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75 r90/6 not charging

Armand
Posts: 81
Joined: Mon Jan 11, 2021 6:53 pm
Location: Binghamton ny

75 r90/6 not charging

Post by Armand »

Gentlemen, among many other things the bike is not charging. I’ve put in a new diode board, voltage regulator (2) and new battery . . I measured the resistance on the slip rings and got 4.0. .I see varying acceptable ranges depending on the source YouTube 6.21-7.59,Clymer 3.4-3.74, factory manual 6.9. Maybe I’m reading it all wrong. But, if I’m correct, what does it mean? If it were infinite , the wire is broken somewhere. But 4.0 indicates resistance. Some of the books are too far advanced for me.

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schrader7032
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Re: 75 r90/6 not charging

Post by schrader7032 »

If you got the right rotor, the rotor testing should show around 3.4 ohms. The 6.9 number is for the early alternators.

With all the new components replaced, it would appear that something was installed incorrectly or a part has failed. Who supplied the components. Do they offer any troubleshooting tips? Snowbum has a troubleshooting section on his website.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

Armand
Posts: 81
Joined: Mon Jan 11, 2021 6:53 pm
Location: Binghamton ny

Re: 75 r90/6 not charging

Post by Armand »

It’s the original rotor . So 4.0 is not usable? I’m slowly working through wiring gremlins. I suppose it could be anything. The bike runs great but only for about 1.5 hours( new electronic iggy). Thx for the input, I’m going out to plug away some more. I have been using snowbum also

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schrader7032
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Re: 75 r90/6 not charging

Post by schrader7032 »

I don't think a 4.0 is that far out, so I think it's usable. I'd check elsewhere.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

Armand
Posts: 81
Joined: Mon Jan 11, 2021 6:53 pm
Location: Binghamton ny

Re: 75 r90/6 not charging

Post by Armand »

Actually, I just retested the slip ring resistance. I came out w 3.9. I then noticed that my meter zeros at .2. I can do simple math so maybe 3.7 is accurate which is better. Onward through the fog!

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srankin
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Re: 75 r90/6 not charging

Post by srankin »

A quick test is to jumper the black and blue wires at the voltage regulator plug. If you do and at 1500rpm the red light goes out and charging starts you have a bad regulator. if the light stays on, it is in the alternator diode board.

By the way, I just had a charging issue on my R80RT, turned out to be one of the brush terminals in the front of the alternator had come loose. I passed a continuity test but when I wiggled it, it failed. So like Kurt says, recheck your connections. Good luck, St.
Owner of a 84, R80RT and 78, R100RS

Armand
Posts: 81
Joined: Mon Jan 11, 2021 6:53 pm
Location: Binghamton ny

Re: 75 r90/6 not charging

Post by Armand »

I just rechecked things. It seems to be charging. I had the meter on the battery and watched it rise to 13.5 . I stopped then. But now the gen light stays on and dims as the rpm rises.
Having sip f espresso now , then back at it. I’ll have it running good by winter.
Thx for the input.

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srankin
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Re: 75 r90/6 not charging

Post by srankin »

If you have a Katdash LED system installed into the idiot lights, you may get a very dim red light. If it is the stock bulb, Snowbum covers the issue in his works, lol, good luck finding it. If I recall, it could be a weak but not totally failed diode in the board.

13.5 charge is good at the battery. LOL, you may not have a problem at all. St.
Owner of a 84, R80RT and 78, R100RS

Armand
Posts: 81
Joined: Mon Jan 11, 2021 6:53 pm
Location: Binghamton ny

Re: 75 r90/6 not charging

Post by Armand »

Success I think. I checked jiggled all the wires. The voltage now goes up to 14.5 and stops there AND the gen light goes out! Must have fixed itself…..thanks for the input. Now for a cold ride.

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srankin
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Re: 75 r90/6 not charging

Post by srankin »

Check the end connections of the wires you jiggled to get things working. LOL, that is how I found the loose terminal causing my problem.

Cold ride, get heated gear, it is great! Have a good ride! St.
Owner of a 84, R80RT and 78, R100RS

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