Progress on the Prototype board.

[Mitch Newcomer <mitch@hep.upenn.edu>]

Hall D Electronics:

 
--> I found that the  hand wired  regulator that according to Ian's 
.bmp  picture is suppose to put out 2.15V  was rambling around and 
finally went to 1.33V
Happily there was a little green wire that needed to be re-soldered. ( 
The sympton was an irratic  USB  behavior. )

--> I think I've identified the source of the transient we see in the 
middle of the data collection as coming from the front end.   If I short 
the input or put a small resistor load across it I can get the noise 
down to 2 counts and the size of the  step on that channel is at least 
5X smaller.   This point is capacitively coupled to the input preamp.
-->  Hal,  it would be great if you could attach a  1Meg resistor to gnd 
at the input of the  preamp and disconnect the other components.  This 
will reference the input to gnd and we can see if the noise and sudden 
transients dissappear or reduce in size.   Then you can  start putting 
components back hoping to identify the source of the behavior.  

Ian--> We can successfully use  Nick's program to generate .xml files 
that program  different  widths of  rampup and ramp down and  reset, but 
we do not see any indication of  a signal on the spare line put in by 
Nathan.    When you have some time could you work with nathan to hand 
edit the .xml file to get the line to  trigger.  Then check Nick's 
program to see if you get it to generate the appropriate code.   I used 
the scope, triggered by ramp up to look for any sign of a signal on  the 
line that's supposet to control  the  ccd charge injector. An LVDS 
output switching with no termination resistor should be a fairly large 
 >1/2 volt signal.
                       --- Mitch