Vaillant No Power / PCB Supply Failure

Boiler display is completely dead, no lights or response

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Blown internal fuse on PCB, No mains supply to boiler, Faulty main on/off switch, Failed main control PCB

Safety: Electrical work must be done with power isolated and by competent persons.

User checks:

Check that the boiler's fused spur or plug is switched on and the fuse is intact.
Verify that the household circuit breaker for the boiler has not tripped.

Professional checks:

Confirm mains voltage at the boiler terminals.
Check and replace internal fuses on the PCB if blown, after identifying the cause.
Replace the main PCB if it does not power up with correct supply.

Medium 3/5

Main Control PCB

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