My central light fitting has 12 small (diode?) bulbs. For the last few weeks it flickers,dims and then goes off after 5-10 mins. It has a KAOYI KTB-150 transformer.
Could this be the source of the problem? I can't see any signs of damage or overheating on it but don't know how to test it.

Peter B, November 2010

What a handy site this is?
Have to agree with Paul there.
I had major problems sourcing a 60 watt Kaoyi sliding foot dimmer.
I came across the same company as somebody has already listed on here called www.eaglerisetransformers.co.uk
They sourced me a replacement, black, sliding foot dimmer and a new on/off switch.
Bearing in mind the light retailed at £200.00 I have extended my light for many more years to come and my marriage as well (mrs wasn't happy when it packed up) and the price paid was well worth it and I got free p+p!!

David Clarke of Dudley, West Midlands., January 2011

Hi,

Give these guys a try. www.eaglerisetransformers.co.uk
They are the only UK company to sell Chinese transformers.
They saved me a fortune.

Paul, December 2010

futher to mm's answer he should get with it,12x20w=240watts which is well over the rating of tranny which is 150watts. 10 watt lamps should be fitted, as peccavi suggests reduce lamp numbers to 8 to prove a point

steve.e, November 2010

Thanks mm

Peccavi, November 2010

if your light came with the 20 watt bulbs,then its ok,the trannie will run them ok,this works out at 12.5v per lamp,and i beg to differ peccavi,most modern trannies have a toc fitted,so if they overheat they cut out,then reset themselfs when cooled down,you really will have to get with it mate,:-).the electronic trannies wont pass any current if a bulb blows,so you cant test them with a meter,

mm, November 2010

Well - maybe mm is correct and I'm wrong here.

"Secure" does not necessarily mean good - sometimes lazy people just screw a terminal through the plastic sheath to make a connection i.e. they don't always strip back the insulation - this is why I suggested dismantle, inspect and remake - but no matter.

The total wattage of the load (the lamps) should be within the rating of the transformer - if the loading is too much this may be the cause of your problem - you might remove a few lamps to bring things into a better relationship and see what happens - you may reduce the wattage by using lower power lamps - you may fit a bigger transformer - you may run two transformers in parallel.

It costs nothing to dismantle and inspect the connections.

Good luck...

Peccavi, November 2010

Thanks for your comments. All the connections were secure when I removed it.
I have noticed that the light has 12x 20Watt bulbs (It came with them fitted 4 years ago from John Lewis). On the transformer it states Model: KTB-150 35-150W/VA.
Has it been overloaded all this time? If so, should I replace them with 12W bulbs, if they are available?

Peter B, November 2010

It may be so - the transformer being "on the way out" but I doubt it - in my working life I have never encountered an intermittent transformer - they either work perfectly - transforming away - or they stop working when a winding goes open circuit.

The symptoms you report are more consistent with a heat-related poor connection - it it were my fitting I would dismantle, examine and remake all the connections. It might even be a poor connection at the transformer but transformers themselves are usually good or bad - they have no mechanism to self-repair.

Peccavi, November 2010

the transformer is on the way out

mm, November 2010