Re: Shaper Boards

[Gerard Visser <gvisser@indiana.edu>]

Hall D Electronics:

Hi Curtis,
	Yes, I'm intending to send you a board... I'm working towards this for 
the last few days. The final decisions about setting the gain and the 
cable equalization on the shaper boards are being made. Then we get the 
parts and I will fix up a board and send it to you asap. Fernando's 
group will at the same time fix up Simon's boards.
	I had some setbacks with making this work here in my lab, wasted a 
couple of days. That's why I'm not done yet.
	Nevertheless, I still suspect the problem you and Yves are having is to 
do with the integrity of the cable connection. Especially as Yves 
reports that all channels behave the same with a test pulse injected on 
the 2nd connector. So, I don't believe that the new shaper board will 
cure this issue - but it is logical to try it, especially since you need 
the replacement shaper board anyway to fix the gain and equalization 
which were not yet adjusted properly for the new preamp.

	Gerard

p.s. Your question about a simple fix prompts me, I should have said it 
earlier... Yves, I recommend that (with the preamp board connected and 
powered but with chamber HV off and no pulser or anything connected) you 
measured the DC voltages on the pins of the second (0.1" header) 
connector on the shaper board. I think you will find that the voltages 
on the problem channels do not match those on the good channels. This 
would basically confirm a cable/connector problem. You could then try to 
check the cable connections directly, though that may be a little 
difficult without some smaller multimeter probe leads than I believe you 
have.

Curtis A. Meyer wrote:
> Dear Gerard
> 
>    as Yves mentions late last week, several of the channels
> on the shaper board that we have here appear to not work.
> The noise is signifcantly larger than the other channels. You
> had mentioned that this might be an issue with the differential
> receiver part of the board.
> 
>     Is there a simple fix that we can do here for this, or can you
> send us a board where all the channels work? If it does come
> to sending us a board, getting it here quickly would be very good.
> 
>   thanks in advance - Curtis
> 
> --
> Professor Curtis A. Meyer        Department of Physics
> Phone:  (412) 268-2745          Carnegie Mellon University
> Fax:    (412) 681-0648            Pittsburgh PA 15213-3890
> cmeyer@ernest.phys.cmu.edu  http://www.curtismeyer.com/