Two fluorescent tubes turned off at the same time - likely cause?

[seanspotatobusiness]

I have a SAD lamp that is shown here. It has two halves, each of which contain two fluorescent tubes. One half of the unit switched off suddenly during use while the other half remains lit. What is a sensible response? Does one tube likely need to be replaced or both or something else?

 

[KTW]

Can you interchange the tubes?

 

[shrtrnd]

I don't know your control circuitry in this unit, but my experience with dual lamped flourescent lamps is that when one goes, you can just replace it without the requirement to replace both lamps.

 

[seanspotatobusiness]

I was concerned that maybe some component had caused both bulbs to fail and changing/swapping them might immediately destroy the new bulbs also. I will try swapping the potentially defective tubes with the known-working tubes as soon as possible (tomorrow) to determine what works and what doesn't. Thanks!

 

[seanspotatobusiness]

After spending over an hour with the whole unit switched off, all the tubes are lighting again. At the moment I'm guessing that a temperature sensor was triggered but I'm not really sure.

 

[shrtrnd]

When the bulbs are going bad, they are affected by the heating of the tube contacts when in use.
Your fixture seems a little on the fancy side, I'm wondering if you have some particular control circuitry in there that might be experiencing a problem.
Are you sure the bulbs themselves are seated properly and securely in their contact fixtures?
Yes, if you have ballast problems, you could damage new bulbs.
If you let the fixture cool, and when immediately energized it lights both bulbs; but one bulb goes out after the unit is lit for some period of time, ... I'd keep looking for the problem.