Moderator Airhead Posted March 31, 2010 Moderator Share Posted March 31, 2010 You want a picture of the rectifier under the tank? I checked it with my meter but not the lamp test. I guess i could try that also. I just got off the phone with Yamaha customer support, and they confirmed the bike is a 74 DT175 Yes a picture would be good, the rectifier as far as i know is quite small, no particular heat sink and a couple of flat blade connectors, like it is on my bike. Link to comment Share on other sites More sharing options...
BigBlkYJ Posted March 31, 2010 Author Share Posted March 31, 2010 Yes a picture would be good, the rectifier as far as i know is quite small, no particular heat sink and a couple of flat blade connectors, like it is on my bike. Ok, maybe these will help... The last one is of that diode connected in the bike. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 31, 2010 Moderator Share Posted March 31, 2010 Thanks, sure enough that is a rectifier, sorry I was expecting something bigger when you mentioned heat sink. well you may as well do the bulb test with that then. Next thing is there any sign of a resistor...bolted the the frames down tube? Also check your bulb voltages and wattages are correct, Link to comment Share on other sites More sharing options...
BigBlkYJ Posted March 31, 2010 Author Share Posted March 31, 2010 Thanks, sure enough that is a rectifier, sorry I was expecting something bigger when you mentioned heat sink. well you may as well do the bulb test with that then. Next thing is there any sign of a resistor...bolted the the frames down tube? Also check your bulb voltages and wattages are correct, I checked the rectifier also, checks good. The bulbs are all brand new (well they were last night, now they are junk) I'm going to pick up a battery for it right now, and we'll see if that helps. I'm not going to be doing any more tests with a new headlamp, as they are hard to find are sorta expensive to keep blowing up haha! Also, i have looked high and low, and there is no sign of a resistor. If there is one, i can't find it, and i'm not tearing the wire loom up to find it unless i know 110% there is one. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 31, 2010 Moderator Share Posted March 31, 2010 ok, i dont suppose i'll ever get to see this resistor it does get a mention in a Haynes manual though but not for your 175A...bolted to the frame down tube. If it is in the loom I would think there would be a fair old bump where it resides I would consider a regulator connected between the light switch feed (blue)and battery negative if it were me...an ac regulator that is. http://www.electrexworld.co.uk/rg06-regulator-1325-0.html Link to comment Share on other sites More sharing options...
Speedshop Posted March 31, 2010 Share Posted March 31, 2010 Right that resistor/diode with the green bands near the brake switch that cant be identified...... ......its what is known as an avalanche diode. Google it, but trust me thats what it is. It gives a very stable break down at a controlled voltage like a zener, so I'm guessing thats what is used to regulate the voltage. I think if you look at the wiring diagram there is one generator coil for lighting and one for running the battery and other lights? If thats right there won't be any control on the power for the headlamp, it'll be AC as well. Can you post the wiring diagram...I'll have a proper look at it? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 31, 2010 Moderator Share Posted March 31, 2010 You will notice it says A, B and C, It's probably a diagram for a later one and is in the mainn ok for yours' It is a Haynes after all but better than nothing. Link to comment Share on other sites More sharing options...
BigBlkYJ Posted April 1, 2010 Author Share Posted April 1, 2010 You will notice it says A, B and C, It's probably a diagram for a later one and is in the mainn ok for yours' It is a Haynes after all but better than nothing. Well at any rate THE BATTERY FIXED IT. Apparently you must have a battery in the circuit to help regulate voltage. The minute I put it in there the voltage dropped down to around 6.5vdc at idle and just under 8vdc with it screamin. Mind you this is on the dc stuff like the tail lights, blinkers and horn. I have yet to get a new headlamp to test, but I'm assuming this has fixed the problem with it also. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted April 1, 2010 Moderator Share Posted April 1, 2010 Well at any rate THE BATTERY FIXED IT. Apparently you must have a battery in the circuit to help regulate voltage. The minute I put it in there the voltage dropped down to around 6.5vdc at idle and just under 8vdc with it screamin. Mind you this is on the dc stuff like the tail lights, blinkers and horn. I have yet to get a new headlamp to test, but I'm assuming this has fixed the problem with it also. Rather than risk blowing a hard to find sealed beam, just connect any old 6v bulb in there first. Link to comment Share on other sites More sharing options...
Speedshop Posted April 1, 2010 Share Posted April 1, 2010 I suspect you still will have a fault as that diode is in the AC circuit for the lights, not the battery side. That is the voltage regulator shown next the the generator. Are there any numbers on the diode? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted April 1, 2010 Moderator Share Posted April 1, 2010 I suspect you still will have a fault as that diode is in the AC circuit for the lights, not the battery side. That is the voltage regulator shown next the the generator. Are there any numbers on the diode? The fact that it still functions as a diode as has been tested, has me thinking its just a bad connection issue...either where the diode connects to its leads, or where it connects to ground. Should be easy enough to check with a multimeter. Link to comment Share on other sites More sharing options...
Speedshop Posted April 1, 2010 Share Posted April 1, 2010 I have to buy these in boxes of 100 as the cost of one is tiny. But the ones i use have running voltages too high for what is needed here. They need to be matched to application. These can drift off spec so i'd change it to be sure. This type of diode is a little more complicated in its operation then a simple onewway valve. Link to comment Share on other sites More sharing options...
BigBlkYJ Posted April 1, 2010 Author Share Posted April 1, 2010 I have to buy these in boxes of 100 as the cost of one is tiny. But the ones i use have running voltages too high for what is needed here. They need to be matched to application. These can drift off spec so i'd change it to be sure. This type of diode is a little more complicated in its operation then a simple onewway valve. Well I'm going to play around with it this morning, I think what I'll do is plug my meter right into the lamp socket as before. This whole diode thing has me wondering why it's such a big secret, and not on any of the diagrams, or parts ordering pages. It's obviously a replaceable part since it's plugged into the harness and not hard-wired. As far as numbers on it, I didn't pull it completely out, for fear or damaging it to a point where it would not work at all, but I'm sure there are some on there. I've never seen and electrical component without them, and there doesn't appear to be enough colored banding to make sense of a value. Link to comment Share on other sites More sharing options...
BigBlkYJ Posted April 1, 2010 Author Share Posted April 1, 2010 No markings...What you see is what you get. Link to comment Share on other sites More sharing options...
BigBlkYJ Posted April 1, 2010 Author Share Posted April 1, 2010 OK, quick update. The diode wire changes color after it leaves the diode just past a connector by the brake pedal. The wire color changed to Black/white stripe. I followed it back to the run/stop switch. So basically it goes from the engine stator harness to the run/stop switch (at least from what I can tell) and its spliced once with a barrel connector in the headlamp assembly. I should also note, that with my meter connected to the headlamp, the voltage is still almost 14vac when revved up. So I think the problem is still there! :( Link to comment Share on other sites More sharing options...
Moderator Cynic Posted April 1, 2010 Moderator Share Posted April 1, 2010 OK, quick update. The diode wire changes color after it leaves the diode just past a connector by the brake pedal. The wire color changed to Black/white stripe. I followed it back to the run/stop switch. So basically it goes from the engine stator harness to the run/stop switch (at least from what I can tell) and its spliced once with a barrel connector in the headlamp assembly. I should also note, that with my meter connected to the headlamp, the voltage is still almost 14vac when revved up. So I think the problem is still there! :( And from the connector in the headlamp assy it will run to the ig sw. Sounds like its in there to work with the ig circuit then, maybe prevent sparking at the switch when it connects the coil feed to ground. There is a voltage regulator listed on the drawing, its a sealed metal unit 'that should be' under the tank mounted securely to the frame with a single yellow/white wire. You have proved the battery and the rectifier which will give a high voltage in the lighting circuit (by causing a low charging circuit voltage). The yellow white wire should come from the birds nest behind the headlight. The bit thats intreging me is when my regulator failed my lights STOPPED working unless i disconnected it, then it blew the bulbs out. Like chineese crackers pop,pop,pop Link to comment Share on other sites More sharing options...
BigBlkYJ Posted April 1, 2010 Author Share Posted April 1, 2010 And from the connector in the headlamp assy it will run to the ig sw. Sounds like its in there to work with the ig circuit then, maybe prevent sparking at the switch when it connects the coil feed to ground. There is a voltage regulator listed on the drawing, its a sealed metal unit 'that should be' under the tank mounted securely to the frame with a single yellow/white wire. You have proved the battery and the rectifier which will give a high voltage in the lighting circuit (by causing a low charging circuit voltage). The yellow white wire should come from the birds nest behind the headlight. The bit thats intreging me is when my regulator failed my lights STOPPED working unless i disconnected it, then it blew the bulbs out. Like chineese crackers pop,pop,pop Well i changed the front headlamp to a rigged up 6 volt lamp and also replaced the smaller meter lights, and the voltage seems to be better. I could not get over 8.5vac with all of them plugged in and working. Maybe you really do need everything hooked up and working for it to be correct...? I guess the battery must help regulate the AC somehow? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted April 1, 2010 Moderator Share Posted April 1, 2010 Well i changed the front headlamp to a rigged up 6 volt lamp and also replaced the smaller meter lights, and the voltage seems to be better. I could not get over 8.5vac with all of them plugged in and working. Maybe you really do need everything hooked up and working for it to be correct...? I guess the battery must help regulate the AC somehow? The lighting spec for a DT175A is 8.2v at 8000rpm. So maxing out at 8.5V sounds pretty good to me. It gives 6.9V +/-0.5 at 3000rpm too, how does that compare. Link to comment Share on other sites More sharing options...
BigBlkYJ Posted April 1, 2010 Author Share Posted April 1, 2010 The lighting spec for a DT175A is 8.2v at 8000rpm. So maxing out at 8.5V sounds pretty good to me. It gives 6.9V +/-0.5 at 3000rpm too, how does that compare. Well I'll have to see tomorrow they had to order my headlamp because I took the last one haha. The 6 volt lamp I'm testing with is only 17 watts also I'm assuming it will only get better with the correct 25 watt one in there. What seems so odd is that if any bulb blows, it could possibly take everything with it. (Whats funny is my manual actually says this in there after reading for a while, and also says that if a headlamp goes to try and idle it home basically) Link to comment Share on other sites More sharing options...
Moderator Cynic Posted April 2, 2010 Moderator Share Posted April 2, 2010 Well I'll have to see tomorrow they had to order my headlamp because I took the last one haha. The 6 volt lamp I'm testing with is only 17 watts also I'm assuming it will only get better with the correct 25 watt one in there. What seems so odd is that if any bulb blows, it could possibly take everything with it. (Whats funny is my manual actually says this in there after reading for a while, and also says that if a headlamp goes to try and idle it home basically) Can you not fit a later headlight from a 79, even if you have to fit the shell too surely thats better than these sealed beam units. You can buy the bulbs in packs of 5 i think and that way they aren't expensive. They are 35w too which should help keep the voltage in check. You are getting 8.5v with a 17w lamp so if 25 will bring it in on spec which we expect you should still be safe with 35w. Maybe it will take an extra half of one volt. But you will have a better headlight into the bargain. And spares will fit in your pocket. Have a look, surely that will be a straight sap with the sealed beam? Clicky Link to comment Share on other sites More sharing options...
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