nighthawk 550 electrical problem


krusty kritter Wrote:
> jlpridge wrote:
> -
> From all that I ahve read so far I think it is the
> Rectifier. I wish I knew how to test it.-
>
> Maybe you're not clear on the concept of the rectifier regulator unit.
>
> There are two parts. The rectifier and the *voltage* regulator. They
> are both in the same unit.
>
> You test the voltage regulator operation by doing the "charging
> voltage
> test".
>
> You test the rectifier by doing the "diode test".
>
> Charging voltage test:
> With a fully charged battery installed, start the engine. The
> headlights must be on to load the alternator. Hook a voltmeter across
> the battery with the voltmeter on a 15 to 20 volt DC scale. As you rev
> up the engine, the
> voltage should rise from 12 volts to about 15 to 16 volts. Then the
> voltage should drop off sharply. Roll off the throttle and roll it
> back
>
> on and the voltage should rise and sharply fall each time you do this.
> The charging voltage test will prove that the voltage regulating
> circuit works.
>
> The diode test: This works best with an analog ohmmeter, as some
> digital meters won't read a diode correctly. With the ohmmeter on the
> R X 1 scale, check from each AC pin in the alternator input connector
> on the voltage regulator to the DC positive output pin. You should
> be
> able to tell the AC input connector from the DC output connector
> because it's probably impossible to hook the AC input conector to the
> DC output connector, the connectors should be "keyed" differently.
> To
> check the first three diodes, touch the black lead's probe to the AC
> input pin and the red lead to the DC output pin. If you don't get a
> reading, check with the black lead from the AC input pin to the DC
> output pin. You must get the SAME reading from each AC input pin to
> the DC output pin. It might be around 15 ohms, but I can't say for
> sure because the battery in an ohmmeter biases the diodes and causes
> different readings depending on the ohmmeter. If you don't get a
> reading, that probably indicates a blown out diode. Now, reverse the
> leads and check the other three diodes. Whatever lead gave you
> continuity from the AC input pin to the DC output pin is the wrong
> lead, so reverse the leads and check from the AC input pin to the DC
> negative ground pin. Again, you must get the same low reading from
> each AC input pin to the DC negative output. You should NOT get a
> reading in both directions, that indicates a shorted diode. You
> SHOULD
> get the SAME reading through all six diodes, going first from the AC
> input to the DC output to check the first three diodes, then
> reversing
> the leads and checking from the AC input to the DC negative side.

Thanks for the information. I have checked the voltage of the battery
when started and the voltage goes from 11.45 to 11.85 volts while you
rev the engine. The battery voltage before I put it in the bike is
12.85. It does not take long for it to drop below 12volts. My question
to you before I start attempting to test the diodes in the rectifier is
should I wait until my Clymer manual gets here later this week to look
at the schematics? I am really not sure which wire is what otherwise.
Also, while the bike is warming up it seems like the right bank of
cyclinders are missing until the bike is warmed up. By then you might
be able to ride for 15mins or so before the battery loses enough
voltage for the engine to shut off or run horribly. Going through some
of the Electrosport flow chart for troubleshooting the charging system
points to the problem of a loose ground. I have removed the tank and
checked the ground under there as well as the ground attached to the
engine crankcase. There is also a ground that bolts to the frame near
the battery and it is ok too. The flow chart said to jump a ground from
the neg terminal on the battery directly to the ground wire on the
rectifier and that does not seem to help. Also I have checked the
connections to the rectifier and they are tight and clean.


--
jlpridge
.

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