Gel Image Background Problem Solved

L.T.Hollingsworth L.T.Hollingsworth
Mon Aug 4 16:18:25 EST 1997

Last month I posted a problem we were having with
the Gel Images on a 373XL where we were seeing a light blue
streaking and yellow dotted background. Many thanks to the 
tenacious Tom Westlake of PE/ABI for finding a solution.
	This particular background problem did not affect the data. 
It just made it VERY difficult to check the tracking and practically
impossible to retrack a "straight line" tracked gel.  The solution, 
changing the EMPHeight. Note that this does not change the data or 
signal strength for analysis.

What was tried ...
	adjust Gel contrast
	realignment of laser and liner
	replacing the PMT
	replacing the IO board
	GelDocII - doesn't work for Gel Images with new versions
	resending firmware
	running Norton Utilities
	reloading software Analysis v3.0 and Collection v2.0XL

The Apparent Cause ... Estimated Maximum Peak Height defaulting 
	to 100 ... sensitivity too high

The Solution ... Change EMPHeight to 1000

You can "do this at home"
In Analysis2.0 under the Gel Menu
	dialogue box for Preferences allows you to change the Estimated 
	Maximum Peak Height
If you have a Gel Image background problem, you can open the Gel
Image, check the EMPH under preferences and change it ... raise
the number for less sensitivity, regenerate the Gel Image.  Hmmm,
if the bands are faint, would lowering the EMPH enhance the bands?
Need to try this, anything to make retracking easier...(+:
Happy sequencing ya'll

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