I have a 1965 MERC 900 - 90 hp and does not seem to be charging.
was told to test the DIODE STYLE RECTIFIER first.
Does this sound right, and how should I test it.

On 13 Jul 2006 16:52:15 -0700, "Bob.W" wrote:

I have a 1965 MERC 900 - 90 hp and does not seem to be charging.
was told to test the DIODE STYLE RECTIFIER first.
Does this sound right, and how should I test it.

It's worth a look. If you have an multi-meter/ohmmeter you can check
for open or shorted diodes. Good diodes only conduct in one polarity.
Assuming a full wave diode bridge (Clams, any one...?) it will have 4
terminals; 2 AC, +, and -.

Ohmmeter positive to either AC terminal and ohmmeter negative to the +
terminal should conduct.

Ohmmeter negative to either AC terminal and ohmmeter positive to the -
terminal should conduct.

Any other connection should not conduct.

Some multi-meters have a diode check setting that will measure the
voltage drop for conduction (~.6 -.7 V) and read "open" or full scale
for no conduction.

(fixed width font)

~AC o---+--||--+--o + DC
| |
+-)--||--+
| |
| +-||--+
| |
~AC o-+---||--+---o - DC

Just replace it... unless the stator wires are totally rotten and shorting -
it's GOT to be the rectifier.

-W

"Bob.W" wrote in message
oups.com...
I have a 1965 MERC 900 - 90 hp and does not seem to be charging.
was told to test the DIODE STYLE RECTIFIER first.
Does this sound right, and how should I test it.