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Post by twitchytoes on Jun 5, 2018 21:48:20 GMT -5
Has anyone with a 139QMB had issues with the BA20d socket randomly losing connections? First I had it happen with the low beams, replaced the headlight and it worked for a while then it quit, so I played with the wires and socket and it works and has worked since. Now it's happening on my high beams. Did the same thing today and it worked for a quick ride around up until I turn on my road and they went out when I checked them one last time.
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Post by greginisn on Jun 5, 2018 22:10:13 GMT -5
With your voltmeter check for some 12VDC on the wires for Hi & Lo beam using a reliable ground. Then check for continuity, 0 ohms, from the connector that goes to the green wire and that reliable ground.
Good luck, Greg
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Post by benji on Jun 5, 2018 22:37:23 GMT -5
Actually, I'd check for AC voltage. Most scooters don't have DC headlights, but I separate lighting coil off the stator that provides AC voltage to the headlights and brake/tail lights.
If "playing with the connector" makes it work again, I'd check for corrosion. I'd also look at the high/low beam switch too.
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Post by FrankenMech on Jun 6, 2018 15:45:55 GMT -5
The AC headlight voltage is a myth The headlights run off shunt regulated 14VDC. There is just a lot of ripple on the line which causes some digital voltmeters to read it as AC. People believe their 'high tech' digital meters but meters lie if you don't know how to use them. Otherwise do check for corrosion and loose connections.
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Post by 90GTVert on Jun 6, 2018 19:05:28 GMT -5
The metal connectors that plug into the socket for + contacts get loose sometimes. May be able to fiddle with them to get a better fit if that's it.
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Post by snaker on Jun 7, 2018 11:05:25 GMT -5
The AC headlight voltage is a myth The headlights run off shunt regulated 14VDC. There is just a lot of ripple on the line which causes some digital voltmeters to read it as AC. People believe their 'high tech' digital meters but meters lie if you don't know how to use them. Otherwise do check for corrosion and loose connections. Have to disagree with you on that. There are wiring diagrams all over that show some/most scooters having the headlights and maybe other lights tapped directly off the stator AC output (typically the yellow wire on single phase, half wave systems). That wire also goes to the regulator to be regulated AC.
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Post by benji on Jun 7, 2018 11:08:32 GMT -5
Ok, I guess it's not 'true AC' cuz it doesn't completely invert voltage, but it's still alternating haha. And it does get pretty high some times, I've heard sometimes 20-30v but haven't verified that myself.
On my Honda Metropolitan, it had an intermittent headlight problem. The high/low beam switch had a corroded connection on the low beam side, and sometimes wouldn't have the low beam on especially if the voltage was low.
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Post by jackrides on Jun 7, 2018 13:47:24 GMT -5
The 2 wiring diagrams I have show a yellow from the middle of a stator coil split and go to the headlights and the rect/reg. The reg/rect could, I guess, shunt away some AC voltage -although not enough to lower the headlight voltage to a safe level with 2 35w bulbs, but how could it change it to DC? (Not fault finding, I'd really like to know.) Would someone please check this with an oscilloscope? And post a screenshot?
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Post by snaker on Jun 7, 2018 16:11:05 GMT -5
You can test pretty easy. Disconnect the wire (usually yellow) going to the regulator and fire up the machine. Two things will happen. You can put a meter on the yellow wire and read the raw AC output of the yellow wire which will vary with rpm. You will also being popping bulbs like zits. These AC light circuits will usually be on single phase/half wave systems. There will be a low output center tapped to ground circuit (usually yellow for AC lights) and a high output to ground circuit (usually white and sometimes pink for charging)
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Post by twitchytoes on Jun 7, 2018 22:38:26 GMT -5
I see. I haven't had time to mess with it any since last time I did. I seem to have my low beams working consistently but the high beams seem to not cut out if I just turn them on and idle, but it's not directly linked to throttle. I can sometimes ride for quite some time and they stay on, or sometimes the second I give it gas, it'll cut out. I have done some adjustments on the prongs before but it might need more. I might try that first, as moving the wires or even smacking the lens a bit makes it come back. I don't think it's voltage related, I think it's contact issues.
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Post by jackrides on Jun 8, 2018 0:44:45 GMT -5
A few contact tricks: Fingers and tools must be absolutely clean. Hot water, soap, then dry, Dry again. Hair dryer. Now wipe down all tool grips and contact points with alcohol, not rubbing - it has a skin additive. Wire contacts with alc., brush with fine steel wool or pen eraser and blow (compressed, not your pretty breath) clean. Reassemble with a little elec. contact 'grease'to prevent oxidation. (Most auto parts sell small packets of it for cheap.)
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Post by FrankenMech on Jun 8, 2018 23:12:05 GMT -5
snaker and jackrides, the stator would put out AC when disconnected from the regulator but the regulator shunts the negative portion to ground and the positive portion of the waveform over 14V to ground. The resulting waveform on the stator leads (yellow & white wires) is DC (the current flows mostly one direction) with a very high ripple that confuses most digital meters. A regular analog meter will show the DC voltage. A simple 1000uF capacitor will clean up the ripple and show the output as ~14VDC to a digital meter. A shunt regulator is not a rectifier. It just shorts out the waveform to leave a type of very messy square wave which is why the regulator gets so hot. The battery side of the regulator shows ~14VDC because the battery acts just like a giant capacitor. When I first encountered the wild 'AC' readings on scoots that people observed with digital meters I was lucky enough to have an analog meter along with the years of experience and knowledge to use the meters, read the schematics, and figure out what was going on. I had also encountered shunt regulation in many crude power supply circuits. I can understand why it would confuse a lot of people. People trust their 'high tech' digital meters when they really need to take anything they show with a large grain of salt. Experienced engineers and technicians know that. The little microprocessor in the meters can handle some DC and 50-60HZ AC with nice sinewaves but other frequencies and waveforms confuse them badly. Clean hands are important when handling connectors. I usually use disposable rubber gloves that are available for mechanics to wear. I also dip the bare copper wire in silicone dielectric grease before crimping the wire into connectors. I also fill the connector cavities with silicone dielectric before connecting them. The cheap connectors with inferior materials in them frequently do not provide long lasting gas-tight crimp connections. That is why I try to augment the crimped connection with silicone dielectric grease to help seal out oxygen and moisture. Silicone dielectric grease is available in about any size tube/packet/jar/bucket/container you might want depending on your usage. Automotive type electrical systems with nominal 12V batteries operate at about 14V (13.8-14.2VDC)to keep the battery charged. That 14VDC is also what keeps the regular incandescent bulbs burning brightly without unduly shortening the lifespan. When the regulators burn up the first indication is usually burnt out bulbs due to high voltage in the system which can be 'AC' after the regulator dies.
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Post by jackrides on Jun 9, 2018 0:22:45 GMT -5
Wow! Thank you Sir Frank!
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Post by GrumpyUnk on Jun 10, 2018 9:59:43 GMT -5
Interesting discussion. For the intermittent headlight, I'd check the 'flat connectors' inside the socket for how well they contact the bulb base. Odds are the metal base of the bulb has decent contact with the metal of the socket, but the two contacts on the base of the bulb are not in good contact with the flat metal contacts of the socket. Sometimes the metal can be 're-arced' to make better contact, and sometimes, replacing the socket is the only working solution.
Frank... Have you looked at the modification to the charging circuit that uses a full wave rectifier, and both the yellow and white outputs of the 'stator'? I got confused re half-wave and full-wave rectification, and the confusion has not gone away. Adding a dollar or so for a full wave diode array seems like a no brainer if it got more power to run the lights and keep the battery charged, especially if accessories were added such as USB charger or ??? Kohler single cylinder engines were fitted with a regulator/rectifier that got fed AC from the flywheel stator, and were solid, relatively inexpensive and as such were/are used on HD motorcycles as a non-OEM solution to a failed charging system. Any thoughts? tom
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Post by FrankenMech on Jun 10, 2018 13:56:15 GMT -5
Tom, I have looked at doing a full wave rectifier setup but it requires re-wiring the stator to lift the internal ground for the stator winding, -then it gets more complicated... I may have to look into that Kohler regulator setup though. Do you have any links to info on that regulator?
Some of the 125-150cc scoot engines use a three phase stator rectifier setup with a regulator also. Once I decided to upgrade my scoot to a 125-150cc engine I kind of lost interest in 50cc mods.
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