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Re: Switchboard Identifying help


This article does describe the 3 settings I have found on my switch being used on the A7 (last section). (but not the switch itself) I don't feel confident that my dynamo has been re-wound so I will stick with the two settings for now so I don't put the full 12V on the field windings.

http://www.da7c.co.uk/technical_torque_articles/threebrush_dynamo.htm

Location: Wiltshire

Re: Switchboard Identifying help

Hi Chris

As mentioned, until someone publishes a circuit, I am not familiar with the pre RP arrangement, and it is a pain to fathom from wiring diagrams.

At the risk of prolonging this, the direct links shown on the switch in Fig 1 of the article introduce confusion.
Whilst the article may have come out of A7CA mag, as far as I know it does not apply exactly to any Seven.

Digital meters do not work well in a car ignition environment, and they can get confused by erratic and noisy voltages.

Much depends on whether your system is operating as 3 or 2 brush.
Allowing for meter lead resistance, the resistance field terminal to 3rd brush (or earth if none) should indicate if wound for 12v or not. I measure at about 1.5 ohm for 2 pole models originally but others quote somewhat more.

From playing on the bench the field seems to tolerate considerable current without getting very hot; this may explain why many somewhat random 12v conversions survive. However in the car has a lot of other heat to contend with.

Location: Auckland, NZ