1976 merc 1500 150hp

[jetwhine]

I did the tests for the rectifier per the service manual and according to the manual my rectifier fails test 1,2,3 and passed test 4. So I ordered a new one from merc and just recieved it. I tested it per the manual and it is backwards from the tests in the manual. Example: test 1 and 2 are backwards and tests 3 and 4 are backwards. So now the question is: is the manual just wrong or is the rectifier wrong. I know testing a diode is like a check valve it only allows current flow one way. So if the wrong lead set up, with the meter, causes an exact opposite, is the book wrong? Or did I get the wrong rectifier? It was orderd per my engine serial number and looks the same as the one that is on my motor now.

 

[Barnacle_Bill]

Re: 1976 merc 1500 150hp

Since we don't know exactly what you are doing here is how you test it.

Testing Merc?s square rectifier

If you use an analog meter set it on the RX1000 scale.

If using a digital meter, set it on the diode symbol.

1. Disconnect the battery leads.

2. Disconnect all wires on the rectifier.

3. Connect the red test lead to ground and the black lead alternately to terminals A and C.

The meter should show continuity.

4. Connect the black lead to gound and the red lead alternately to terminals A and C.

The meter should not show continuity.

5. Connect the black lead to terminal B and the red lead alternately to terminals A and C.

The meter should show continuity.

6. Connect the red lead to terminal B and the black lead alternately to terminals A and C.

The meter should not show continuity.

7. Replace the rectifier if you do not get correct readings.
View attachment 98458

 

[jetwhine]

Re: 1976 merc 1500 150hp

Ok so I took the book my analog meter and the new rectifier to my local boat shop and we did the test per the book as shown in the last post. In step 3 above in bhile's post it showed no continuity. In step 4 above it showed continuity. In step 5 it showed no continuity and in step 6 it showed continuity. So the conclusion is that the book must be wrong. What does anyone else think? And I did tell you exactly what I was doing, maybe you just did not understand.