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Mercury 20hp 1977 voltage regulator question

Evinrudemen

Evinrudemen

Regular Contributor
I am really not professional with Mercury engines so i need to ask one question related voltage regulator. I am going to buy boat-compass, which will have 12V lightning bulb with + and - connections. My Engine have the voltage regulator as seen in the photo. Does anyone know, which one connector is + and which one is - on my regulator? I am going to connect wire between regulator and compass, to get light work in compass, but i really not know, which is + and which is - connector on my regulator. Thank you so much for the help :)
Regulator.JPG
 
If that motor has a regulator then it must have a 12v starter/battery just connect the light to the battery; if it doesn't have a battery connected then the regulator will be damaged and inoperable.
 
This motor not have starter/battery. Just manual start, i really dream the starter, so hard to pull. This is Belgium made, and engine have the lighting stator and voltage regulator for driving light, if want use, i have never use any light because i only use boat during the daylight. Now i just become interested to get compass light working. Maybe i will buy separate small 12V battery, and wire the compass light from battery via switch.
 
Here's the wiring diagram for electric and manual start, the output seems to be AC which I assume is connected to running lights and any non DC device - I can't see it being used for battery charging. Do you have any lights connected to the output? you should be able to connect your compass light to the output, if you have a voltmeter connect it to the lighting harness and see what voltage is present.
I guess the regulator completes the circuit.
merc200-alternator.jpg
 
Thank you so much for the diagram :) No i have no any light connected to this. Seems like wires can be just connected to the output and no need worry positive or negative.
 
I haven't seen one of those is years....in order for the setup to work, you may need a filament bulb at the compass...if its based on an LED, it may not perform well (or survive) with the AC output...based on memory, the 'regulator' is just a clamping device, to limit the peak-peak value of the voltage from the stator
 
You wouldn't think it would need a voltage regulator at all since the charging amps would be very low anyway. It has to have a rectifier built in to the regulator to run DC items on the boat and charge the battery. You're not going to do that with AC voltage. I have a later model electric start 7.5 Merc with the lighting coil and all it has is rectifier fed from the two yellow leads. Hook your DVM to the yellow output leads and fire it up and see if it's charging DC volts.
 
I will check with multi-meter the situation when i have engine running, thank you for the help:) Often i really forget, that i really have the multi-meter, and it will tell me the answer about charging.
 
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