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power dynamo problems

19 Feb 2020 01:40
Kh500
Mini Enduro
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power dynamo problems #1
hello everyone. When i push the starter button (1975 dt125) it just clicks. When it clicks, i get 12 volts to the lt. green wire. how do i test it, does it have to be off the bike? how do i test the armature? thank you, any help is needed.

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19 Feb 2020 01:53
RT325
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power dynamo problems #2
Hi & welcome from NZ. If ya feeling lucky its most likely just brushes worn out. If the solenoid clicks as you say then see if you have 12 volts on both sides of it--12 on the side heading down to the armature in which case i'd be into the brushes. Hope i'm right or it gets complicated & i hate complicated. One more unlikely thought is solenoids can fiz up internally & not bridge the contacts inside so will click & lift the terminal bridging bar thingy but corrosion stops it bridging across them. Thinking back to about mid "80's i had a red [maroon color] one of those & was a great little bike.

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20 Feb 2020 12:15
Kh500
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power dynamo problems #3
thanks for the imput, but the brushes are good. I did the continuity check from the positive brush to the plate which I say is negative and im getting continuity. I would think the positive brush should be isolated, but then again, its touching the armature and so are the negative brushes. so im asking, does the dynamo have to be off the bike to be tested and can the armature be tested?

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20 Feb 2020 13:36
RT325
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power dynamo problems #4
Out of my league really, but if the main field coil thingy was off [& be careful putting it on like pull the brushes back so the spring slides against their side-or do 'that' before removing the fields. Then with a multi meter test between each segment around the commutator & should be connected to each other all the way but nothing to earth or armature center etc. I suppose same with the fields if you can isolate them. Find each end of each field & have continuity but nothing to earth. Pretty bullet proof old system unless it's been [fixed by 'experts']. You've bridged the solenoid to send a good 12volts down to the stator?. One more thing--does it charge when running, red light go out etc, can hear the motor load a little as it cuts in usually. Sorry, reading back 12 at the light green wire, i'd have though starter would be red all the way to the stator fields, i'll go study [too old to learn].
Man i'm over electrics--i got given a derelict Eiger Quad but starter only worked by jumping [least of its worries] & spent days [of retirement] uncovering loom & using a needle to test at points all the way & finally bridged a relay but in the end found the switch at the left side park brake i was testing was the stop light [no stop light fitted] & the safety start switch was directly under the lever not visible & lever needed to be pulled almost right in to activate. I'm over it haha.

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20 Feb 2020 13:40 20 Feb 2020 14:02 by RT325.
RT325
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power dynamo problems #5
Not sure if anything relevant here. No red wire so i'm wrong sorry.
www.yamaha-enduros.com/index.php/forums/...ynamo-starter-wiring
Or maybe something in this link below.
www.dansmc.com/genstarter.htm
www.dansmc.com/yam_at2_electricstart.pdf
Looks like 'light Green' 'is' start circuit [be a heavy wire] after all that, so i 'guess' it comes from the start solenoid & then says Green from the Fields to the regulator so maybe medium heavy for charging. Thinking back to [when i was young] you could push the cutout in regulator & see the armature give a slick kick like it was trying to turn it into an electric motor but you wouldn't want to hold it there for more than a touch--although that's not the starter circuit just the charging side. Gettin sidetracked sorry.

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20 Feb 2020 13:58
MarkT
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power dynamo problems #6
Use the service manuals in the Tech Library. Yamaha has a good test procedure if you follow it.

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
The following user(s) Liked this Post 2fishkev, RT325, Snglsmkr

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21 Feb 2020 18:37
2fishkev
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power dynamo problems #7
+1 on MarkT ‘s advice. My first restoration was a Dt125a and by following the service manual and reading dansmc website, you can get her going. Check your grounds and have a well charged battery.

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21 Feb 2020 21:01
Makotosun
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power dynamo problems #8
The brushes may have continuity, but be worn down too far to work correctly. Yamaha still sells them, but they are quite expensive. There are some eBay sellers who have some for less - usually out of Singapore, but they work fine.

I had significant issues getting mine to work, and actually found the solution in the clymer manual - it had to do with undercutting the mics if I recall correctly.

IF it isn't one thing, it's another.

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22 Feb 2020 13:34
Kh500
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power dynamo problems #9
ok, I think I narrowed it down to the internal coils. Looking at the picture, from left to right, the bigger silver screw is the light green wire. the next screw is the big internal coil wire. the next is the orange wire. the next is the green wire which also has a small internal coil wire. the next is empty. the last one is the white wire which has alot going on. It has a bridge going to the positive brush and the big and small internal coil wires and then bridges over to the other positive brush. Now if you can follow all of that, heres the problem... the big internal coil wire has continuity to the plate, therfore grounding the positive brushes. Im thinking the internal coil windings are bad. what do you think? And does anyone have a power dynamo for sale?

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