Published 19 Mar 2024

Holman CO1605


Holman CO1605 overview

Timer data
TypeWater
ModelCO1605
ManufacturerHolman
Date2014

Operation

The timer electronics controls a small electric motor which pushes a pin either in or out, depending on which way it turns. This pin is part of a pilot-operated solenoid type valve that switches the water flow on or off. If the motor turns clockwise (with normal power polarity, ie +ve to red), the pin is withdrawn, a drain is opened which relieves pressure on the diaphragm and water flows. If the motor turns anticlockwise the pin is inserted, the pressure relief drain is closed, and water pressure pushes the diaphragm and stops water flow. The electric motor is performing the function of the solenoid in the following diagram and has the advantage that no continuous electric power is required to hold it either open or closed.

Operation of a solenoid valve
A- Input side, B- Diaphragm, C- Pressure chamber, D- Pressure relief drain, E- Solenoid, F- Output side 1).

The motor is geared down by a gear ratio of 11 to 37.

Components

Examples

This example is damaged, there is a little corrosion on the PCB and the LCD doesn't light up, although manual on/off control of the valve works.

Holman CO1605 top, inlet
Holman CO1605 sideHolman CO1605 frontHolman CO1605 sideHolman CO1605 back
Holman CO1605 bottom, outlet

Tear down

The whole thing is held together via three screws, two in the battery compartment and one hidden under the front panel label. The label can be pealed off to reveal the screw.

Holman CO1605 battery cover removedHolman CO1605 label removed

Holman CO1605 front panel and PCB extracted|

Holman CO1605 PCB board front with LCDHolman CO1605 PCB board front with LCD mountHolman CO1605 PCB board front
Holman CO1605 PCB board back

The water flow valve is operated by a geared motor that inserts or withdraws a pin that closes or opens a drain hole, that thereby depresses or releases the diaphragm that stops or releases water flow to the outlet.

Holman CO1605 gearboxHolman CO1605 motor bracket removedHolman CO1605 motor removed
Holman CO1605 gearbox removedHolman CO1605 valve cover
Holman CO1605 valve gear top
Holman CO1605 valve gear sideHolman CO1605 valve gear frontHolman CO1605 valve gear sideHolman CO1605 valve gear back
Holman CO1605 valve gear bottom
Holman CO1605 pin withdrawnHolman CO1605 pin insertedHolman CO1605 pressure relief drain
Holman CO1605 diaphragm in pressure chamberHolman CO1605 diaphragm removedHolman CO1605 valve chamber
Holman CO1605 motorHolman CO1605 motor frontHolman CO1605 motor rear

References and Additional Resources



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