EPP Controls

The EPP controls fitted to Bomford machines vary only in the amount of on/ off services needed for each different model.

All control boxes have 2 proportional services that are controlled by a single lever joystick. These services are used for the lift and reach rams only. The remaining services being operated from rocker switches and will vary in number depending on the number of services on the machine.

Consider the points of the compass. The joystick functions are out of phase by 45 degrees. The lift & reach rams and the speeds at which they move, are dependant on how far and at what angle the joystick is moved i.e.; If the joystick is moved to 45 degrees then only one ram (lift or reach) will move at the speed determined by the position of the joystick. If the joystick is moved straight up & down or left to right then both the lift and reach rams will operate together in a direction, and at a speed determined by the position of the joystick. The speed at which both rams move together can be altered by biasing the joystick more towards one service than the other.

With practice both precise and parallel movements will come naturally and with far less effort than conventional cable operated systems.

The rocker switches on the control box operate the remaining services which are "Bang"-"Bang", or on/off spools that are NOT proportional.

Depending on the model, these switches being; cowl ram, head float, slew ram, and telescopic arm ram.

Other extra services may include, rotor on/off, arm float, power turn table, & slew lock out.

The EPPII control system has passed all the EMC (Electro Magnetic Compatibility) tests. This ensures that no stray radio waves wander off and interfere with other electrical components.

EPP Mk1 Boxes are rectangular and white in colour.

1) All controls will not operate .

a) Disconnect power lead from control box and test for voltage at power lead plug.

b) Power at plug - Go to 2.

c) No power at plug :- Check battery terminal connections.

d) :- Check terminal connections in plug.

e) :- Check fuse and replace if faulty with identical type (15 amp).

f) :- Check continuity of power lead to check for break in wire.

g) Replace power lead if found to have break in wire.

2) Power at power lead plug but all controls will not operate.

a) No controls :- Check terminal connections of control box power lead socket.

b) :- Remove control box lid (EPP Mk1) or control box base (EPP MkII), and check that the small amber lamp is lit when the power lead is connected and the main isolator switch is set to ON.

c) Lamp will not light - If the lamp is not lit then check the 2 fuses on the circuit board and replace as necessary with identical types.

Fuse FS1 = 15 amp

Fuse FS2 = 1 amp

d) Check operation of the main isolator switch & replace if necessary.

e) No controls - Fuses are found to be OK but lamp will not light - Check continuity of control box power lead for break in wire.

f) Replace power lead if found to have break in wire.

g) No controls - Check that there is power at the dump valve connections (Pink & Black wires).

h) Power at dump valve connections but valve will not operate - Remove solenoid and check operation (magnetises when power is applied).

i) Operation of solenoid is OK but dump valve will not work - Replace dump valve.

j) No power at dump valve connections - Check continuity of wires in loom.

k) Lamp lights but no controls - Carefully inspect the circuit board for signs of damage or burnt out tracks or components.

l) If damage is found replace circuit board.

3) Rocker switch services work but no controls from joystick work.

a) On MkII boxes make sure that the joystick terminal plug is plugged in.

b) Check the joystick terminal connections on PCBoard (EPP Mk1) or the terminal connections on the plug of EPP MkII.

c) Check proportional output at solenoid connections of wiring loom as follows;

The proportional signal wires to be checked are :-

Red/White & Red/Brown - 1st Ram.

Red/Black & Red/Blue - 2nd Ram.

Test the output from these wires one at a time as follows;

1) Remove a signal wire and connect an Ammeter capable of reading up to 5 Amps between the terminal pin on the solenoid and the removed wiring loom terminal.

2) Switch on the control box and move the joystick to the corresponding position for that ram movement.

3) The readings should be:-

a) 0.7 Amps when the joystick is at its minimum movement and the relays are first actuated, - and 2.7 Amps when the joystick is moved to its full extent.

b) Repeat this test for the 3 remaining signal wires and note the outputs.

c) Replace joystick if there is no output.

e) Check the circuit board for signs of damage and replace if necessary.

4) Rocker switch service(s) will not work.

a) Remove the 2 wires (one coloured & one black) from the solenoid which normally operates the service and connect a Volt Meter to the 2 terminals.

b) Switch on the control box operate the switch and check the voltage, it should read approx. 12 volts.

c) Check operation & continuity of rocker switch and replace if necessary.

d) Check the continuity of the wiring loom and replace the loom if necessary.

e) Check the circuit board for signs of damage and replace if necessary.

In the event of a service not working, or complete electrical failure, it is possible to move the arms by manually activating the solenoid valves. This is done by simultaneously pushing in the rubber caps on the end of the dump valve ( the only single ended solenoid valve) and the relevant spool valve. Pushing the dump valve spool will cut the flow off from the tank and cause the system to charge with pressure allowing the rams to move when the associated spool is depressed. Pressing the spool valve on it’s own will not work as the dump valve will be open, and the flow of oil will go straight to tank.

We can carry out electric control box refurbishment and repairs including, switch, joystick and PCB replacements.

We can repair PCB’s or supply and fit exchange item’s where down time is sensitive.

All units are fully tested and carry a 6 month warranty on all replaced/repaired parts.