UK Repairing Christmas light projector

TheJay · Apr 6, 2024

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.

littlespark · Apr 7, 2024

Which ones have you tried?

I would expect these two…..

As they seem to be the only other ones that look “used” but that might be from where you have tried already.

Do you have a multimeter that you can use to measure voltage?

TheJay · Apr 7, 2024

Thanks for your reply, I do have a multimeter. What do I need to do?

The contacts you have circled are the ones I tried. I think the red wire may have been connected to the bottom contact as the end of that wire was missing and there was a bit within the solder. The problem was when I tried connecting the white wire to the other one, it stopped some of the LEDs working.

littlespark · Apr 7, 2024

Did you try it the other way around, or was there red remains in the solder?

Use the two prongs of the multimeter to measure between the two connections on the board. When the motor is supposed to run, there will be a voltage value present, and zero when not.

Set the multimeter one stage higher than the supply voltage of the device, and have it on DC Volts.

mainline · Apr 7, 2024

TheJay said:
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.
View attachment 115134 View attachment 115135 View attachment 115136
Could someone please help?

Many thanks.

Put the motor directly onto the batteries / power supply first to ensure that it's working.

TheJay · Apr 7, 2024

Thanks for confirming. As you can see, I am getting constant 3.2v on these contacts.

rQMVm9y - Upload the image directly to the thread.jpg

TheJay · Apr 7, 2024

This is the reading when the motor is added to the contacts. The motor doesn't move, originally it would move constantly. Also, you can see it turns the one LED off.

Avo Mk8 · Apr 7, 2024

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?

TheJay · Apr 7, 2024

Thanks for your reply. I removed the motor from the gear housing and it spins freely when I turn it, but when I use a 3v cell button battery it does nothing.

It looks like the motor from a CD/DVD but in my experience those don't usually have cables coming out of them, they connect using contacts on the base that aren't available on this one.

How would I track down the right one? Does it have a specific name? Do they come as standard with 7 holes in the top?

I was running the whole projector off it's original power supply.

TheJay · Apr 7, 2024

DC 1.5V 3V 5V 6V 6600RPM Micro RF-300C Motor Small Round?

westward10 · Apr 7, 2024

A button cell may not have the power to spin it. Try a couple of AAs in series.

TheJay · Apr 7, 2024

I had previously used a 9V battery on a similar motor and it worked, but it didn't work on this one.

westward10 · Apr 7, 2024

Set your meter to ohms and see if there is anything across the motor wires.

Avo Mk8 · Apr 8, 2024

Since the motor, when connected to the pcb, causes the led to dim, and the voltage on the terminals it connects to drops from 3.2V to 0.6V, the motor seems to have a low resistance (but not work!)
Another test could be to put the multimeter on a low dc volts range, spin the motor and see if any voltage is generated by it!
If it doesn't run on a battery looks like it'd died. Have you tried spinning it while on the battery?

There must be zillions of motors out there, finding a replacement could be a challenge.
If you are able to take the pinion off the motor shaft to put on the new motor, you will need the same shaft diameter and length on the new motor, and preferably at least one fixing hole to line up!

Avo Mk8 · Apr 8, 2024

TheJay said:
DC 1.5V 3V 5V 6V 6600RPM Micro RF-300C Motor Small Round?

That 300C reference looks useful.
Prompted by your post I had a quick look and they do look similar, eg:

Micro Motor 300 Solar DC 3V 4.5V 5V Motor For CD Player DIY Toy 2mm Brush Mo W02 | eBay

Lead length: 140 mm. Model: RF-300. Shaft length: 5 mm.

www.ebay.co.uk

If you have a pair of vernier callipers you could check the measurements of yours against the drawing dimensions in the link above.

They do look alike!

Good luck!

TheJay · Apr 13, 2024

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 · Apr 13, 2024

TheJay said:
'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 · Apr 14, 2024

Avo Mk8 said:
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 · Apr 14, 2024

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.