Knowledgebase Contact Us


We test every single unit we sell 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.

If your controller is not working please follow these steps:

  1. Check our troubleshooting page, this has fault finding sheets for each model, please print out and complete the one for your controller.
  2. If this does not help to resolve the problem please contact us by email or phone with the fault finding results.
  3. If the problem still cannot be resolved, then please return the controller to us for testing/repair as detailed below. Please make sure you complete and enclose this returns form. Please send to our head office address: 4QD Ltd, 36 Greenfields, Earith, Cambridgeshire, PE28 3QH.

Returns Form


You may also find it helpful to check our knowledgebase sections for solutions to problems with particular applications/set-ups.


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 we aim 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.

Range Test Minor repair [e.g. fuse tracks] Major repair [e.g. mosfets or relays]
4QD Range £30 £45 £60/£90 [ top/bottom board]
PRO-120/150 Range £24 £39 £60 [not Pro-120*]
PRO-160 £24 £39 £60
PRO-360 £24 £45 £60/£90 [ top/bottom board]
DNO Range (5/10) £24 £30/£36 £45/£51
VTX Range £24 £36  Not available*
Porter Range/SST £24 £30 £36
Accessories £12 £24 n/a
  • All prices quoted here are in UK Pounds, and include VAT. They do not include return carriage which depends on location.
  • If your controller requires a major repair we will contact you for approval before we carry out the work.
  • We only charge for testing if we can’t find any problem with the controller.

If you need to return a controller to us please download and complete this returns form, this will give us the information we need, and it has our address on it.

Before we raise your hopes too high we should tell you that not all controllers can be repaired. We’ll do our best as we hate to see them scrapped but sometimes the damage is too extensive, and sometimes the smaller tracks on the board can get damaged when removing the relays and mosfets.

We try our best to hold parts for older controllers, but it is not always possible. If a controller is over 5 years old  it may not be possible to repair it but we’re happy to take a look. We are unlikely to be able to repair controllers that are over 10 years old.

We aim to process out of warranty repairs within 14 days of receipt, although at busy times it may be longer than this.

When the controller is ready to be returned, we will email you an invoice with a link to our secure debit/credit card payment facility, or we can take your payment over the phone.

Customs warning for customers outside the UK

To avoid import duty being charged by UK customs, it is very important to mark the parcel and returns form with “Faulty equipment of UK manufacture, for repair. No commercial value”

You may need to fill in a customs form: declare the goods truthfully e.g. Motor speed controller. If you have to declare a value put a nominal value [£10]  as the goods are faulty.

If you don’t do this then the UK customs may add on a heavy charge which we will have to pay and charge back to you.

Some countries may also have customs ‘temporary export’ forms, filling one of these in should speed the incoming customs clearance of the equipment when it is returned to you.

Notes: * We have found that major repairs on the Pro-120s and VTXs are quite likely to result in damage to the small tracks around these components, this can make them unreliable so it is not advisable.