A Our product warranty period is one year from the date of goods acceptance. if the broken parts can't repair, we can send the new products to replace the broken parts, but you need to pay the express cost by yourself. if after the warranty period, we can through negotiation for solving the problems, and we supply the technical support for the whole life of the equipment.

A

A For the double-coil and PWM control methods, the reverse electromotive force presented externally is very small, and the customer does not need to take additional measures. For the single-coil control method, the reverse electromotive force presented externally is large, and additional measures need to be taken. It is generally recommended to add a TVS tube (Adding a freewheeling diode is not recommended as it will slow down the disconnection speed and affect the electrical lifespan).

A It is normal. The epoxy glue consists of two parts: one is epoxy resin, and the other is a curing agent. The main component of the epoxy resin is alumina powder. In addition, the curing agent belongs to the amine category. The characteristic of amine curing agents is that they will discolor when exposed to air for a long time. This only occurs on the surface and does not affect the interior.

A It does not affect the performance. The surface of screw bolt is coated with silver. The main purpose is to maintain a small contact resistance in the contact area of screw bolt. Silver will discolor and oxidize when exposed in air for a long time. However, the contact area can still maintain a small contact resistance, which will not affect performance.