In m, D. Nebenzahl said:
On 1/21/2009 8:06 AM TimR spake thus:

One thing sure, four tubes didn't reach end of life at precisely the
same time.

True; but if it has a newer electronic ballast, it may shut down all 4
bulbs if it senses that one of them is going out. Might be worthwhile
trying new bulbs first.

My experience with electronic ballasts for fluorescents is that they
don't do that. All bulbs going out at the same time is usually (in this
order) a bad connection, ballast failure, lack of grounding, or very
unfavorable conditions (sometimes including bulb-ballast mismatch).

2-bulb non-electronic ballasts usually have both bulbs go out (or
extremely dim) if one bulb fails. The bulbs are in series with each
other, though one is slightly bypassed by a small capacitor to assist
starting.

- Don Klipstein )