removing light cover to change bulb

Good morning.
We have an Autosleeper Suffolk / Mercedes Sprinter.
We need to change a bulb in one of the ceiling lights.  (see photo)
We can't work out how to remove the circular white cover.  Have tried twisting it, but don't want to force it.
I can't find anything in the handbook.
Does anyone know how to do this?
Many thanks

Hi
Thanks for that.  I've looked, and can't see or feel any tabs.  Is it just the white cover that comes out?
I'm guessing it must be, if the switch is attached to the wiring.  I really can't see anything to insert a screwdriver into.

Thanks, Peter.  My husband has managed to remove it.  I see now what you mean by tabs.  They aren't visible from outside.  Now we know.  Thank you

Next question!!
Is any four pin 9w/840 bulb of the correct size and shape suitable, as it is run off the 12v system, or is there a special type of bulb, or is there some sort of transformer in the wiring?
Thanks in advance for the help.

Hi  

bonnie wrote:Is any four pin 9w/840 bulb of the correct size and shape suitable, as it is run off the 12v system, or is there a special type of bulb, or is there some sort of transformer in the wiring?

Fundamentally yes but just make sure that the base (layout of the pins) is the same.

No fluorescent lamp has a voltage associated with it. They all need a controller (for want of a better word) built into the fitting (mains or 12V) and it’s the controller that determines the working voltage.

If by any chance the new lamp doesn’t work it could well be the controller that’s faulty.

Brod

If you didn't notice the protrusions with the lamp cover mounts, you should look at them.

Before you buy a new tube check with another one from a working light. I had two in my toilet compartment. When I swapped tubes it was the same fitting that didn't work. It was the electronics that had failed, not the tube. Luckily, after an argument, Lumo replaced the whole unit with an LED version. 
It's also worth checking that the switch is working properly. After 10 years the switch on one of our lights is temperamental. And also check the 12V supply.

PLOUGHLIN wrote:Provided rated 12v, yes any should fit.

Here is the Lumo spec sheet for your Crown light.  http://lumo.eu.com/wp-content/uploads/2000-Series.pdf

Er... is that the correct link, please?  Seems to be for telecoms....

Cymro

Sorry: inadvertent duplicate post was here.

I'm glad this question was asked- the switch on the over-toilet light on our van is getting a bit hit and miss and I couldn't figure out how to remove the shade. I'm fairly sure ours is LED rather than tube or bulb.

I think you should pay attention to the bulb cover tabs if you haven't done so before. Any light bulb, car headlight and hand flashlight have protrusions on which the manufacturers attach a lamp cover. td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}

Guest wrote:I think you should pay attention to the bulb cover tabs if you haven't done so before. Any light bulb, car headlight and hand flashlight have protrusions on which the manufacturers attach a lamp cover.

This cover keeps the inside of the flashlight dry. The cover also protects the bulb from premature burnout from moisture.

sisiniaasthma wrote:

Guest wrote:I think you should pay attention to the bulb cover tabs if you haven't done so before. Any light bulb, car headlight and hand flashlight have protrusions on which the manufacturers attach a lamp cover.

This cover keeps the inside of the flashlight dry. The cover also protects the bulb from premature burnout from moisture.

Thank you for your valuable contribution to this thread. It would not have occurred to me that a mere cover could achieve so much.