open.
4) If you do not already have a regulator connected, you may need to trace the wires to see exactly where they go.
5) If you are installing a new generator, or your existing one is in unknown condition, you should perform some simple
tests to verify that it is workable:
a) With an ohm-meter, you should measure resistance of ~ 2 ohms from terminal D to ground. If the resistance is
infinite, then either the wire from D to the generator is not connected, or the generator’s armature is open.
b) Similarly, you should measure resistance of ~ 5-6 ohms from terminal F to ground. Infinite resistance indicates the
wire from terminal F to the generator’s field coil is not connected, or the field coils are open. A low resistance (3
ohms or less) indicates partial shorting of the field coils to ground.
6) Attach the wires to the DR340, and mount the DR340 using the three stainless steel machine screws provided.
7) Reconnect the battery ground. If there is excessive sparking, there may be a wiring mistake.
8) If everything seems to be in order, start the engine and observe the ammeter and ignition warning light. If everything is
working correctly, the warning light should go out at around 900 RPM (depending on generator model). You should
also be able to see charging of the battery on the ammeter.
9) If there is no output from the generator, and it passed the above tests, see the troubleshooting section in the appendix.
10) Installing the cover. DR340 does not include the Lucas plastic cover. You can however, use your existing cover, or
find a used one. The base plate is laid out to accommodate a genuine Lucas cover. Two #8 machine screws are
provided to install it. Some aftermarket covers have different dimensions from the original Lucas covers.
Caution
Although the DR340 is protected against most everything that can go wrong, there are some things that can damage the
DR340 and/or your dynamo:
1) Connecting the battery backward. Be sure that you have the correct polarity regulator. If there is any doubt, check the
battery connections to see which battery terminal is connected to the vehicle’s chassis.
2) Reversing the D and B wires will create a direct path from the battery to the dynamo’s armature, which could damage
your dynamo.
3) B-circuit regulators: If the F wire is shorted to the D wire (dynamo armature), the dynamo will run at full output
without any voltage or current limiting. Lucas regulators and wiring are made so that you cannot connect the F wire to
the WL terminal (which is connected to the D terminal). We have copied this scheme, but if your wiring is not original,
it may be possible to accidentally connect the F wire to the WL terminal.
A-circuit regulators: If the F wire is shorted to ground, the dynamo will run at full output without any voltage or current
limiting. As a result, your dynamo and wiring could be damaged.
4) If the ground wire is not connected to the regulator, there will be no output from the dynamo. The regulator ground is
connected to the back plate, but in the normal installation, the back plate is insulated from the chassis ground by the
rubber mounting bushings. Therefore, the ground wire must be connected to the E terminal.
TESTING & CALIBRATION
The DR340 voltage and current limits are set at the factory, and normally, no adjustment or calibration is required. You may
however, wish to confirm that everything is working properly, or change the settings to accommodate your needs.
Both voltage and current limit are user adjustable, but within limits. For instance, changing from 12V to 6V will require
component changes. In the standard configuration, voltage limit is adjustable from 13 to 17V. and the current limit is
adjustable from 17A to 30A. Higher or lower settings will require component changes.
Adjustment to the voltage or current limit must be carried out on the car. For these adjustments, you will need an analog
moving-coil voltmeter (0-20V) and/or analog moving-coil ammeter (0-40A) plus a very small flat-blade screwdriver.
DR340 Instruction Manual Pg. 2
