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[Gerard Visser <gvisser AT indiana.edu>]

Dear Jianing and Li,
	I think Zhenyu was proposing to have two bias lines through the inner cable to 
the patchpanel board. But, even so, some jumpers to allow a configuration of the 
T board that uses just one bias line, does seem like a good idea.
	About the IST type connector, I think it should be reliable, but it was 
mentioned that it may be fragile and easily damaged. I don't know. If anything, 
probably it was the solder connections to the hybrid that were easily damaged.
	I think if you use a connector that doesn't have screw retention features, you 
have to use some other standoffs/screws to support the T-board. But that's ok. 
And depending on the mechanical arrangement it may be necessary anyway.
	I think we'd agreed based on your voltage drop study that it will be sufficient 
to connect the remote sense lines on the T board, not route them through to the 
hybrids. So those three pins are not needed, 19 pins minimum.
	Yes a few pins per power and ground is nice - I think it isn't essential here 
but a good idea. 2 or 3 is plenty (so that would be a 26 pin connector for 
instance). 44 is "too many". Of course 44 pins is fine if it fits.
        Sincerely,

                Gerard


On 2/19/2019 7:17 AM, 董家宁 wrote:
> Dear Gerard and All,
>    Thanks for all the comments!
>
>    1. Two biases for inner and outer hybrids:
>    We'll add a jumper between the two biases, and use shared bias for 
> inner/outer sensors as the default running scheme.
>    P.s. We notice that there are jumpers used in hybrid for IST. Does anyone 
> know the jumper type?
>    
>    2. Connector position & selection:
>    1) We'll move the two connectors to the same side in T-Board. Right now we 
> are working on it, and it seems like that keeping the current size is 
> practicable.
>    2) A survey about the connector selection will be carried out recently. We 
> will try to find the best choice.
>     (BTW the SAMTEC connector is reliable based on the previous experience, 
> change to other connector may bring some unknown risk. Suggestions are 
> welcome if one has better brand suggestion.)
>     
>    3. About the remote sense, do you mean the VSS_sense, VDD_sense and GND_sense? If yes, they are already connected. You can find them in pin 38, 44, 50.
>       So the minimum pin count for connector from T-Board is 22. But in this 
> case, there are just 3 pins connected to VSS, VDD and GND. Usually, more pins 
> will provide better power supply voltage if the size is acceptable. (In IST, 
> 7 pins are connected to VSS, 6 pins to VDD, 9 pins to GND ).
>
>    Best,
>    Jianing & Li
>
>
> > -----原始邮件-----
> > 发件人: "Gerard Visser" <gvisser AT indiana.edu>
> > 发送时间: 2019-02-19 05:02:46 (星期二)
> > 收件人: "LI YI" <li.yi AT sdu.edu.cn>
> > 抄送: star-fst-l AT lists.bnl.gov
> > 主题: Re: [Star-fst-l] Weekly FST meeting - 2/14/2019
> >
> > hi Li,
> >         Just a quick note to say I'll try to think about connector options 
> > but at this
> > time, when my work for FST is still entirely without funding, it is unlikely
> > that I can really attempt to search for an optimal connector. We hope the
> > funding contract will be in place sometime soon.
> >         I do not believe that changing the connector incurs any real risk, 
> > except
> > insofar as we don't really like the new type for some reason. Changing the
> > layout is not risky, and adding additional layers to the T-board should that 
> > be
> > necessary is not risky.
> >         I thought the connector used on IST should be ok; but if there is 
> > report that
> > it broke (traces, presumably) under connect/disconnect we should think 
> > strongly
> > about a better connector or layout. But I don't have info on such problems in 
> > IST.
> >         A smaller connector may exist, which could be helpful.
> >         A connector which affixes to the boards and may be the means of 
> > fastening the T
> > board to the detector assembly, as with the SSD "T-board" that I showed, may
> > exist. And I think it could be very helpful, in the case of both connectors on
> > one side for easy connection of the T-board+cable.
> >         One which is both smaller and has mechanical features would be nice, 
> > perhaps
> > there is something. That will be harder to find.
> >         The minimum pin count for connector from T board to hybrid by my 
> > reckoning is
> >
> > 8 for APV signals out
> > 4 for CLK & TRG to APV
> > 1 for RST to APV
> > 2 for SCLK, SDA to/from(SDA) APV
> > 1 for bias "SUB"
> > 3 (more better) for VSS, GND, VDD
> >
> > that is 19 min, better something like 24 or 26 or so. Not 44 for sure. There
> > isn't any harm in 44 pins if you've got room for it though.
> >         (BTW I didn't remark on it before - sorry! - but looking at the 
> > latest posted
> > schematic of the T board on 1/31, it seems the remote sense lines aren't
> > connected on the T board as we'd planned on doing? Do I misunderstand there? 
> > Or
> > else this needs some small change.)
> >         Sincerely,
> >
> >                 Gerard
> >
> >
> > On 2/15/2019 9:22 AM, LI YI wrote:
> > > Hi Gerard and All,
> > >
> > > Thank you for the documents!
> > >
> > > So the connector used in SSD is from
> > > http://www.nicomatic.com/product-amm_micro_connectors-81-en.htm
> > > Its pin size can go up to 50 pins. 44 pins are the minimum pins needed
> > > for FST. SSD connector pin distance is 1mm, which is larger than the
> > > previous one used in IST (which is 0.8mm). If SSD connector is more
> > > reliable than IST one, we can switch to SSD (the space saved would be
> > > small ~ 60/2*0.8mm-44/2*1mm = 2mm). Otherwise, we would prefer to use
> > > the same IST one to reduce the risk of error in drawing.
> > >
> > > Best,
> > > Jianing & Li
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > On Thu, Feb 14, 2019 at 11:18 PM Gerard Visser <gvisser AT indiana.edu> wrote:
> > > > hi Li,
> > > >           Here for reference is info on the SSD "T-board" like thing, that 
> > > > was mentioned
> > > > in meeting discussion just now.
> > > >
> > > >           Gerard
> > > >
> > > >
> > > > On 2/13/2019 6:02 PM, Ye, Zhenyu wrote:
> > > > > Dear all,
> > > > >
> > > > > We will have a meeting to discuss Forward Silicon Tracker tomorrow at 9am BNL 
> > > > > time. The meeting agenda and bluejeans info can be found at
> > > > >
> > > > > https://drupal.star.bnl.gov/STAR/blog/yezhenyu/forward-silicon-tracker-weekly-meeting
> > > > >
> > > > > Best,
> > > > > Zhenyu
> > _______________________________________________
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