Difference between revisions of "CDC 20 02 2008"

Revision as of 17:51, 12 February 2008

Shaper board

The 16 channel cable preAmp - shaper board arrived today at CMU. Time to take data. After connecting the the cable to the shaper board some problem showed up. Channel 1-2-3 (starting from 0) showed a gain that is a factor of 10 lower than the other channels. Worrisome is that before this behavior already showed up in channel 2 (1 month ago) but after reconnecting the cable it disappeared. Also now, sometimes channel 2 recovers but channel 1 and 3 always stay at the low gain. I saved some scope traces and I believe they are pointing towards a problem close to the 3M connector.

In figure 1.1 a CDC signal can be seen in a good channel (channel 0) in figure 1.2 a CDC signal is shown in a bad channel (ch. 3), notice the difference in the vertical scale.

figure 1.1: CDC signal out of a good shaper channel.

figure 1.2: CDC signal out of a bad shaper channel.

When injecting a signal in the shaper board no problem is visible. Injecting happens in a different input connector than the 3M one. In figure 1.3 and 1.4 one can see this for a good and bad channel respectively.

figure 1.3: Shaper in(blue)/output(green) when injecting a signal in a good channel.

figure 1.4: Shaper in(blue)/output(green) when injecting a signal in a bad channel.