79-83 Honda DOHC charging system help
The regulator/rectifier is a box that actually contains two separate devices.
The regulator is what sends the
power to the rotor. It turns on and off power to the rotor so the magnet turns on
and off so the system can maintain 14.4 volts at the battery. It senses the
system voltage on the black wire from the key switch. The black wire to the
rotor comes directly from the same black wire and is always on when the key is
on, it’s the ground potential white wire that is turned on and off by the
regulator circuit to turn the magnet on and off.
The rectifier is made of 6 diodes that take the 3 phase power from the stator
and rectify it into a single DC feed on the red/white wire that goes back to
the battery via the starter solenoid terminal. The rectifier has no internal
connection to the regulator, it's a separate device
and could even be replaced separately as a standalone piece by re-stuffing the
appropriate pins (3 yellow wires and the red/white wire) in the multi-pin
connectors
Prerequisites to taking charging
performance measurements:
IMPORTANT! Testing results will not be accurate and/or reliable without first verifying the following:
Make certain that your meter is
accurate. You don't need a super high dollar meter, but it does need to be
reliably accurate and have a good battery or batteries in it.
A minimum 14 Amp/Hour battery that is known for certain to be good,
has recently had a specific gravity test, a load test, and been fully charged
overnight. There isn't a charging system in the world that will charge a
battery that is no longer viable, so test the battery before you waste any more
time on fiddling with the charging system. We have had numerous people that
started messing with the charging system for days only to find out that their
battery was junk, so check it, even if it is "supposed to be good".
The Rotor should be verified to have between 3.6 Ω (ohms) and
5.2 Ω of resistance between the slip rings. This isn't always the end
of the road for rotor testing though, if it seems to be good and measure OK at
this point. It can still be failing when it's hot and spinning and running
because centrifugal force causes the windings to short together. We will be
able to test for this later, once we are ready to take some running voltage
measurements.
The Stator should have between 0.4 Ω and 0.5 Ω between any
pair of yellow wires and no continuity between any yellow wire and ground.
This is the least likely charging component to fail, but it does happen. The
continuity and short tests are usually definitive for these though. Some
rewound stators have been found to be higher in resistance, closer to 1 ohm
between any pair of yellows, and still work.
The Brushes should have carbon left beyond the end of life marks,
have good springs, and the brush leads from the connectors to the brushes
tested with the ohmmeter, and have less than 0.5 Ω resistance,
almost 0 Ω from the connector to the brush face. Wiggle and tug slightly
on these brush wires during this test to make sure they aren't flaky or
intermittent.
Connection Quality Is Extremely Critical To Charging Performance!!!:
Many charging problems on old
motorcycles can be traced to dirty, corroded, or burnt connections or the key
switch.
A loose, weak, or dirty connection or key switch can cause improper or erratic
charging system output. A melted plug is also a sign of a loose or dirty
connector. The heat comes from the resistance of completing the circuit through
oxide (or oil and dirt) on the surface of the terminals.
Check all the connectors. The battery cables and all the other wiring
connections should all be clean and tight. With pin and sleeve type
connections, where a blade inserts into socket, like in the multi pin
connectors, the pin, or blade, needs to fit into the socket very snugly to make
a good connection
Don't mistake the drag of the plastic shells when judging whether or not the
connectors are tight enough. They should kind of be a PITA and hard to put
together and separate from the friction of the actual connector pins in the
sockets. When you put them together then take them apart, you should be able to
see a clean shiny scrape mark on the metal pins left by the tight female
connector if you look there with magnification. We need bare hard metal to
metal contact, right through any dielectric grease or corrosion. The grease is
there to help stop corrosion, it's not there to be a conductor, and should not
be.
It's like trying to get a good 4 ohm measurement reading on the rotor, you have
to push like hell on the rings on a shiny place with the probes of your meter
to get the meter to settle down to the lowest reading it can. That's the
difference a tight connection makes, and what is necessary for really good
charging system performance where you need to pass significant power. You need
every connection to have less than 0.1 Ω of resistance ideally, because
they add up and make the voltage drop that you measure in steps 7 and 8, and
that is critical to good charging performance. There cannot be more than about
0.1 Volts of voltage drop on tests 7 and 8 or your charge isn't going to get to
the battery very well.
The Oregon Motorcycle Parts faq link at the bottom
of this post has some very good connector cleaning info with how to take them
apart and change pins and such linked in it.
Make sure that your connections are all clean and tight and not dropping
voltage before you try to troubleshoot the main charging components with
voltage and current meter readings.
If the connections are bad, troubleshooting to find faulty major components
will not produce accurate and reliable results, so preferably clean and tighten
them prior to taking meter testing results to send in to the forum for
analysis. You might even get lucky and have everything start working right just
from that cleaning and tightening of connections.
Do not let your motor sit running too long getting hot without adequate fan
cooling.
Testing Instructions:
Below are the charging system tests, with steps numbered 1-9 and some a,b,c,d part answers as well.
Perform these tests with the meter probes poking back side of the connectors or through the insulation, with all the
connectors
connected, running at 3000RPM unless it says otherwise for a particular step.
Make your own new Technical Help thread with the information you record
in it, see **Results Section below
Someone should answer your post and be better able to help you armed with
this data.
These are the instructions for each test. Put your answers in a list like the
one below the instructions in the Results Section.
The values in parenthesis are the "perfect world" values, probably
almost never exactly that.
1a. Check System Voltage - measure DC voltage at battery terminals w/
motor off key on (~12.5VDC)
1b. Check System Voltage - measure DC voltage at battery terminals @
idle (~12 VDC)
1c. Check System Voltage - measure DC voltage at battery terminals @
3000RPM (~14.4VDC)
1d. Check System Voltage - measure DC voltage at battery terminals @
5000RPM (~14.4VDC)
1e. Check System Voltage - measure DC voltage at battery terminals @
3000RPM with Regulator Bypassed *see 3d for bypassing the regulator explanation
and do this measurement at that time.
2. Check for rotor magnetism by dangling a .0015" feeler gauge by the side
of the alternator...(yes?)
3a. Rotor voltage - measure DC volts between black & white wire on Alt/Stator
connector (measure w/ motor off key on, should be
close to battery voltage)
3b. Rotor voltage - measure DC volts between black & white wire on
Alt/Stator connector varying DC voltage measure @ idle .
This voltage turns on and off as
the motor runs to regulate the output of the charging system by turning on and
off the
magnetism from the rotor as needed to keep the battery at 14.4 volts when
everything is working right. The meter reading won’t give a
complete
picture, as the on and off may happen frequently as the voltage regulation
threshold may be crossed frequently.
(Could be as much as battery voltage)
3c. Rotor voltage - measure DC volts between black and white wire on Alt/Stator connector
varying DC voltage* measure @ 3000RPM.
3d. Rotor voltage with Regulator Bypassed - measure DC volts between
black and white wire on Alt/Stator connector. @
idle
How to Bypass the Regulator - However, before bypassing the
regulator, make sure the field coil (rotor) isn't shorted. (You already did that,
right? )
Leave the alternator connector coupled, and insert an unwound large paper clip
into the connector at the WHITE wire location. Run a jumper wire from the paper
clip to the battery's NEGATIVE terminal. Now repeat the charge amps test, but
this time, DO NOT EXCEED 3000 RPM, the voltage could go dangerously high. Also
do not let it run long like this. - If the alternator starts charging, the
regulator is likely the problem. This effectively bypasses the regulator and
makes the charging system produce full unregulated output. If everything but
the regulator is working the voltage could go quite high, so don’t rev too
high, and don’t do it for long.
4. Stator voltage - measure AC volts between any yellow to any yellow wires on
Alt/Stator connector (~8 to 15 VAC)
5. Check rectifier - out measure DC volts - red/wht
wire to green wire on small r/r connector (≥14.4VDC same as battery)
6. Check regulator - reference/rotor supply - measure DC volts at black wire to
green wire on small r/r connector (14.4VDC)
7. Check r/r ground conductance quality - measure DC volts (voltage drop) -
green wire on small r/r connector to battery negative terminal (~0 VDC)
8. Check rectifier out feed conductance quality - measure DC volts (voltage
drop) - red/wht wire on small r/r connector to
battery positive terminal. (~0 VDC)
8a. Check sense wire (black wire) feed conductance quality -
measure DC volts (voltage drop) – black wire on small r/r connector to battery
positive terminal. (~0 VDC)
9. Also check DC amps into battery at fuse connector:
Charge Amps Test
Set up your multimeter for its highest current
scale, usually 10 amps.
Key off: Remove the bike's main fuse, and clip your meter’s leads in place of
the fuse.
Check polarity by turning the keyswitch on:
If an analog meter’s needle swings backward, that's good. If forward, reverse
the connections.
On a digital meter, you want a "–" (negative) sign.
Start and rev the engine to 3,000 rpm. Should read positive amps on meter; the
result should be at least one-fourth
of the battery's amp/hour rating which is usually at least 14 Amp/hours (so,
read over 3.5 amps).
**Results Section:
Copy and paste the list below into your own new Technical Help thread
and fill in your readings using the instructions above
Include a description and any other information you have regarding your charging system problem
1a. System VDC - @ motor off, key on _______________
1b. System VDC - @ idle __________________________
1c. System VDC - @ 3000RPM ______________________
1d. System VDC - @ 5000RPM ______________________
1e. System VDC Bypassed @ 3000 RPM _______________
2. Magnetism? ____________________________________
3a. Rotor VDC @ motor off, key on __________________
3b. Rotor VDC @ idle _____________________________
3c. Rotor VDC @3000 RPM _________________________
3d. Rotor VDC @ idle regulator bypassed______________
4. Stator VAC
____________________________________
5. Rectifier out VDC ______________________________
6. Regulator Black wire VDC _______________________
7. Regulator Ground wire VDC _____________________
8. Rectifier wire Voltage drop VDC _________________
8a. Sense wire Voltage drop VDC
___________________
9. Charging Amps DC ____________________________
Additional Information: __________________________
References and Notes:
Thanks to the following sources of information used in compiling this testing
procedure.
Familiarity with them is advisable before attempting to troubleshoot the
charging system.
Meter reading help:
Meter
help thread link
http://www.dummies.com/programming/electronics/measuring-stuff-with-a-multimeter/
Honda CB1000C Honda Shop Manual:
See
Chapter 18 Battery/Charging System of the CB1000C Honda Shop Manual. Click here
or right click to go there or download according to your browser.
It has a little more info than the 750 Shop Manual, and it's for the same
parts.
Rotor continuity test: 3.6 to 4.4 ohms was accurate for new rotors from Honda,
however rewound rotors will often
work fine at resistance up to 5.5 ohms and possibly even higher.
Mike Nixon's electrical troubleshooter article:
Link to Mike
Nixon's Charging Troubleshooting doc
2 Ω 120 Watt power resistor for Mike Nixon's Stator Test
http://www.mpja.com/prodinfo.asp?number=17786+RS
Oregon Motorcycle Parts troubleshooting faq:
Link to Oregon
Motorcycle Parts FAQ: