There's considerable variation in eraser UV intensity, distance from the
bulb surface to the silicon is critical.  The $39.95 DataErase (?) from
DigiKey puts the chip on top of the bulb, separation about .05 inches, and
will take about 4 minutes to make a 16C71 read erased but you should give
it an extra 4 minutes to get a good erase.  The older style erasers had
the bulb about a half inch above the chip and would take 30-45 minutes to
get a read-back as erased, so 60 minutes isn't out of line here.

The low presure mercury vapor bulbs used in most erasers will last several
thousand hours.  The Xenon flash erasers which can erase an eprom in
5 to 10 seconds use bulbs with a few hours lifetime.



On Fri, 20 Dec 1996, Jim Robertson wrote:

> At 09:05 AM 12/19/96 -0500, you wrote:
> >     The bulbs need to be replaced every few hours?  I've been using the
> >     same eraser for YEARS on almost a daily basis and it still works fine!
> >
> >     I don't have any problem with heat buildup, and I have had very little
> >     problem erasing 16C5x parts with about 45 minutes exposure.  I might
> >     be able to go shorter, but I haven't done much experimenting in that
> >     area.
>
>
> 45 minutes to erase a 16C5x part? 2 or 3 minutes (for the _5X_ parts) is to
> be expected on a reasonable eraser. May be you should be doing some more
> experimenting or perhaps you do have a problem after all.
>
> Jim
>