These lasers definitely do not have the advertised lifespan.  But,
fortunately, we have always gotten more than 50 hours of red line from
each.  Our laser gets used for at least a few hours every weekday (and
sometimes in the evenings or weekends) and we have needed a replacement
laser every 9-12 months; at one point we got a succession of bad lasers
that needed rapid replacement.  Often the red line does disappear, but
adjusting the back mirrors can usually bring it back.  This used to not be a
problem, but now with Cy5 becoming a very popular stain, we need a good
steady red line.  Running the laser at low power, even if this worked for
rhodamine (which it doesn't really), is not an option.  Also, before
BioRad replaced the AC power supply with a DC, this was not an option
since the horizontal banding was worse at low than at high power.
Over the years this discussion pops up every once in a while and the same
answers seem to be posted-- yes, this is a repetitive message.  Yes, we have
run through a number of lasers
and we could post anecdotes about the good ones (we have one now, but read
below), but overall, although these lasers work well when they are
working, they don't work for very long-- not 2000 hours!  Or weird
things happen.  Such as:  a few weeks ago the red line spontaneously
disappeared; tweaking the mirrors brought it back.  Or,
suddenly, without any warning, a few weeks ago the laser power dropped.
We turned the laser off and when we turned it back on it was working fine
and has been since.  Why doesn't BioRad install the low/high computer
controlled switch?
 
 On Wed, 10 May 1995, Colin Macqueen wrote:
> We are now re-installing Bio-Rad Australia's "replacement" K-Ar laser for I
> think the sixth time in just under three years as our original laser is
> still  problematical. Invariably it is the red line which fails within
> about 50 hours of use. I have put out a goodly number of distress calls and
> am only now realising the extent to which there has been a worldwide
> problem. Bio-Rad have always acknowledged the extent of MY problem and been
> very supportive but for commercial reasons or from genuine lack of
> knowledge have not informed me of just how extensive the problem seems to
> be.
> I routinely have a multi-meter attached to the laser head and during the
> course of a days work jot down the laser power and anode current values a
> number of times. We have the "cut-out" option on our laser head so will
> report if or if not a significant difference in life-time comes about. It
> wouldn't take much for there to be an improvement as far as I'm concerned!