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Control board Control board

Summary

  • Failure mode Failure of circuit boards or switch contacts can lead to machine failure.
  • Durability feature Good design of components/PCBs and inspection/testing.
  • Cost

Good practices

  • Good practicesCompliance with test standards
  • Good practicesPower surge protection
  • Good practicesSoldered joints/connectors where this does not inhibit repair
  • Good practicesPCBs protected from water ingress
  • Good practicesSurface mount components where possible
  • Good practicesDocumented PCB inspection/test
  • Good practicesSwitch and dial testing

Bad practices

  • Bad practicesNo testing of PCBs/connections/ switches
  • Bad practicesNo power surge protection
  • Bad practicesSpade connectors used
  • Bad practicesNo surface mount components
  • Bad practicesInadequate water ingress protection
  • Bad practicesNo PCB inspection / test
  • Bad practicesNo switch and dial testing

Key facts

  • Around 40% of washing machines purchased in 2012 were to replace a product under 6 years old.
  • 80% of customers want guarantees of 2 years or longer on major appliances.
  • Design reviews identified cost savings of £550k per 100,000 units could be achieved.
  • Consumer research indicates reliability as the most important product attribute for washing machines.

Icon key

  • Failure mode Failure mode
  • Durability features Durability features
  • Cost saving Cost saving
  • Low cost Low cost
  • Cost neutral Cost neutral
  • High cost High cost

Specification for improved performance

The specification below provides the recommended improvements needed to improve product durability. They are ranked from bronze to gold based on the effectiveness of the change in improving durability, with bronze being the minimum and gold being the maximum.

Replaceable PCBs; vibration, heat and water (IP66) protection; dials and switches specified to last at least 1,300 selections

  • Control and power PCBs and interface units/switches to be easily accessible to remove and replace by service technician requiring no special tools or equipment.
  • Replacement PCBs, whole interface unit or dials and switches to be readily available in the UK for at least 5 years after the machine is last manufactured and at reasonable cost (less than 20% of the latest cost price of the new machine).
  • PCBs to available pre-programmed or are able to be configured from the board itself without specialist equipment. Any reprogramming software to be made freely and publically available to the repair sector.  
  • Soldered connectors to be used on PCBs where this does not hinder repairs. Clip in connectors to be used rather than spade types on other connections.
  • All PCBs and connectors to have vibration protection (e.g. rubber mounts) and acrylic or silicone conformal coatings.
  • All PCBs and connectors to be placed so as to avoid any potential water leak risk and should be protected from water/humidity ingress to IP66 standard.
  • Critical components on PCBs to be well spaced with adequate heat sinks.
  • Power surge protection to be provided on the power board (e.g. using a varistor).
  • Wiring/looms not to be under tension and to be well supported.
  • Switches and dials to be specified to last at least 1,300 selections * 

Surface mount technology; self-diagnostic fault codes; PCB inspection; gold plated connectors; specified for 1,800 selections

  • The machine should indicate a self-diagnostic fault code on the display. Any fault codes to be made freely and publically available to the repair sector. 
  • PCB components to be surface mount technology where possible.
  • PCBs should comply with IPC610E and IPC-J-STD-001 on PCB manufacture.
  • Where electrical connections are not soldered, gold-plated connectors to be used rather than tin-plated.
  • Switches and dials to be specified to last at least 1,800 selections  

Dials and switches specified for 2,300 selections; environmental testing

  • Switches and dials to be electronic / contactless types
  • Chips/integrated circuits (ICs) to be connected via a ZIF (zero insertion force) connector 
  • Switches and dials to be specified to last at least 2,300 selections
  • PCBs to be tested using environmental test methods **

Testing to demonstrate performance

Examine and operate buttons, switches and dials to try to identify any potential issues such as weakness, looseness, stiffness etc.  

Ask for clear evidence of the requirements listed above, e.g.: technical specifications, drawings, photographs; test data (ideally from an independent test house), quality control data.

* Switches, dials and buttons in 10 randomly selected production machines to be tested, for each position available (e.g. on a dial), without failure in 100% of cases. Details of the actual test method is to be provided.

Power / on-off button are to meet household appliance safety standard EN60335-1 which requires switches to operate for more than 10,000 cycles. 

** Environmental test standards:

  • EN 60068-2-6:2008 (environmental testing Part 2-6:  Test Fc: Vibration (sinusoidal)) and EN 60068-2-64 (environmental testing Part 2-64: Test Fh: Vibration, broadband random) for vibration resistance for circuit boards.
  • EN 60512-6-4 Connectors for Electronic Equipment - Tests and Measurements - Part 6-4: Dynamic Stress Test 6d: Vibration (Sinusoidal) for connector quality.

Cost implications

Improved reliability of components can reduce early returns and improve brand reputation which, in turn, can lower business costs and increase long-term sales.

To calculate overall cost savings for your business, use the WRAP cost/benefit analysis tool (currently in draft form and available on request).

Saving

Neutral

Clip in connectors
Clip in connectors are common in PCB technology and so should be neutral to very low cost.

Water and humidity protection

PCBs should already be water ingress protected to IP66 for safety reasons.

Gold-plated connectors
As only small  amounts of gold on connectors is required, it is expected that this will add only tens of pence per PCB.  

Low cost

Water and humidity protection – encapsulation

Full encapsulation or waterproofing of PCBs would add a greater cost but should not be necessary if PCBs are carefully placed to avoid any damage from joint leaks.

Power surge protection

Surge protectors are commonly available and the additional cost should be low.

Surface mount technology

The use of surface mounted components could add a significant cost depending on the volumes made and production techniques available in the factory of choice.  

PCB/switch testing and inspection  

Any testing and inspection will add cost in terms of rig time and labour costs.

Zero Insertion Force connectors 

ZIFs are a little more expensive than regular pin connector blocks  

High cost

Contactless switches 

Some contactless switches, whilst very reliable, can add significant cost.