Shaper channel 3: OK again

[Yves Van Haarlem <yvhaarle@ernest.phys.cmu.edu>]

Hall D Electronics:

Hi,

I did the measurement you proposed and could not see any difference 
between channel 3 and the other channels. Then I reconnected the preAmp to 
the chaper and could not observe the 10x attenuation any more. So whatever 
it was, it disappeared.

Cheers,
 	Yves

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On Mon, 28 Jan 2008, Gerard Visser wrote:

> 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
>