testing stepper a motor

Hi all

I have a poorly printer and according to the manual the fault is a stepper motor or a sensor.

How do you go about testing a stepper motor? In idiots terms would be appreciated as I've no idea how to go about it.

I do have a multimeter

Pics of motor below

It is from a HP laser printer and the part is (after a quick search) a bit thin on the ground in the UK, but there seems to be quite a lot about in the USA. Which could end up being quite expensive with the shipping.

Thanks in advance for all reply's

regards

Paul

Frankly it's probably cheaper to buy a new printer! But I think that style of stepper (which is very old fashioned) is pretty well bulletproof. The only thing that can go wrong is a winding burning out or a a bearing going. If a winding has burned there will be a nasty smell and a bearing would be pretty obviously worn. If you could puzzle out the windings then an ohmmeter would check continuity. Modern printers have I think pretty well abandoned steppers and now use dc motors in a servo loop.

There was an HP printer that almost without fail broke a part when it was first switched on!

As Francis says there are centre taps to the windings, you should get a resistance reading from each of the 4 vertical pairs, and if all is well double the resistance on the pairs at the output on the left of the picture.

Emgee

Holding the motor in one hand whilst turning the axle, you should feel a distinct bumpy action as the coils pass the magnet. These motors make good generators so a multimeter on a low VDC setting should kick on both coils as the armature is turned.

But I agree with John and Frances - the motor is unlikely to be faulty. If you fancy a punt, they can be found on uk ebay today about £12.

More likely it's the sensor or board though. As inexpensive printers aren't meant to be repaired, usually cheaper to replace the printer unless it's something simple and obvious.

Dave

Hi Guys,

I must agree with the comments ! In nearly 50 years of doing electronic/electrical equipment repairs of one kind or another, I've never seen an electrically failed stepper motor ! Bearings, wear and seizing up, are the most common failure followed by the driving electronics. Ones that get electrically damaged are usually down to people playing about with them without understanding what they are doing.

usually cheaper to replace the printer unless it's something simple and obvious.

Most certainly the case if a relatively cheap domestic ink-jet, but this will be a bit more expensive (particularly if it is a colour printer), so possibly worthwhile?

Hi all

thank you for your reply's.

I' did test it and it was ok. re installed it and the gear train would turn with fingers (it wouldn't before).

Turned on the power and it did it's thing like they do and there was a bit of a clunk!!!!

same error code came up so I guess it is the sensor.

anyway To remove it I will have to take 3/4 of the printer in bits (I'm not going to do that)

I've spent all day on it and you have to draw the line somewhere.

So it's going on ebay, with the spare cartridges I have, as they are £100 a pop new.

thanks for all your help

regards

Paul