dmc@videovax.Tek.COM (Donald M. Craig) (06/14/88)
I am looking for feedback on the quality and reliability of the slide latch mechanism used on the DB-15 ethernet connectors. I have used these myself for the past five years, and have discovered a number of problems with them. Additionally, various nasty remarks about these connectors have surfaced on the net from time to time. 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, and the Tektronix representative submitted a note from me outlining my experience and problems with the ethernet slide latch connector. Sun Microsystems also has a representative on the RP-125 committee. He has asked the component engineer for connectors at Sun if there was any data concerning the mechanical integrity of the slide latch locking mechanism used in the ethernet connector. Here is the response: "I am the Component Engineer for connectors at Sun. In regards to your question concerning the Ethernet DB-15, these are used through out industry by the millions, in many applications. I am not aware of any significant problems with mechanical integrity of the lock, or for that matter with the connector in any aspect. If the connector is properly installed and handled in a semi-reasonable manner you should not have any problems. As far as Sun is concerned, usage of D-Sub connectors in general, that is various sizes and configurations, will probably increase. When all things are considered it often turns out to be the best way to go! Hope this helps!!!" In the face of this informal statement by Sun's component engineer, I now need data about other people's experience with the DB-15 slide latch ethernet connector. Help save another standard from the same fate! Please send your comments email to: dmc@tv.tv.tek.com or tektronix!videovax!dmc Thank you, Don Craig Tektronix Television Systems
roy@phri.UUCP (Roy Smith) (06/14/88)
dmc@videovax.Tek.COM (Donald M. Craig) writes: > I am looking for feedback on the quality and reliability of > the slide latch mechanism used on the DB-15 ethernet connectors. In a nutshell, they suck! There is no doubt that the single most common cause of problems in our entire network (19 Suns, a Vax, and maybe a dozen Macintoshes and PCs) is loose ethernet tranciever cables, particularly on the backs of Sun-3/50's which provide no mechanical support for the cable at all. On our rack-mount systems, we support the cables with cable ties to various convenient supports. On our deskside suns, we've constructed assorted mechanical strain reliefs. Some of our 3/50's seem to be OK with just wedging the cable behind a desk but some are a constant cause of trouble. For the worse ones, we install a support bracked we've designed which helps a little (it's just a plexiglass bar notched to fit on the card extractor ears and with cutouts for the various cables and attachment points for cable ties in the appropriate places). > "I am the Component Engineer for connectors at Sun. In regards to your > question concerning the Ethernet DB-15 [...] I am not aware of any > significant problems with mechanical integrity of the lock, or for that > matter with the connector in any aspect. I'm not given to public flamage, but this guy must have his head firmly wedged in a dark place. If he's not aware of any problems, it because he hasn't been listening. I've complained loudly about this on the net before. I've complained to Sun field service. I've complained to Sun tech support. Clearly those complaints havn't gotten back to the right people. The stupid little stamped sheet metal clips are simply not strong enough to secure a connector with a big fat, heavy, and fairly stiff tranciever cable on it. As long as the cable is secured so if can't move if accidentally moved, it's OK. For example, on the tranciever ends, we lash the cable to the main ethernet trunk cable with 2 (or sometimes 3) wire ties a few inches away. But on systems which might move a little (like a deskside Sun on wheels), or in situations where the cable might be disturbed (like hanging off the back of a desk) forget it. What was wrong with good-old RS-232-style screws? Or, if they really wanted a tool-less installation, why not Macintosh-style knurled screws, or maybe even centronics-style wire bails? We recently got a 3-Com 3C503 ethernet card for an IBM-PC. The connector is a bit different, with screw holes instead of binding posts. Unfortunately, to use the screw holes you need a special adaptor bracket which I havn't been able to locate yet (OK, we just got the thing; I havn't had a chance to look very hard). It looks like it might be a bit more secure. Our Interlan ethernet board for the vax has a slight variation on the slide connector which looks like it might be marginally stronger (it has small extra ridges along the sides), but I doubt it would still be strong enough if we weren't able to lash the cable to various places in the vax's rack frame. I really don't know what the DIX guys had in mind when they designed this connector. Administering a network is hard enough without having to worry about which $5 connector is falling out. -- Roy Smith, System Administrator Public Health Research Institute 455 First Avenue, New York, NY 10016 {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net
cliff@se-sd.sandiego.NCR.COM (Cliff Bamford) (06/15/88)
The problem is that it's impossibly impractical to give that connector
"reasonable care" in the field. Regardless of type, connectors always
seem to be just-barely-visible and just-barely-out-of-reach. The D-sub
requires good visibility (to tell which way the slider is slid) and
good tactile access to [un]couple. Since these conditions rarely obtain,
THE !#@$%&* CONNECTER DRIVES PEOPLE CRAZY.
Which is one of the reasons you see so many of them torn asunder, at
which point they become worse than useless. Except as mute testimony
to the limits of human patience.
--
cliff.bamford@sandiego.ncr.com (619)693-5724 {ucsd,cbosgd}!ncr-sd!se-sd!cliffron@topaz.rutgers.edu (Ron Natalie) (06/15/88)
Yep, by the way, we've gone and replaced the slide clips with the good old RS-232 screws and threaded inserts on all the Ethernet cables of importance. -Ron
bzs@bu-cs.BU.EDU (Barry Shein) (06/15/88)
I'll second Roy Smith's gripes about those slide-latch ethernet connectors to quote Roy: "In a nutshell, they suck!" Actually, if there were some negative pressure they might work... We have around 100 Suns here and other assorted items (this lousy slide-latch is not unique to Suns by any means, it's ubiquitous) and they're always falling out, the worst catastrophes occur when they fall out of centralized server machines, we've been out for hours and hours while some poor operator tries to figure out what the problem is (they're learning, we're all learning.) Worse, much worse, it falls out of MY SUN all the time, like when I swing my chair around to gulp coffee or some other critical maneuver and brush the deskside tower, to get it to stay back in I have to re-arch the cable at a precarious angle so it provides pressure towards the plug. Now *that's* unacceptable, the public be damned. I'll also add a vote to the Mac-like knurled screws, that would be the ticket. -Barry Shein, Boston University
bae@ati.tis.llnl.gov (Hwa Jin Bae) (06/15/88)
In general, I don't like DIX 15 pin adapter without any secure screws.
My Symmetric 375 comes with 9 pin output which can be interface to
regular transceiver with a 9 pin to 15 pin drop cable. You can use
RS-232 like screw attachment with it, and it's so much nicer than SUN's
way of doing attachment. But then again you can always use "Crazy Glue"
or something... 8-)
---
Hwa Jin Bae | Standard excuses...not responsible.../dev/null...etc.
Control Data Corp. | (415) 463 - 6865
4234 Hacienda Drive | bae@tis.llnl.gov (Internet)
Pleasanton, CA 94566 | {ames,ihnp4,lll-crg}!lll-tis!bae (UUCP)dewey@execu.UUCP (dewey henize) (06/15/88)
In article <5047@videovax.Tek.COM> dmc@videovax.Tek.COM (Donald M. Craig) writes: >I am looking for feedback on the quality and reliability of >the slide latch mechanism used on the DB-15 ethernet connectors. [ Info on use of the info... } >Sun Microsystems also has a representative on the RP-125 committee. >He has asked the component engineer for connectors at Sun >if there was any data concerning the mechanical integrity of the >slide latch locking mechanism used in the ethernet connector. >Here is the response: > >"I am the Component Engineer for connectors at Sun. In regards to your >question concerning the Ethernet DB-15, these are used through out >industry by the millions, in many applications. I am not aware of any >significant problems with mechanical integrity of the lock, or for that >matter with the connector in any aspect. If the connector is properly >installed and handled in a semi-reasonable manner you should not have >any problems. As far as Sun is concerned, usage of D-Sub connectors in >general, that is various sizes and configurations, will probably >increase. When all things are considered it often turns out to be the >best way to go! Hope this helps!!!" > >In the face of this informal statement by Sun's component engineer, >I now need data about other people's experience with the DB-15 slide >latch ethernet connector. Here at Execucom we have a slightly different term for this 'device'. I won't put it out on the net, however, since this probably isn't the place to put adjectives regarding personal ancestory or public sexual habits. Suffice it to say that if the person who designed the slide latch connector were to come here and visit, his/her employer should only buy a one-way ticket - we'd be able to ship what remains there were back in a shoebox! Seriously, those things are a joke. When each and every part is made to exact and perfect spec, they seem to work ok (at least until you touch them in some fashion). The ones we got with at least 3 of our Suns and the cables that we also got from Sun seem to be made to different specs entirely. We had to do a good bit of reverse engineering to get them to handle the normal vibration of someone merely walking in the office (concrete floors). Junk em. Use screws. Please, since you are protecting this 'Component Engineer', help him/her/it :-) become aware of 'significant problems'. -- =============================================================================== | execu!dewey Dewey Henize @ Execucom Systems Corp 512/346-3008 | | You don't think my employer APPROVES of these ideas, do you?? Sheesh! | ===============================================================================
root@sbcs.sunysb.edu (root) (06/15/88)
In article <3352@phri.UUCP>, roy@phri.UUCP (Roy Smith) writes: > dmc@videovax.Tek.COM (Donald M. Craig) writes: > > > "I am the Component Engineer for connectors at Sun. In regards to your > > question concerning the Ethernet DB-15 [...] I am not aware of any > > significant problems with mechanical integrity of the lock, or for that > > matter with the connector in any aspect. > To the "Component Engineer" at Sun: I submit Sir, that you must not use your own product. At Stony Brook we have ~100 Suns of mixed types and I can attest that the metal slide lock causes us NO END of trouble. > What was wrong with good-old RS-232-style screws? Or, if they really > wanted a tool-less installation, why not Macintosh-style knurled screws, or > maybe even centronics-style wire bails? We recently got a 3-Com 3C503 I would like to see a connector like the one used on the uVAX (?) console cable: Long screw posts with a knob on the end that allows finger tightening of the screw. I understand that the slide is somehow a standard, but if it "don't work" then fix the bloody thing. > Roy Smith, System Administrator > Public Health Research Institute > 455 First Avenue, New York, NY 10016 > {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net Rick Spanbauer SUNY/Stony Brook
robert@ATOM.HPL.HP.COM (Robert Michaels) (06/15/88)
> The stupid little stamped sheet metal clips are simply not strong >enough to secure a connector with a big fat, heavy, and fairly stiff >tranciever cable on it. As long as the cable is secured so if can't move if >accidentally moved, it's OK. For example, on the tranciever ends, we lash >the cable to the main ethernet trunk cable with 2 (or sometimes 3) wire ties >a few inches away. But on systems which might move a little (like a deskside >Sun on wheels), or in situations where the cable might be disturbed (like >hanging off the back of a desk) forget it. > > What was wrong with good-old RS-232-style screws? Or, if they really To me the problem is that the little clips are "standard". I would be very surprised if a vendor will have enough courage to promote something more effective. To alleviate your problem you could try using a lighter weight transceiver cable. For us most transceivers are within 5 meters of the host. For short runs you don't need these really big fat cables. I think several vendors build these short lightweight transceiver cables ( yes even HP does). - Robert Michaels HP Labs
bjw@WILMA.BBN.COM ("Benjamin J. Woznick") (06/15/88)
I would like to second most of the comments that have been made about the slide connector. The problem with the ethernet is compounded by the size and stiffness of the cable. The only quibble I have with the other comments is that *I* can't really tell which way the slide wants to go even when I have it in full view. This has to be the worst human-engineered connector in the history of mankind. Ben Woznick
brescia@PARK-STREET.BBN.COM (Mike Brescia) (06/15/88)
> 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.
dlnash@ut-emx.UUCP (Donald L. Nash) (06/15/88)
In article <23340@bu-cs.BU.EDU>, bzs@bu-cs.BU.EDU (Barry Shein) writes: > > We have around 100 Suns here and other assorted items (this lousy > slide-latch is not unique to Suns by any means, it's ubiquitous) and > they're always falling out, the worst catastrophes occur when they ^^^^^^^ ^^^^^^ ^^^^^^^ ^^^ > fall out of centralized server machines, we've been out for hours and > hours while some poor operator tries to figure out what the problem is > (they're learning, we're all learning.) > It really gets interesting when the cable falls out just enough that the transmit wire gets disconnected but the receive wire is still in place. Then you have a machine which can listen but not talk. We had this happen on a MicroVAX II and almost went into a panic thinking the DEQNA had died. > I'll also add a vote to the Mac-like knurled screws, Me, too. Don Nash UUCP: ...!{allegra, seismo!ut-sally}!ut-emx!dlnash ARPA: dlnash@emx.utexas.edu BITNET: DLNASH@UTADNX, D.NASH@UTCHPC THENET: UTADNX::DLNASH, UTCHPC::D.NASH UUU UUU U U The University of Texas at Austin U TTTTUTTTTTTTTT Computation Center U T U TT T U U TT "The world is basically non-linear." UUUUUUU TT TT TTTT
wesommer@athena.mit.edu (William Sommerfeld) (06/16/88)
Actually, I would vote for something similar to what DEC uses for serial console cables: screw connectors with knurled knobs which have a slot for a screwdriver in them; this way, you don't _need_ a screwdriver to connect or disconnect them, but if you have a screwdriver, you can save some wear and tear on your fingers... - Bill
tpmsph@ecsvax.UUCP (Thomas P. Morris) (06/16/88)
In my limited experience with 3 hosts and 10 terminal servers and 2 DELNI's, those $#%@%&^%$ slide latches on the ethernet db15s are a real problem. As has been pointed out before, they are not built well enough to handle the actual weight and strain of the bulky transceiver cable, and they don't do their job as a result! Screws or knurled knobs or wire bails a la IEEE488 or Centronics would be a welcome relief! For our DELNIS we had to cobble together a custom strain-relief panel. For the servers we ended up tie-wrapping the cables to the frame supports. ----------------------------------------------------------------------------- Tom Morris BITNET: TOM@UNCSPHVX UNC School of Public Health UUCP : ...!mcnc!ecsvax!tpmsph ----------------------------------------------------------------------------- -- ----------------------------------------------------------------------------- Tom Morris BITNET: TOM@UNCSPHVX UNC School of Public Health UUCP : ...!mcnc!ecsvax!tpmsph -----------------------------------------------------------------------------
donegan@stanton.TCC.COM (Steven P. Donegan) (06/16/88)
How many of you fools still swear at slide locks, experience massive down time due to same? Well, less than a dollars worth of hardware and the guts to mess with the 'standard' (read holy) connectors will buy you much peace of mind. We convert ALL slide-lock cables and devices to SCREW-DOWN style. Haven't lost a single server or transceiver due to our un-holy conversion to a much more secure fastening method. -- Steven P. Donegan Sr. Telecommunications Analyst Western Digital Corp. donegan@stanton.TCC.COM
bob@rel.eds.com (Bob Leffler) (06/16/88)
In article <5047@videovax.Tek.COM>, dmc@videovax.Tek.COM (Donald M. Craig) writes: > Sun Microsystems also has a representative on the RP-125 committee. > "I am the Component Engineer for connectors at Sun. In regards to your .... > significant problems with mechanical integrity of the lock, or for that > matter with the connector in any aspect. If the connector is properly .... > In the face of this informal statement by Sun's component engineer, > I now need data about other people's experience with the DB-15 slide I can speak only from my own experience. We have many workstations located in the Engineer's cube at GM. Most of them are connected via a transceiver cable with the sliding connector that you are refering to in the previous article. We experienced at least one connector that was disconnected at least once a week. We would then have to dispatch somebody to the site, trouble shoot the problem, then plug the connector back in. Needless to say, this is very labor intensive and expensive. Almost all of our network problems turn out to be transceiver cables that are unplugged. I reported this problem to one of our vendors (Sun :-) ). I stated that in my environment, we would prefer a connector that could be fasten by screws. Local Sun Field service stated that they had received other similar complaints from other customers and that they would pass the suggestion back to their corporate office. -- Bob Leffler - EDS, GM Truck & Bus Account (313)456-5375 bob@rel.eds.com or {uunet!edsews, rutgers, umix}!rel!bob Opinions expressed may not be those of my employer.
donegan@stanton.TCC.COM (Steven P. Donegan) (06/16/88)
In article <8806150602.AA11768@atom.hpl.hp.com>, robert@ATOM.HPL.HP.COM (Robert Michaels) writes: > > > The stupid little stamped sheet metal clips are simply not strong > >enough to secure a connector with a big fat, heavy, and fairly stiff > >tranciever cable on it. As long as the cable is secured so if can't move if > >accidentally moved, it's OK. For example, on the tranciever ends, we lash > >the cable to the main ethernet trunk cable with 2 (or sometimes 3) wire ties > >a few inches away. But on systems which might move a little (like a deskside > >Sun on wheels), or in situations where the cable might be disturbed (like > >hanging off the back of a desk) forget it. > > > > What was wrong with good-old RS-232-style screws? Or, if they really > > To me the problem is that the little clips are "standard". I would be very > surprised if a vendor will have enough courage to promote something more > effective. To alleviate your problem you could try using a lighter weight > > - Robert Michaels > HP Labs Our experience has shown the vendors we deal with to be very flexible. TCL and Bridge Communications have both agreed to sell us 'positive attachment' cables and interfaces (on the server and the transceiver). I really liked Bridges naming this option as 'positive attachment' :-))) The original transceiver cables used a cast slide rather than a stamped sheet metal slide - the casting was much thicker and did provide a somewhat firmer connection. Every cable, transceiver, server and multiport fan-out that we have used at WD have been possible to convert to screw-downs. The hardest to convert so far was the BICC multiport fan-out; this was due to their extreme use of shielding and screws to hold the unit together - it takes about 20-30 minutes and a large amount of patience to convert this unit. The results are worth the effort. -- Steven P. Donegan Sr. Telecommunications Analyst Western Digital Corp. donegan@stanton.TCC.COM
andy@cs.hw.ac.UK (06/16/88)
Robert Michaels at HP Labs wrote... >To me the problem is that the little clips are "standard". I would be very >surprised if a vendor will have enough courage to promote something more >effective. About 3 years back we at Spider Systems decided that slidelocks were useless, and ever since have been fitting screwlocks instead to all our terminal servers, bridges and stuff. To let people attach to "standard" drop cables we provide a free 1 metre drop cable with a screwlock plug on one end, and a slidelock socket at the other. We call this a "tail". The point is that the slidelock part is then not at a strain position - it is a cable joint well away from the "immovable object" which the back of the box represents. It is twisting and bending which breaks slidelocks, not just pulling - slidelocks are fairly usable for in-line connections. Of course for people who are near to their network - for example in a rack with a DELNI, the length of the tail means you don't need another drop cable at all. Just to wrap it all up nicely, the screws have a knurled plastic knob on top for finger tightening. Of the thousands of products we have shipped, NOT ONE PERSON has reported a connector problem, and as far as I know NO-ONE has not bought something because we are "non-standard". We do get a lot of compliments though... Take heart, non-courageous HP - let good engineering win through! Andy Davis (andy@spider.uucp) Technical Director (andy@uk.co.spider) Spider Systems
dnwcv@dcatla.UUCP (William C. VerSteeg) (06/16/88)
The 15-pin ethernet connector with a sliding latch has been the point of failure for more problems on my networks than all other problems combined. The problems have gotten even worse recently. It seems that in search of the extra buck, most companies are using thinner and weaker sheet metal on the sliding lock. This bends and causes intermittent problems. Do yourself a vavor and don't propigate this abomination to another hardware set. Standard Disclaimer Bill VerSteeg DCA
tsa@edai.ed.ac.uk (Tom Alexander) (06/16/88)
From article <3352@phri.UUCP>, by roy@phri.UUCP (Roy Smith): > dmc@videovax.Tek.COM (Donald M. Craig) writes: >> I am looking for feedback on the quality and reliability of >> the slide latch mechanism used on the DB-15 ethernet connectors. > > In a nutshell, they suck! There is no doubt that the single most > common cause of problems in our entire network is loose ethernet tranciever > cables, particularly on the backs of Sun's which provide no mechanical > support for the cable at all. I agree entirely with the above comment. These bent bits of tin, laughingly described as retaining clips, are completely useless. They may work reasonably well with light, flexible cables but they certainly do nothing when used with the heavy, stiff transceiver drop cables. >> "I am the Component Engineer for connectors at Sun. In regards to your >> question concerning the Ethernet DB-15 [...] I am not aware of any >> significant problems with mechanical integrity of the lock, or for that >> matter with the connector in any aspect. > > I'm not given to public flamage, but this guy must have his head > firmly wedged in a dark place. If he's not aware of any problems, it because > he hasn't been listening. I've complained loudly about this on the net > before. I've complained to Sun field service. I've complained to Sun tech > support. Clearly those complaints havn't gotten back to the right people. > > The stupid little stamped sheet metal clips are simply not strong > enough to secure a connector with a big fat, heavy, and fairly stiff > tranciever cable on it. As long as the cable is secured so if can't move if > accidentally moved, it's OK. For example, on the tranciever ends, we lash > the cable to the main ethernet trunk cable with 2 (or sometimes 3) wire ties > a few inches away. But on systems which might move a little (like a deskside > Sun on wheels), or in situations where the cable might be disturbed (like > hanging off the back of a desk) forget it. > > What was wrong with good-old RS-232-style screws? Or, if they really > wanted a tool-less installation, why not Macintosh-style knurled screws, or > maybe even centronics-style wire bails? Does this guy never talk to field service people. We have complained bitterly to several field service engineers over the years. Hoods for this type of connector with knurled finger screws are readily available. I should add that Sun are not the only workstation supplier using this useless bit of bent tin as tranceiver drop cable retaining clamps. > I really don't know what the DIX guys had in mind when they designed > this connector. Administering a network is hard enough without having to > worry about which $5 connector is falling out. > -- > Roy Smith, System Administrator > Public Health Research Institute > 455 First Avenue, New York, NY 10016 > {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net
roy@phri.UUCP (Roy Smith) (06/16/88)
wesommer@athena.mit.edu (William Sommerfeld) writes: > screw connectors with knurled knobs which have a slot > for a screwdriver in them Yeah, but... make sure you implement it right. I've seen some connectors of the type William is talking about in which the knurled plastic grip was longer than the metal screw shaft inside and the screwdriver slot on the end was nothing more than an indentation in the plastic; stick a screwdriver in it and turn and all you end up doing is making shreaded plastic. Also, while I'm on the subject, let's make those screws and threaded sockets out of steel, not brass. I know you're not supposed to gorilla-ize the screws, but it doesn't take much force to strip the threads on a 4-40 brass screw. How much more does a steel 4-40 screw cost than a brass one in quantities of thousands? A few tenths of a cent? How much does it cost in valuable time each time you strip one and have to fight to the the connector out? Tens of dollars? And one more thing, please, please, please, please, don't attach the threaded sockets with nuts which turn in the same direction as the screws on the connectors! Anybody who doesn't know what I'm talking about should take a look at Inmac part number 853 (female mounting screws). For an example of how to properly design a threaded socket, take a look at the back of a humble ADM-5 or ADM-3 -- steel sockets embedded so they can't come loose when you unscrew the connector. Hey, I'm sorry if I seem to be getting all hot and bothered about such a trivial thing but it's time the computer industry realized that this is important and it's not worth trying to save a buck or two on the connectors for a $100,000 piece of equipment (or even a $500 one). I used to think this stuff got designed so badly because nobody really cared; once I found out that Sun actually has a component engineer in charge of connectors, I just flipped! If Sun has one, I'm sure DEC and IBM and everybody else does too (maybe bigies like DEC and IBM have whole rooms full of connector engineers?). Damned if I can figure out what they do. -- Roy Smith, System Administrator Public Health Research Institute 455 First Avenue, New York, NY 10016 {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net
raj@GLACIER.ICS.UCI.EDU (Richard Johnson) (06/17/88)
We have a lot of Sun fileservers around here and thus we've had a lot of problems with the transceiver connectors. The problem with Sun equipment in particular is that the fashion in which the connector is attached to the outside of the ethernet board (same thing goes for the ethernet connector on the CPU board). The screws onto which the slide connector is supposed to catch are mounted on the OUTSIDE of the board whereas the connector itself is mounted on the INSIDE. This means that the transceiver cable connector can't make full contact with the one on the board. (I tried to draw this in this message but it's too difficult.) The problem is that the pins on the transceiver cable connector side don't go all of the way into the holes on the board side because the catches for the connector are mounted too far away from the top of the board side connector. (Take a look at it, you'll see.) We finally just removed the screws from both sides as well the slide latch and replaced them with screws going straight through the cable side connector and into the nuts on the board side connector. This allows the connectors to be close enough together so that they make good contact. We've never had problems with any that we done this to so this is the first thing I do whenever we start having problems now. If Sun would solve the basic problem, however (as described above) I think the latches would be just fine. ----------------------------------------------------------------------------- Richard A. Johnson raj@rome.ics.uci.edu (Internet) UCI ICS Assistant Technical Manager ucbvax!ucivax!raj (UUCP) Postmaster / Network Services raj@tertius.ics.uci.edu (via Nameservers)
phil@amdcad.AMD.COM (Phil Ngai) (06/17/88)
In article <3356@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >I used to think this >stuff got designed so badly because nobody really cared; once I found out that >Sun actually has a component engineer in charge of connectors, I just flipped! >If Sun has one, I'm sure DEC and IBM and everybody else does too (maybe bigies >like DEC and IBM have whole rooms full of connector engineers?). Damned if I >can figure out what they do. Well, if you don't care why should they care? If you care, let them know. Make a case out of it with your salesman. Tell people like Sun that they should follow the ISO 802.3 international standard for transceiver cable connectors and mount them on the OUTSIDE of the panel. Like DEC does. Many people do not realize how important this is. Many people have not looked at the connection system carefully. -- I speak for myself, not the company. Phil Ngai, {ucbvax,decwrl,allegra}!amdcad!phil or phil@amd.com
jmg@cernvax.UUCP (jmg) (06/17/88)
One other funny (correlates with the bread and butter law): on the fan-out units which we have the connector has to be pushed upwards to lock. From then on some evil force (Isaac Newton had a word for it!) is constantly trying to unlock it again, and each slight movement helps this evil force. Oh, how simple it would have been to invert the connector. The force is against you! -- _ _ o | __ | jmg@cernvax.uucp | | | | _ / \ _ __ _ __ _| jmg@cernvax.bitnet | | | | |_) /_) | __/_) | (___\ | (_/ | J. M. Gerard, Div. DD, CERN, | | |_|_| \_/\___ \__/ \___| (_|_| \_|_ 1211 Geneva 23, Switzerland
billq@ihlpe.ATT.COM (Quayle) (06/17/88)
In article <8806151700.AA03253@ucbvax.Berkeley.EDU>, brescia@PARK-STREET.BBN.COM (Mike Brescia) writes:
#
# > 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.
Outside the Ethernet realm, and in an industry that required a connector that
would withstand strain due to cable motion, we used an Amphenol MS connector.
For those unfamiliar, this is a round, keyed connector, with a screw-on shell.
Those things would withstand any ammount of cable motion (not to mention some
pretty nasty envrironmental hazards), without the least bit of wear or loss of
contact.
BTW, as our net grows to nearly fifty nodes, I'm still the only one I trust
manufacturing and installing those $*^%*&^*$ drop cables!!!
W.R. Quayle
AT&T Bell Labs.
Disclaimer: I have no connection (beit slidelock or otherwise) to any company
mentioned in my reply. My ideas are my personal feelings only!billq@ihlpe.ATT.COM (Quayle) (06/17/88)
<<STEAM ON>> First off, I'd like to know who designed the slide-lock mechanism. Did they get fired for it? If not, they should have! I would gladly change every connector on my net to something real if a new standard was aggreed upon. Second point: Who the heck is responsible for positioning the watchdog reset button on the Sun 3 Motherboard directly next to said-flimsy-*ss-switch? This individual needs shock therapy! <<STEAM OFF>> W.R. Quayle Lab Coordinator - 52182 AT&T Bell Labs Naperville, Il Disclaimer: These thoughts are all mine! (My that felt good!)
dvw@thumper.bellcore.com (Dan V. Wilson) (06/18/88)
In article <22108@amdcad.AMD.COM>, phil@amdcad.UUCP writes: > Well, if you don't care why should they care? If you care, let them > know. Make a case out of it with your salesman. Tell people like Sun > that they should follow the ISO 802.3 international standard for > transceiver cable connectors and mount them on the OUTSIDE of the > panel. Like DEC does. Many people do not realize how important this > is. Many people have not looked at the connection system carefully. > > -- > > I speak for myself, not the company. > Phil Ngai, {ucbvax,decwrl,allegra}!amdcad!phil or phil@amd.com Phil is absolutely right. My experience with the DB-15 connectors and the <insert expletives> slide locks is that they work fine IF the slide is mounted directly on the connector body (are you listening, Sun?) AND the connector is mounted on the outside of the panel AND the posts are the proper height AND the slide hasn't been strained or bent AND the phase of the moon and several other planets is correct. My favorite fix is to make a short stub cable out of DB-15 crimp on connectors and a few inches of 15 conductor flat cable, and to insert this short cable between the tranceiver cable and the piece of equipment. I've found that this has eliminated problems with the transceiver cable connections on Sun 3/75's and 3/160's, which are notorious for having a thick panel between the connector and slide lock on the Ethernet connection. I know, I know, the stub cable probably radiates, but I don't care. I've found that the friction grip from the crimp-on connectors is usually better than that provided from the connector plus slide lock. One should note that Sun may use lots of DB-series connectors, but they DO NOT use slide locks to my knowledge other than on Ethernet connectors. They always use another type of lock, either the 'wings' (can't think of a better term), or screws. I find myself wishing that I believed in Hell just so I could hope the designer of the slide lock and the connector engineer at Sun could roast there. Honorable mention should probably go to the writers of the two original Ethernet specifications for not specifying the transceiver connectors more fully. Dan Wilson dvw@bellcore.com bellcore!dvw
roy@phri.UUCP (Roy Smith) (06/18/88)
andy@cs.hw.ac.UK writes: > About 3 years back we at Spider Systems decided that slidelocks were > useless, and ever since have been fitting screwlocks instead to all our > terminal servers, bridges and stuff. A big "Thank you!" to the folks at Spider for having the courage to stand up in public and (proudly) admit that they did something non-standard because it was better. Not just better, but a hell of a lot better, and downward-compatable to boot! Now all we have to is get all the other network vendors to do the same thing (and get catalog houses like Inmac to start stocking screw-post drop cables). Sun may say "The network is the computer" but I say "the connector is the network"! Could you imagine if 50 companies a day, I say 50 companies a day stood up and said "slide locks suck" and started shipping screw-in ethernet connectors? I'd be a revolution, friends. (Apologies to Arlo Guthrie). -- Roy Smith, System Administrator Public Health Research Institute 455 First Avenue, New York, NY 10016 {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net
roy@phri.UUCP (Roy Smith) (06/19/88)
phil@amdcad.UUCP writes: > Tell people like Sun that they should follow the ISO 802.3 international > standard for transceiver cable connectors and mount them on the OUTSIDE of > the panel. (To the tune of "look what they've done to my song") Look what they've done to my SUN, DIX, Look what they've done to my SUN. They've gone and moved, the cable plug, From the outside to the in, DIX. Look what they've done to my SUN... > Like DEC does. Come to think of it, we've had a lot less trouble with out DELNI than with our Suns. Warning: do not construe the previous sentence to mean that I actually think the slide locks might work right if constructed strictly according to the specs. All I'm saying is that they wouldn't be as bad. > Many people have not looked at the connection system carefully. Perhaps, but I'll bet that lots of people have looked at the connection system angrily, obscenely, and with violent thoughts of destruction. -- Roy Smith, System Administrator Public Health Research Institute {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net "The connector is the network"
steve@alberta.UUCP (Steve Sutphen) (06/20/88)
We have been using these slide lock connectors since before we installed Ethernet 5 years ago (they were also used on the HP 2621 terminals keyboards). While I will grant that we have had some problems with them, I wouldn't say that they have been a constant headache -- maybe our people take more care in the installation and use of equipment than at other sites. If someone is doing a new specification as was indicated in the original article then I think that they should take a serious look at the factors involved. I think that a major part of the problem is that 1) right angle shells are not as commonly available as they should be and people installing the cables don't bother choosing the correct connector (right angle vs strait). 2) the Transciever cable is part of the problem - it is very stiff, large and heavy. This excrabates all the other problems. I would not say that jack screws as are used on RS-232 connectors are completely fool proof though either. We have had our share of 1) stripped female locking nut 2) loose female locking screws because of binding of the jack screw, or simply beacuse the nut loosens (even when "properly" installed). For a while we would go through all the screws on new equipment and tightnen up the female locking screws. I even thought about putting locktite on some of the ones that were more problematic (on the old Sun-100 chassis). steve.
aledm@cvaxa.sussex.ac.uk (Aled Morris) (06/27/88)
I too *hate* the clip arrangement on ethernet connectors. The
most difficult manouver is trying to lever the sodding clip so
you can disconnect the drop cable from the back of a "deskside"
Sun, when there's something screwed firmly into port B, and you're
worried about hitting that reset button 1inch down (plus, of course,
you're leaning over the cabinet on your belly trying not to hit the
power switch with your knee) [fume fume...]
There are worse connectors...and those are the 3 pin mains leads,
with absolutely NO RETAINER WHATSOEVER [god, they make me so ANGRY :-)]
Forget about "ie0: ethernet jammed", one jerk (pun intended) and the
machine goes down, lock stock and disk heads. Proividing FSCK does not
make up for saving 50 cents on a decent screw-in cable lock.
And another thing---that stupid "off" switch on the front panel, it
really ought to be a key (with a "safe" position that disables L1-A).
I'm so glad that others apart from myself are complaining about these
stupid practices. Maybe we'll actually see some action from the vendors
on this one?
p.s. maybe this discussion ought to get moved elsewhere...?
Aled Morris
systems programmer
Janet/Arpa: aledm@uk.ac.sussex.cvaxa | School of Cognitive Science
uucp: ..!mcvax!ukc!cvaxa!aledm | University of Sussex
talk: +44-(0)273-606755 e2372 | Falmer, Brighton, England
"I'm living in the future/I feel wonderful/I'm tipping over backwards...
I'm so ambitious/I'm looking back/I'm running a race and you're the book I read"karn@thumper.bellcore.com (Phil R. Karn) (06/30/88)
> I'm so glad that others apart from myself are complaining about these > stupid practices. Maybe we'll actually see some action from the vendors > on this one? Don't hold your breath. Flushed with success in designing Ethernet transceiver clips, they're now all busily bringing you OSI. One feature I wish they had included in the Ethernet transceiver connector is a remotely-triggerable disconnect, similar to the explosively-driven bolt and cable cutters used on space launchers. (One was featured in 2010 as HAL's "emergency pull".) I'd wire them all to a big panel in my office. Then the next time somebody's broken host software sends out a bogus broadcast packet, I'd turn the switch, and... Phil