic to see why the hell they are using diodes.... If a diode carrys a lot of current, it can heat up and die from the heat over time -- it doesn't mean there's a short. I don't know how much current these diodes carry in this circuit, again I haven't had a chance to look at the schematic. | ||
| Alreadyinuse |
Oh yeah, and in case anyone is wondering, a diode only lets electricity flow one way through it... You can check a diode with a continutiy tester, but just because you have no continuity either way through the diode doesn't mean the diode is bad... Some diodes don't allow electricity to flow through them until they are presented with a high enough voltage, which a continuity tester does not do. You can use an ohm meter to test a diode... this is a much more reliable check of continuity for a diode... it totally depends on the specs of the diode... | ||
| Reepicheep |
For the record... silicon diodes will turn "on" with .6 volts forward bias. These are the vast majority of the diodes you will hit. Gallium Arsenide diodes will run .3 volts to turn on, but unless you are taking apart an old crystal radio I doubt you will find one. LED's, which are also diodes, sometimes take more then .6 volts, I am not sure why. Replacing the diode with a fuse to test the diode is akin to replacing your dog with a fish to test your dog.  | ||
| Jlnance |
LED's, which are also diodes, sometimes take more then .6 volts, I am not sure why. The forward voltage drop of a diode is a function of the materials the diode is made from. I dropped the semiconductor quantum mechanics class (seriously) so I can't explain the details. LEDs are not made from silicon, as it emits light in the infrared region of the spectrum. They are made from a variety of compound semiconductors, and each different compound will have a different voltage drop. As a bonus piece of information, Blue LEDs are made of silicon carbide, by Cree Research here in Durham, NC. | ||
| Reepicheep |
That makes perfect sense, thanks! | ||
| Henrik |
... and the Cree LEDs are set to be the next hot thing in flashlight "bulbs": http://candlepowerforums.com/vb/forumdisplay.php?f =45 ... many more threads like it abound. Henrik (not entirely tread drift ...  ) | ||
| Reepicheep |
I spent about an hour on that forum last night, dangit. Very interesting stuff. | ||
| Diablobrian |
It might be cool to substitute LEDs into the diode slots as a way to check if the diodes are good or not. If the LEDs (in proper orientation) light up and the bike runs it was the diode. If not then... Having a visual indication that the component is working is a good thing. Maybe something that Buell could consider for future bikes since diodes are hard for the rider to troubleshoot out on the road. | ||
| Henrik |
Did anyone say "Bill Bait" ...  It's fun to see how their tint, lux etc. discussions look very much like our oil, tire, contact patch, chain vs. belt etc. etc. discussions That said, it's pretty interesting how light output and run times has gone up since I bought my first Maglite. As an example look at the last output/runtime graph on this page, towards the bottom: http://www.flashlightreviews.com/reviews/maglite_m ag-led.htm Almost triple the runtime at almost double the light output for a 3D-cell Maglite. Well worth the $19 for the bulb to upgrade you old Maglites. Henrik | ||
| Bomber |
henrik -- is tread drift related to contact patches? I wasn't gonna, but you made me do it -- | ||
| Reepicheep |
Chomp! The max current through your typical diode is measured in amps (it only drops .6 volts, and power dissipation (heat) is volts times current, so even pumping a full amp through a diode is only .6 watts). LED's however, generally will blow with anything more then 50 to 150 mA. The systems could probably tolerate a decent voltage drop, so you could probably put three diodes in series and put one LED with a resistor in parallel with that, and create a "glowing tester". That being said, you can just slap a voltmeter across it and look for .6 volts as well when it is positively biased. (I'm still resisting the flashlight bait... but I can show you calculations from two years ago where I figured out that to build an LED headlight you were looking at about $4000 worth of LED's and some significant packaging challenges... though I bet it would be down to under half that much today). | ||
| Henrik |
is tread drift related to contact patches? It's gotta depend on the angular forces applied ...  Oh, and Bill, just buy a Petzl Tactikka XP and save $3940 .. Henrik |
