Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ucbvax!PARK-STREET.BBN.COM!brescia
From: brescia@PARK-STREET.BBN.COM (Mike Brescia)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Looking for comments on the 15-pin ethernet connector
Message-ID: <8806151700.AA03253@ucbvax.Berkeley.EDU>
Date: 15 Jun 88 13:49:18 GMT
References: <5047@videovax.Tek.COM>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
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>     I am looking for feedback on the quality and reliability of
>     the slide latch mechanism used on the DB-15 ethernet connectors.

>     The Society of Motion Picture and Television Engineers has a
>     standard known as RP-125 which specifies a parallel digital
>     television interface.  The connector for that interface is
>     a 25 pin D-type (DB-25) with a slide latch like the ethernet
>     connector.  The RP-125 standard is up for revision, ...

So far, I have seen people flaming the slide latch, but no comment on the
Dtype connectors.  While using screws to replace the slide latch helps in some
cases, the main problem seems to be that the long, narrow connector with 2
rows of pins cannot withstand stress from a heavy or thick or stiff cable.
There should be some analysis of why you should not use cable that is an inch
in diameter to contain 18 individually shielded twisted pairs for your
rs422/rs449 and try to connect it with a DC-37.

The slide latch can only handle a little stress on the long dimension, and can
handle none on the narrow dimension.  The DB15 would be ok with a ribbon
cable, because the ribbon is both light and flexible, and a well fitted slide
latch would lock it in place, but then you would not even need a lock because
the friction of the connector would keep it it.

So, if SMPTE is going to do it right, they need to consider the mechanical
characteristics of the locking mechanism, as well as the ease of connection
and disconnection.

Mike

disclaimer:  My degree is E.E., not M.E., so I am relating experiences, not
properly qualified professional opinion.