BigBlkYJ
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Posts posted by BigBlkYJ
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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)
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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?
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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!
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No markings...What you see is what you get.
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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.
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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.
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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.
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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.
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Any chance of a photo before you cover it up again?
so did you check this with your diode test too?
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
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Now youve got me wondering, there is no heat produced by a rectifier unless it is being used as a current shunt to ground, thereby acting as a regulator (a zenor diode) so is this the regulator then?
Well there's definitely no heat here, since the entire thing was cased in a poured rubber of sorts (i'm going to just shrink tube it back). I guess its working normal though since it functions. I'm still wondering if my not having a battery in place is causing this issue. However I'd hate to fry a brand new battery if it's not.
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That is without question a doide then, and furthermore a fully functioning one. I wonder about this resistor, i'm beginning to doubt it exists. That dido is in your case a rectifier, is there another more familiar one on that bike or is this the bike's rectifier?
this topic is bearing a lot of similarity to the other one on here at the moment(DT360)
No there is definitely a rectifier. Its mounted under the tank, and has an integrated heat-sink. What i found odd about that was the book said that the electricity should flow when connected from the pos. lead on my meter to the red lead on the rectifier. However its opposite. I would think though that this being from the factory would be correct. The leads are soldered onto it, not push on.
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The engine # is 443-010XXX (do you need the entire #?)
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166k is not going to reduce any voltage at all youre right. Acts as a diode though...lets prove that theory, hook it up in series with a light bulb across the battery terminals, then reverse it. if it is a diode and is working the bulb will light one way only,
Well i have a diode check on my meter and it only works in one direction with this thing. One way the forward voltage drop shows up as .53 volts. But just to be sure I did check it with a 6volt lamp, and it will only light in 1 direction.
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Hey thanks for the pic, i've been wondering what these look like. can you give me a more detailed description of where this resistor was connected to, I assume one side was to chassis or negative wire. And the other?
Measure the resistance of it to see what it comes out at...let us know.
The resistance was 166K ohms which seems pretty high to me. Also I don't know that this is actually a resistor. It acts like a diode when placed in diode check mode on a meter. Also its connected to the harness that comes out of the engine stator assembly's black wire (which has a double connector on the end, but only this is connected to it) The other end plugs into the harness that heads up into the main harness with the rear brake pedal switch.
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That is more than likely the issue. These bikes use a resistance in the ground/earth return line in the charging,lighting circuit. The resistance caps the voltage at a safe(ish) max of around 8 volts. If you check back that should lead back to the lighting circuit ac connections at the headlight.
Thing is it can fail, that will allow un capped voltage into the AC lighting circuit and when the lights are off depending on model and markets the same 13 odd volts into your battery. Destroying it in the process by boiling out the fluid.
If you post the first half of the frame/engine number we can narrow it down a bit.
When you say the first half, do you mean before the dash? Anyways, the manual i have for it, and the parts lookup online, both dont show a resistor anywhere that i can see. Also the wiring diagram doesn't show it..?
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Anyone know what this is? Is plugged into the harness down by the brake pedal. Its not listed on the schematic and i'm not sure if its what's causing the problem. Doesn't look like any resistor or diode i've ever seen.
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13 volts is about right, direct off the generator, don't forget you'll lose a fair bit at the rectifier then the voltage regalutor will control to a lower level.
If that was the level measured AFTER the rectifier and regulator then you do have a fault.
Well, this was measured at the headlamp connector. As far as a voltage regulator, i'm not sure there is one...? I know there is a rectifier, but i'm pretty sure there is no regulator.
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Hi BigBlkYJ,
The head, tail and instrument lights are on the AC circuit and the indicators, horn and stop lights are on the DC circuit.
As far as I know, a few things can give you too much voltage on the AC cicuit, blowing the bulbs.
Check all the connections and for any burned out bulbs in the AC circuit. It needs all the bulbs working to balance the voltage.
Could be the lighting coil resistance - I'm not too good on the detail on that one or the 175.
If AC bits are good then it could be in the charging circuit - If bad connections, or stuffed battery or rectifier, the voltage will then be too high in the lighting circuit.
I had the same problem which was fixed after a new battery and voltage recitifier. No problems since then (nearly 2 years now).
Hope that hels.
Gordo
Well that might be the problem right there then. There is no battery in it at all right now. When I got it, the battery was trashed completely, so I just figured that I'd test everything with a 6 volt battery charger. Everything works well with the charger there was just problems when I fire it up (without the charger on of course).
As far as the DC side goes: I can run the blinkers, tail light, brake light, horn, and the blinker indicator from the 6 volt dc charger. The headlamp, indicator for high beam, and for some reason the neutral safety light work on the AC.
Also the neutral light only seemed to work when the headlights were turned on, is this correct?
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No its AC, except for the electric start versions, and you don't need to rectify the headlight feed the bulb will be happy with AC or DC, just regulate it.
I dont mean to hijack your thread, but i'm currently having problems very similar to what you guys are talking about in here. I have the same year and make bike, however the voltage is too high when the engine is running. I get almost 13 volts AC from it. Its blowing all my lamps as well.
Everything works well with a 6 volt battery connected (well except for the headlamp and some of the indicator lights). There is a small black sealed capsule (possible the resistor you're talking about) in the engine harness. Could this be bad?
Also how would i go about wiring a external voltage regulator such as the one you posted above?
Thanks!
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I'm new to this whole vintage bike thing so go easy on me haha!
I've got an old 175 Enduro, which by looking online at all the parts look-up sites, says its a DT175A. Anyways, the stator is producing almost 13 volts when revved above idle, and its blowing all my lights. I'm wondering what the fix is for this, if any...? Its a 6 volt system.
Everything works well when a battery charger is connected to produce 6 volts to the battery terminals. The headlight is on the stator and will not work unless its running, which is unfortunate since its a sealed beam light, and sorta expensive to keep blowing up.
Any insight would be great, its pretty frustrating.
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1974 DT175a (I think) with high voltage from engine
in Dual Sport, Offroad Bikes
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I like that idea. I wonder if I can just find a conversion headlamp assembly that will accept cheaper bulbs but fit into the sealed beam shell. The sealed beam ones aren't too expensive. $10 each...