Jump to content
Busdriver

Display cabinet lamp

Recommended Posts

Not strictly Tamiya but its electrical. I have 2 Ikea (other brands are available) lights that sit on the top of two sets of shelves. They are individually powered by a 12v transformer of their own. Both packed up within weeks of each other. I checked the bulbs and they were ok but it appeared that the transformers had fallen apart. Yes both of them. Not sure how.  Anyway i bought a generic 12v supply to see if this would fix the problem. Bingo connected up the first one a it lit up. Job done or so I thought!!. I then connected it to the other, nothing? Re checked the bulb all ok. I then diassembeled the cable from where the transformer was to the top of the cupboard. The cable had been joined in several places in order to make the cabling easier but all the joints were ok. Still no joy so I disconnected the light from all of the cable so there were just two short tails. Attached the transformer and Zippo. So transported to my model room upstairs to take the light apart and see if I could find the problem. Inside I found a small fuse so thought I'd cracked it, but alas the fuse was ok? Didnt have a 12v supply in my work room but I did have a 7.2v Tamiya (so it is tamiya related after all) battery. I stuck the tails into the sockets of the XT60 plug and low and behold it worked. Took it back downstairs and reconnected to transformer and, NOTHING. So diconnected the one that does work from the transformer and connected the battery and yes you guessed it it worked!! So I have one light fitting that works with both a 12v and 7.2v DC supply and another that is identical that only works with a 7.2v supply?

This is a picture of the light

IMG_2346.JPG.83bc3cde63e99b2c7a73a9653d916275.JPGIMG_2347.JPG.8522ff62d8c028eeb9870c57e1b4af2d.JPG

Any Ideas much appreciated!!!

Share this post


Link to post
Share on other sites

Do you think it might not be voltage but current limited? The transformer isn’t high enough amps for some reason? Second possibility the device is polarity sensitive and something in the one transformer is incorrectly polarised? I did a quick google and it does say some types of lamp without a diode bridge will not work unless the polarity is correct. Hopefully someone on here that is an electrical electronics expert will chip in.. I’m just speculating :) 

  • Thanks 1

Share this post


Link to post
Share on other sites

I don't think I made it quite clear but I am only trying to light one light with one transformer, so if it works with one lamp why not the other, knowing that both also run individually with7.2v. I did consider polarity and have tried both. It seems almost impossible?

Share this post


Link to post
Share on other sites

Ok, so the transformer works on lamp A but not B and the 7.2v battery works on A and B, and you have tried transformer on B with both polarity options and no light... so.. have you tried both bulbs (no housing) on the transformer? If so and it lights both there must be some electronics in the fitting that are reacting to either current or voltage levels, since the 7.2 v works would that point to over voltage? I’ll do a little googling on circuits that may be present in a DC device that aren’t in the transformer..

Share this post


Link to post
Share on other sites

Ok, I’ll have a last guess.. Could there be a thermally operated automatic circuit breaker in the transformer? Assuming there’s no manual switch, which could mean there is a mechanical defect in the housing, something making it draw more current, which is why the 7.2V battery works and the 12v doesn’t? No circuit breaker in the battery? So you might have to be stripping the fitting and looking for a short? Perhaps do some continuity checking of the wires and housing and switch assembly. I’m beginning to think this is the one... 

Share this post


Link to post
Share on other sites

I’ might have a test for this... Wire both the lamps to the one transformer, I’m thinking in parallel, which might prevent both lamps from working if there is a circuit breaker being triggered in the transformer by one...

  • Thanks 1

Share this post


Link to post
Share on other sites
9 hours ago, Lee76 said:

I’ might have a test for this... Wire both the lamps to the one transformer, I’m thinking in parallel, which might prevent both lamps from working if there is a circuit breaker being triggered in the transformer by one...

I’ll try this later

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...