mr16 led bulb flashes on and off when warm?

retrofitblues

Newly Enlightened
Joined
Mar 31, 2011
Messages
3
Hi, I have just replaced 5 x halogen mr16 bulbs with 5 x 4w led mr16. I changed the transformer to a 2a led driver. 4 of the bulbs work fine but one keeps slowly flashing on and off after about 15minutes of being switched on. Ive tried changing the bulb but had same problem with new bulb. Is there any obvious reason why it would do this? I checked the voltage and its at 11.97 volts. Is it just faulty bulbs or is it the driver causing this? And light on this would be appriciated.
 

panicmechanic

Newly Enlightened
Joined
Nov 23, 2009
Messages
130
Location
Germany
I'm not an electrician, but I guess the MR16s come with their own drivers. These are typically made to run on 12 V unregulated AC current from a halogen transformer. Connecting them to an external led driver may bring trouble and might destroy either internal or external driver.
The solution would be to find a smaller halogen transformer, or to connect more MR16 led bulbs to the old transformer, bringing it closer to it's designed load.
 

Lynx_Arc

Flashaholic
Joined
Oct 1, 2004
Messages
11,212
Location
Tulsa,OK
It is either a socket or the power supply. In some rare cases when metal parts heat up they can expand and that changes the electrical contacts. This could possibly cause the power to go off till it cools down and the metal contracts to make contact again.
 

retrofitblues

Newly Enlightened
Joined
Mar 31, 2011
Messages
3
I'm not an electrician, but I guess the MR16s come with their own drivers. These are typically made to run on 12 V unregulated AC current from a halogen transformer. Connecting them to an external led driver may bring trouble and might destroy either internal or external driver.
The solution would be to find a smaller halogen transformer, or to connect more MR16 led bulbs to the old transformer, bringing it closer to it's designed load.

It's on a cable track light system so there are 5 fittings on it which at 4w a bulb makes a total of 20w, be hard to add enough bulbs to make it up to the 150w the old transformer needed. The led driver is 12v dc 2A so 25w max and is suppose to be more stable with these bulbs. But i'm new to this technology.

It is either a socket or the power supply. In some rare cases when metal parts heat up they can expand and that changes the electrical contacts. This could possibly cause the power to go off till it cools down and the metal contracts to make contact again.

This sounds more likely, I bought 18 bulbs in total and after swapping them all around ive found it is happening to 6 of them, the other 12 seem to work perfectly. So i think it must be faulty bulbs. It does seem an odd fault though as they work perfectly fine for 15-20 minutes and then they start to flash very slowly (they stay on for 3seconds then off for half a second then back on for 3 seconds...etc). But that would be in line with them getting hot and expanding i guess.

Thanks for responding....i think i'll dismantle one and see if I can see anything obvious inside.
 
Joined
Jul 15, 2007
Messages
590
It's on a cable track light system so there are 5 fittings on it which at 4w a bulb makes a total of 20w, be hard to add enough bulbs to make it up to the 150w the old transformer needed. The led driver is 12v dc 2A so 25w max and is suppose to be more stable with these bulbs. But i'm new to this technology.



This sounds more likely, I bought 18 bulbs in total and after swapping them all around ive found it is happening to 6 of them, the other 12 seem to work perfectly. So i think it must be faulty bulbs. It does seem an odd fault though as they work perfectly fine for 15-20 minutes and then they start to flash very slowly (they stay on for 3seconds then off for half a second then back on for 3 seconds...etc). But that would be in line with them getting hot and expanding i guess.

Thanks for responding....i think i'll dismantle one and see if I can see anything obvious inside.

THat sounds like an overheat condition on the driver. IF (I stress if) it were a VIPR222a driver, that is what happens- heats up to 100C, shuts down, comes back on as soon as it cools off.
 

Lynx_Arc

Flashaholic
Joined
Oct 1, 2004
Messages
11,212
Location
Tulsa,OK
THat sounds like an overheat condition on the driver. IF (I stress if) it were a VIPR222a driver, that is what happens- heats up to 100C, shuts down, comes back on as soon as it cools off.

one way of testing for overheat would be to get a can of compressed air and spray the driver with freon when it shuts down and see if it runs again if the shut off time is long enough to guage.
 
Joined
Jul 15, 2007
Messages
590
one way of testing for overheat would be to get a can of compressed air and spray the driver with freon when it shuts down and see if it runs again if the shut off time is long enough to guage.

Or.... just put the lights in the freezer and run them that way. If it takes longer to overheat/andor doesn't... well...
 

retrofitblues

Newly Enlightened
Joined
Mar 31, 2011
Messages
3
thanks for replies, it does seem to be the driver overheating. I dimantled several of them and ran them with the plastic driver case removed and they ran with no problems for several hours. Guess there just getting to hot trapped behind the heat sink. Is this just poor drivers or inadiquate cooling? I would have expected the leds to fail before the drivers if it was poor cooling?
 

dellayao

Newly Enlightened
Joined
Apr 10, 2011
Messages
12
Hi R,
I once ran into this kind of problem. It turns out that I chose a improper transformer. Did u use an electronic transformer? That is it! An iron core, magnetic or wire wound one would fix the problem. By the way the LED MR16 bulb is really awesome! [link removed - DM51]

MR16C3X1W.jpg
 
Last edited by a moderator:
Joined
Jul 15, 2007
Messages
590
thanks for replies, it does seem to be the driver overheating. I dimantled several of them and ran them with the plastic driver case removed and they ran with no problems for several hours. Guess there just getting to hot trapped behind the heat sink. Is this just poor drivers or inadiquate cooling? I would have expected the leds to fail before the drivers if it was poor cooling?

Many factors go into an engineering decision tree to produce a design that is marketed. You've found a situation that doesn't work, unfortunately.

I would look at either removing the plastic case of the bad one or replacing it. The sink or driver could just not be configured right- outside of tolerance- and should be replaced.
 
Top