Re: Shaper channel 3

[Gerard Visser <gvisser@indiana.edu>]

Hall D Electronics:

Hi Yves,
	No, that channel should have same gain as the others. Of course it 
could have been broken by one of us, but at least I can say that I 
tested it before bringing it to you and all channels were ok/identical 
in their response.
	You can use the resistor/transformer matching widget in reverse, 
together with one of those 1 foot differential pair jumpers that you 
have, to feed a test signal (I suggest for instance a 1 MHz square wave) 
into the shaper board (at the 0.1" pin header connector which is located 
_behind_ the 3M connector at the front. Schematics are in 
GlueX-doc-736-v2 for your reference. Just compare the response of the 
suspect channel to others, they should all be the same.
	I postulate that there is a problem such as an open connection on the 
signal cable on one side of the differential pair for this channel. 
Please try to check that with a multimeter, although it is a bit 
difficult to probe it without some smaller test leads than you have.

	Gerard

Yves Van Haarlem wrote:
> Hi Gerard,
> 
> Do you remember changing the gain of channel 3 on the shaper (starting
> from 1)? I notice that the signals are plus minus 10x smaller compared to
> the other channels (also the noise amplitude is 10x lower). If so, how can
> i set this back?
> 
> (see also
> http://www.jlab.org/Hall-D/software/wiki/index.php/CDC_06_02_2008#3_Signals_with_shaper
> section 3 for scope traces)
> 
> Cheers,
>         Yves