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Re: CDC Connectors
Hi Fernando,
Thank you very much for all the info. I forwarded your mail to Gary
Wilkin.
I believe I can more or less picture it and things on the connector side
look pretty complicated to me. I was wondering if we could not make a
second pcb (a very simple one) where we solder all the (24) signal cables,
grounding, shield braids to on one side. This pcb is being fed through the
end cover and on the other side it has the connector soldered to it which
could be sealed. Also Gary had some ideas but he is not in this week.
Couldn't we connect the HVB ground to the end-plate via the Al-plate?
Cheers,
Yves
/--------------------------------
/ Yves Van Haarlem
_--~~--_ /
/~/_| |_\~\ / Carnegie Mellon University
|____________| / Department of Physics
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__| __ |__ \ Pittsburgh, PA 15213
| ||. | == | | \ USA
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/__\ /__\ \ Fax.: +1 412 681-0648
~~ ~~ \-----------------------------------
On Sat, 2 Aug 2008, Fernando J. Barbosa wrote:
> Hello everyone,
>
> I have attached a pdf describing the edge card connector from EDAC. This is
> similar to the one Gerard suggested but in 0.156" contact spacing. The
> connector part number is 307-030-500-202, which is a 30 contacts on dual row
> with a HV rating of 1800 V AC rms, Thermoplastic Polyester insulator and
> $3.05. I searched for similar connectors and Sullins also has a similar one
> rated at 1800 V DC but with a different insulator (PPS Ryton). However, the
> cost for the Sullins part is five times higher at ~$15. The EDAC connector is
> stocked at Newark.
>
> Now for the assembly details which are based on Slava's drawings. Slava, I
> would appreciate if you could email your drawings to those on this
> distribution list.
>
> The assembly attempts to minimize the cable length from the straw to the
> connector:
>
> 1. 24 RG-174 cables are prepared as follows:
> a. Strip both ends so that there is the center conductor for soldering,
> insulation of center conductor, braid and outer insulation. Each is about
> .125 long so there are steps (different diameters).
> b. On the straw side, prepare as is now planned with solder ball and
> conductive rubber. Maybe a heat shrink piece could be applied to secure the
> conductive rubber cylinder and cover the shield in one step.
> c. On the connector side, slide each of the 24 cables into a small copper
> plate (perhaps a bit less than .125 thick) with 24 holes and solder the
> shield braids at the exit of the holes. The shields will all be connected
> together to the shield HV and to 2 connector pins. Solder each of the 24
> center conductors to the connector.
>
> 2. The connector has 24 pins connected as in 1.c above, the next 2 adjacent
> pins connect to the copper plate to the shield HV, as in 1.c above. The next
> two pins are left unconnected and insulated or cut. the final 2 pins are
> soldered to a cable to attach to the endplate for grounding (ground on card
> is connected to endplate in this way.
>
> 3. The back side (soldered connections) is sealed with the proper viscosity
> sealer and with low out-gassing characteristics (no silicone here). The
> finished part forms the connector assembly.
>
> 4. Connect all the cables from all the cable assemblies to the straws and
> endplate (grounds).
>
> 5. Attach dummy boards with straps to the edge card connectors on each of the
> cable assemblies.
>
> 6. Position the gas plenum Plexiglass cover and feed all the straps through
> their respective holes on the Plexiglass cover. Slide this cover while
> pulling or straightening the straps until the cover touches the connectors.
> Attach the connectors with screws, washer and neoprene seal washer.
>
> 7. Rotate CDC so that connector side is at top.
>
> 8. Apply sealer (see 3 above) around each of the connectors/plexiglass holes.
>
> In this way, we only need a short distance between the straws and the gas
> plenum cover. This is not very elaborate but I can provide a drawing if
> necessary to better explain this technique. Please note that if one of the
> wires in the straws brakes and shorts tripping the HV, all the 24 channels in
> the group will be off. This is required because the shields are also at HV
> and the RG-174 is not rated for this level of HV. So, this is inherently
> safe.
>
> There will also be an aluminum plate or aluminized mylar cover over the whole
> gas plenum and grounded for shielding.
>
> Please provide feedback so we can finish the design of the HVB PCB. The HVB
> PCB will have the HV distribution network, the connections to the preamp card
> connector, grounding, etc. The preamp card, as in the FDC, is removable from
> the HVB.
>
> Regards,
> Fernando
>