Re: Cable + shaper board

[Gerard Visser <gvisser@indiana.edu>]

Hall D Electronics:

Hi Yves,
	I am suspecting this might be what you get if one side of the 
differential pair connection is open (for instance at the cable to 3M 
cable connector). I'll check this theory tomorrow, I have no more time 
today, sorry.
	Yes I can send a 2nd shaper board, it is on my list anyway to finalize 
the shaper board components (maybe we reduce the gain a little more, 
relative to the one I left you with).
	More tomorrow,

		Gerard

Yves Van Haarlem wrote:
> Hi Gerard, Fernando,
> 
> Today the 18m long cable arrived! Thanks.
> 
> After installing it a problem showed up with the shaper board. It was the
> same problem that showed up before: some channels have a 10x lower gain
> than the others (ch 1-2-3, starting from zero). It is a bit worrisome that
> before the problem showed up in only one channel and after a while it
> recovered but now 3 channels show it. More info and some scope traces can
> be found in:
> 
>         http://www.jlab.org/Hall-D/software/wiki/index.php/CDC_20_02_2008
> 
> To me it looks like the problem is somewhere near the 3M connector because
> when you inject signals using the other connector the problem does NOT
> show up. I used two different cables (the new one and the one Gerard made)
> and the problem persists.
> 
> For the moment we just take cosmics anyway + one read out channel is now
> used to read out the cosmic trigger using the NIM signal attenuator from
> Gerard.
> 
> Would it be reasonable to ship another shaper board to CMU soon?
> 
> Cheers,
>         Yves
> 
> 
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>                           /   Yves Van Haarlem
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