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TOPIC: AT1 charging help

AT1 charging help 16 May 2019 07:50 #1

  • Scottddove
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I posted this in the wrong place the first time I’m gonna try it here.

I really could use some help on this. I am trying to get this bike to charge. I have done all the testing procedures. I took my armature and stator to a shop that rebuilds starters and generators. He said my armature was no good. I purchased a whole new/different assembly off eBay that the seller said he would warranty if it didn’t work. Got it installed but it doesn’t appear to be any good either. I am just doubting I have 2 bad ones. I have new brushes, cleaned the armature real good, cleaned out all the little grooves, but it will only put out like 1.5 volts at 2000 rpm’s. I have the green wire off and grounded to the black wire the white wire taken loose and am testing for voltage on the terminal where the white wire would go. Am I missing something or do I just have two bad charging systems?
I have a limited time I can get a refund on the eBay purchase so I need some help quickly.
Thanks in advance. Captain Dave I need some of your wisdom.

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AT1 charging help 16 May 2019 07:52 #2

  • Scottddove
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I did take the new to me armature to a motor rebuild shop and they verified it was good.

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AT1 charging help 16 May 2019 11:12 #3

  • MarkT
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If you posted pictures of exactly how you hooked up your test connections it would help.

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1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250

AT1 charging help 16 May 2019 12:27 #4

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What you do to isolate the generator and test it separately from the regulator is completely disconnect the (A) and (F) wires from the generator... neither wire is connected to anything for the test... wrap them in tape .

Then you make up a jumper wire out of some spare wire and connect one end to the generator terminal F and the other end of your jumper wire to a good ground.

Start the engine and don't rev over 2,000 rpm. Use a voltmeter to see how much voltage you have at terminal A on the generator...

It's been a long time and I don't remember the wire colors on the AT that well... Using the picture Capt Dave posted a while back I've identified what I "think" are the wire terminals on the generator.

M = starter (goes to starter relay)
F = field wire for generator (goes to regulator)
A = Armature (goes to regulator)

I could be wrong so use this information at your own risk...

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1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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AT1 charging help 16 May 2019 15:40 #5

  • Capt.Dave
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The black wire is E or ground.
Capt Dave

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AT1 charging help 16 May 2019 18:23 #6

  • Scottddove
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Success I cleaned up all the connections and hit each brush with a grinder to deglaze them and it all works great. Ok I am going to document my experience to help the next guy. Things I have learned. You can take a 69-71 stator and armature and use it on a 1975 dt125, be sure to use the correct Governor/advance they are different. I could have changed the points to the other side of the points plated and accomplished this as well. The difference is the key way on the armatures are not the same they are 180 degrees off which will result in not being able to get the bike in time. If you pull your points and put them on the other side you could overcome this fact if you wanted to go that route. The test procedure in the book for testing the charging abilities of the unit without the alternator attached is confusing to me anyway. MarkT does a good job of explaining it above. The Commutator has to be round and clean and the grooves in between clean of debris to work correctly also. A machine called a “Growler” can be used to check the armature, a place that rebuild electric motors/alternators will have one. I hope this helps someone in the future. I was actually fixing this particular bike for a friend, I may have to actually get me a AT1 now that I have became well educated on how they work. For you guys that responded and tried to help I really do appreciate it. I started this hobby 3-4 years ago now and had no bikes at all. I now have 14 and my 15 year old son has 5 we are really enjoying working on these old Yamaha’s. I was intimidating by the AT1’s but not now. Thanks again guys.
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AT1 charging help 16 May 2019 20:43 #7

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Congratulations!

Yay2

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1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250

AT1 charging help 16 May 2019 20:53 #8

  • RT325
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Good one, she charges at last. Sounds like you & son are hooked like the rest of us!!.

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AT1 charging help 16 May 2019 22:14 #9

  • Midlife Motor
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You started this hobby 3-4 years ago with no bikes and now have over a dozen and 5 more for your boy? I gotta show this to my wife, you're making me look good with my six bikes in 4 years!

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It's better to remain silent and be considered a fool than to speak and remove all doubt.
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