DC Motor Direction Control

[willcavanagh]

Hi All,
I wonder if anyone can help me, I have a small craft machine I am trying to repair for my mum. I have found the problem, but have no way of working out the value of a faulty inductor.

It runs of 230VAC and has a direction control push to make switch, that breaks in the mid position. It has a DC motor in rated at 240VDC, a small circuit board has X 4 RL207 diodes, X 2 inductors, X 2 titanium caps, and a PTC.

2 of the diodes have gone short circuit, and the inductors have cooked and gone open circuit.

I can get replacement diodes and caps no problems, but I have no way to find out the value of the inductor, any ideas on what I can do?

The manufacture will not supply parts at all, and as it is out of warranty they will not do anything, it seems a shame to spend £150 on a new one for a few £'s worth of components.

Any help would be great.

Will

 

[ben123324]

it really depends on what kind of inductor it is. if it is a simple wire wound around some sort of core, then find the same gauge of wire, and rewind it with the same coil height that it previously was. if you are unlucky enough to have one of those component type inductors, try to read the value on it. there are many calculators to do this, similar to reading the codes on a resistor. dont worry though, most circuits take a range of similar inductances, so it doesnt matter if you are off target a little.

 

[willcavanagh]

Thank you. It is a wire wound what looks like a ferrite core, it is about the size of a 2W resistor, there are no markings on the inductor at all, as it was cooked when the diodes decided to go short circuit. The circuit is so basic, it would be a shame to loose out by one component, I have ordered replacement Diodes and Caps, as I am just going to replace all components.

 

[colin55]

Just put 50 turns of 0.5mm wire around an old ferrite rod from the aerial rod of an FM radio

 

[Ziddik]

i think increasing the turns of an inductor may not make that problems in a circuit. Have u tried to read the value of that inductor from pcb? It may have printed on the pcb just below the fried inductor.. Gud luck brotha..

 

[colin55]

i think increasing the turns of an inductor may not make that problems in a circuit.

Engwish is an accurate language. What you hav ritten is not understandabibble.

 

[ben7]

Likely the inductor is just a filter choke, so that will be easy to replace. Make sure when you put it back together that there is a properly sized fuse in circuit. It might help to use inrush current limiting too, most likely that is why the diodes failed.

-Ben

 

[alec_t]

I agree with ben7 that the inductor is probably just a choke, to suppress rf interference. Its value is unlikely to be critical, so if you can find some wire of a similar gauge to the fried stuff then you could wind it on the existing core. The number of turns won't be critical, but should be about the same as for the original winding (if you can make a reasonable guesstimate of that).
Alec