UK Repairing Christmas light projector

[TheJay]

I disassembled a Christmas light projector to try and identify the cause of why the images from the projector weren't moving at all, when they used to. Looks like a couple of wires have come loose between the board and the motor wires.

I'm not sure which points they need to be soldered back on to. If I try the two empty contacts on the board, there isn't any movement in the motor. Other combinations cause one more more of the LEDs to lose power, so not sure what to do/what I am missing.

Could someone please help?

Many thanks.

 

[TheJay]

Thanks for your replies. I have tried testing on low volts and ohms and not getting a reading when spinning. On ohms it's reporting OL.

I've ordered two dc motors, just noticed they aren't expected to arrive until 5th June though...

 

[littlespark]

've ordered two dc motors, just noticed they aren't expected to arrive until 5th June though...

Still gives you over 6 months before you need to put them up for xmas

 

[TheJay]

See post #5
If the motor is jammed it will likely take more current which could cause the voltage across it to fall.
If it won't run on a 3V battery it's probably at fault. If you can get into the whole assembly you might stand a chance of finding what's wrong. It could be the reduction gears or the optical element they turn is stuck, or the motor itself, but in my limited experience the motor bit tends to be more reliable than the plastic/nylon gear trains they drive!

PS: Are you running the whole light projector off its original power supply?

I've got a couple of things to fix where the motor seems to be the problem.

I don't understand what could be broken in this assembly? Does the circular magnet wear down over time and need replacement? If so, where can I get one?

 

[Avo Mk8]

Magnet shouldn't be a problem.
The common failures are a break in the armature coil, or the 'brush' mechanism worn or not making contact. It looks like one of the contacts is bent up (ringed), shouldn't that contact spring be straight? Or has a bit broken off!
Those two contacts should press lightly (but not too lightly!) on each side of the commutator to provide current to the coils.
Use the ohmmeter to set it up.

 

[TheJay]

Here is a closer look at the one you have referred to:

This is the one from the projector light, there are black bits on the arms?

 

[Avo Mk8]

Well that's the problem.
One spring 'brush' contact on the Christmas light motor seems to have got bent, with one of the leaves pulled away in the wrong direction from the others (outlined red below). If that bent back piece was touching the same commutator segment as the other brush, it would explain why the motor didn't run, but had resistance.
Maybe the black is the remains of what were small carbon brush contacts, or it's some sort of grease?

I don't think there is much point in trying to restore it or fabricate a replacement given the motors are so cheap.
If there's enough of the springs left, you might get the motor to run by cleaning them up and bending them together, but I don't think it will last for more than a few minutes, or perhaps hours if you're lucky!

 

[TheJay]

Thanks for your reply, just as well I ordered some new ones base on what you said! Is there a way to determine the RPM and other identifying information on one of these from the internals when it's broken?

Different RPMs are going to change the speed of the projector lights, or in the case of a Furby, perhaps stop it functioning properly.

 

[Avo Mk8]

Different RPMs are going to change the speed of the projector lights, or in the case of a Furby, perhaps stop it functioning properly.

I believe the speed will largely depend on the voltage you run it at, and the load provided by the friction of what it's driving.
There is no specific rpm as such (eg servo control). Instructions might give a max speed, but you just need to supply a voltage that gives the correct speed of operation.

 

[TheJay]

Thanks for clarifying, that's good to know. It was educational opening them up.

 

[TheJay]

It's all going well, the motor works and the parts fit. I tried cleaning the round disc containing images of santa, snowman, holly and bells but now two of the images have been destroyed. Does anyone now how they are made/where to get supplies from?

It says "H46-005" and something in Chinese? "Just"?

 

[SJD]

No idea about the original wheel, but just wonder if you'd find a gobo wheel for a moving (stage) light of the right size?

 

[TheJay]

The images are 5mm each, I think the gobo wheels are a lot bigger.

Disc size is 46mm, central hole is 7mm and the mounting holes are 3mm. The distance from the edge of the internal hole to the centre of the images is 11mm.

I have ordered some printable acetate sheets for my laser printer, I can try and recreate them or perhaps add my own designs. I'd prefer a ready made option though, perhaps someone else has experience with this?

 

[TheJay]

These are the same images:

Can't be shipped to the UK from AliExpress :-(

Page Not Found - Aliexpress.com

 

[TheJay]

Here is my first design, I realised I can print onto clear acetate, so black areas will allow less light to come through and the lined areas will be transparent to allow the fullest effect.