Speed controller repair, what went wrong?

Replacing a mosfet with no success.

[@g7mks383]

Thanks Andy, thats keeps us going. Having a go and not just throwing away to landfill. Its my experience with these FETs and MOSFETs that you get an avalanche failure of components. Unless it was a complete overload. I always take the same approach. Nothing ventured nothing gained. Loverly dry day today off to cut my Woodland and meadow paths. Hopefully the brambles will not win.

[@TheInfoworks]

Martin, avalanche failure, it certainly seems like that's what happened. Nothing ventured nothing saved. Yes enjoy your woods and fight those brambles, cheers

[@TerryTerryTerry]

Good philosophy

[@TheInfoworks]

Cheers, keep on keeping on.

[@bootsowen]

It's tricky with the low end stuff like that Andy, the price of a single component, MOSFET or whatever, could be quite high compared to a new unit. I spent hours this week trying to figure out why my rainwater pressure pump kept cycling on and off, in the end I figured it out, learned a thing, got it working and have high pressure rainwater. Like you say, some aren't interested. as for FETs, there are NPN and PNP, every time I look at it I have to go back to the start, I recently have only dealt with TRIACs for AC so they are a slightly different beast. £400 on it's way to compensate us all for the hikes in energy prices! Those panels are nearly paid for!

[@TheInfoworks]

Owen, hope you did an analysis video, yes sometimes you can go down a rabbit hole if the item suffers multiple failures. Yes these are the times when previous energy investments are really paying off. I imagine your water pump was suffering with pressure loss to the diaphragm causing the hysteresis. Cheers

[@TheInfoworks]

@UC0RTtr15xEBVNM-Z38xGQDw Yes going no where near the rated value is something to recommend every time, even on quality gear, cheers

[@ianhelsbyservices]

I've just tested mine and can report the doublesided thermal tape is non-conductive (the stuff with the blue backing layer). So good for attaching the FET to the heat sink.

[@TheInfoworks]

Ian, yes as long as the clamp is insulated also. It's all rather disappointing and I suspect the listing specifications are different from reality, there's no label, I've sent it back for a full refund. cheers

[@bootsowen]

@@TheInfoworks The royal mail wins again!

[@TheInfoworks]

@@bootsowen exactly, but at least it's easy and free to return faulty junk. Should have know better really, cheers

[@covid19research86]

Great thanks from Kenya

[@TheInfoworks]

Good to hear from you, cheers

[@amazeallie924]

Thanks alot finally I got thanks.keep it up pl

[@nickrich56]

Off/on switch and a throttle. Bodge it!😊

[@TheInfoworks]

2 relays, piece of nichrome resistance wire and 2 micro switches will give 2 speeds, cheers

[@mehmetdemir5655]

Thanks for the video sir

[@TheInfoworks]

Theory with application makes the learning easier, cheers

[@Equiluxe1]

I would check to see if the aluminium case was in any way connected to the circuit board if it is isolated it would be better to connect the FET directly onto the case with a bit of thermal paste for good measure. But it looks like the driver for the FET is blown in any case. I have one of those cheap speed controllers floating around somewhere, I would not trust them above 12 volts and ten amps, The Chinese always claim more than they are capable off.

[@TheInfoworks]

Yes you are right, sometimes it's just not worth the effort with ultra cheap electronics. I thought about bolting the FET direct to the ali case but as it turned out all was pointless, cheers

[@Equiluxe1]

@@TheInfoworks I have just dug the one I have out, not taken it completely apart yet but the third item on the heat sink looks like it might be a Schottky diode, The unit I have looks identical other than the FET's have metal tabs and are isolated with heat transfer pads. There is no way that they can carry 60 amps as the tracks would blow at anything ove thirty amps. I will dig deeper on the one I have and find out what the FET's are and whether the third one is a double diode or another FET or transistor.

[@TheInfoworks]

@@Equiluxe1 That's grand, on this one it looks like a double diode. On the component data sheets it shows the need for a diode, cheers

[@paulrockwell2644]

Ya I having same problem ies

[@TheInfoworks]

Yes, Chinese junk, only good for very low voltage, cheers

[@juanantoniomorotecarrasco4464]

Na