Dynamo question.

[-mini-]

My cars fitted with a dynamo, the red light on ignition goes off as normal in the daytime, indicating charging is ok, however when I put side or head lights on the red light will stay on when revved indicating it's not charging, any suggestions for what I can check?
Thanks.

[LDR209H]

Could be something as simple as a loose/slipping fanbelt. Also worn dynamo brushes or the voltage regulator is a. duff or b. needs adjusting are other possibilities.

[surfblue63]

Also check the electrical connections for the dynamo, voltage regulator, battery and engine earth strap for tightness and cleanliness.

[-mini-]

Thanks for help. I have checked the fan belt, have also checked the brushes which seem ok. How would I go about adjusting the regulator?
Thanks.