We test every single unit we make [we don’t do batch sampling] so we are confident that our controllers are working when they leave here. Over the years we have learnt that the majority of problems with new controllers are due to external wiring issues. That said, we do know that controllers can be easily broken, and that a certain amount of engineering expertise is required to use many of our products properly.

We hope you’ll never need this service page but if things do ever go wrong then here is what we can do to help;


FAQs and Knowledgebase

We have helped a lot of customers get their systems working. Everything we have learned from this is kept in our troubleshooting or knowledgebase sections. Please have a search around these areas first to see if the answer is there.


If you send us a description of the problem and ideally a photo or two we can often help you solve the problem via email.


All our controllers have a warranty against defective manufacturing for 12 months from the date of shipment. The warranty doesn’t cover damage caused by incorrect installation. Full details of our warranty process are here.

Repair Service

Here at 4QD we dislike the throw-away culture and like to keep our controllers going as long as possible, we have a lot that are over 20 years old and still earning their keep. But if yours does breakdown then we offer a fixed price repair service, full details are here.

But before you return something…….please read the manual carefully and double check your wiring, we do find that many of the controllers returned to us are not faulty.

One last point, we’ve also learnt that the majority of mosfet failures are due to suppression components not being fitted. If you haven’t already done this……you should.