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Modular connector snafu

Is there any standard for modular phone connectors? I suspect not since was looking up the 4p4c headset jack (referred to as RJ9, RJ10 and RJ22), I don't recall that any of the manufacturers indicated pin numbers. Of course, it also is complicated by whether the connecting cable is 1:1 or cross-over. RJ11 is often confused as it is wider and though has also 4 circuits connected, is actually spaced for 6 circuits.

Was connecting up a demo board this morning that used the 4p4c modular connector for the CAN bus. Cannibalized a connector and cord from an old telset. Became a smoke generator inadvertently. Luckily, no damage and all worked after I mirrored one of the sockets. The telco handset cord was cross-over type and luckily had enough impedance to get hot rather than killing anything else (5V and ground in it).

Reply to
Oppie
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ISO 8877

Pin numbering and wiring are controlled by the wiring standard, not the connector standard. That would be EIA-568A/B and such.

Or line reversal. Lots of ways to wire a connector.

Wider than what? All the various connectors from RJ11 (4 pin) to RJ50 (10 pin) have the same connector spacing. There are two (or 3 if you include the handset connector) sizes of connector, but there are also a bunch of bulges and slots that have been added to allow for custom connector keying.

That would be a telephone handset connector. Since that doesn't connect to the PSTN (public Switched Telephone Notwork), there's no official wiring system. If you're ever installed a Plantronics headset on a desk phone, you probably have noticed that there are switches to accommodate nearly every conceivable way to connect the 4 wires in the handset.

Radio Shack carries the connectors and tools.

A connection standard might have helped, but it still helps to use a DVM to check your wiring and connections. Otherwise, look into fuses and current limiters.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558
Reply to
Jeff Liebermann

These any help?

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"However, if the wire pair for the handset transducer and the wire pair for the handset microphone are each wired in a crossover arrangement, then both the transducer and microphone will function correctly; even if the handset has an electret microphone. Most telephone handset cords (cable assemblies) are wired this way."

As the Wiki article points out, the handset connectors have nothing to do (directly) with the PSTN so they are not registered.

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Reply to
Spehro Pefhany

Also, you can just look into the ends of the clear polycarbonate plugs- you can see the wire color codes.

As Jeff points out, the tools are available from all sorts of places and can be very inexpensive (starting at under $10, up to a few hundred or more for production hand tools).

Modular jacks are great- cheap, pretty reliable, positive retention, built in strain relief, easily and cheaply field-terminated. Too bad the female connectors are so enormous.

Reply to
Spehro Pefhany

Thank you Jeff and Spehro for your input.

Reply to
Oppie

And yet Motorola had the numbering reversed on all their radio communication equipment.

--
Failure does not prove something is impossible, failure simply 
indicates you are not using the right tools... 
nico@nctdevpuntnl (punt=.) 
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Reply to
Nico Coesel

I never noticed but I'm not surprised. I just checked the pin numbering on my various Rotomola radios (Maxtrac, Radius, SP50, MCS2000, etc that use an RJ45 mic connectors. They're all numbered backwards. Tradition must be maintained, even if it's wrong.

In about 1993(?), I stupidly was involved in a proposed standards group trying to hammer out a standard for the pinout and connections for RS-232 devices (mostly terminals, modems, and printers) using the RJ-45 connector. The problem was that about half of the manufacturers involved had numbered the 8 pins one way or the other. There was one vendor that even labeled the pins A thru H. Since everyone wanted to move on to more important arguments, it was decided to number from left to right, gold pins up, as viewed from the front of the receptacle. To the best of my knowledge, that became the de facto standard (because the proposed group never became official). It was amazing that the numbering scheme was ever accepted as there were numerous unsettled issues such as symmetrical DTE/DCE wiring and using

4/6 pin and 10 pin (RJ50) connectors. Proponents wanted the pins numbered from the center pins outward (odd numbers to the left) so that larger and smaller connectors could use the same pin numbers for the same functions. These were the same people and same logic that gave us the even stranger pin numbering found on DIN circular connectors.

Incidentally, in 1980 or so, HP drafting had managed to renumber the common DB25 connector on several pieces of RF test equipment. This was despite the numbers being printed on the connector. I was the one that noticed and brought it to their attention. There were several discussions where I had to convince a suit that this really was a problem. I got nowhere until I offered to wire the mating plug in accordance to the printed documentation instead of the connector standard and report on what blows up. That problem was handed to an HP engineer who wisely suggested that a manual addendum would be cheaper and easier than having HP sued by an irate customer. Addendums to the manuals with the correct pin numbering and a field service note was issued. At that point, I became suspicious and found several other pieces of test equipment that had misnumbered pins on some connectors. I passed on the bad news, but left the company before I could find out if anything useful had happened.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558
Reply to
Jeff Liebermann

I

Check out TIA-561

also:

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There it is.

?-)

Reply to
josephkk

Yep, that's what eventually floated to the surface. I bailed out very early, but kept an eye on what was happening. However, in 1987 the stock market ate the family fortune, and in 1989, we had a local 7.1 earthquake, causing me re-arrange my priorities. As I indicated, I may have the wrong date for my involvement. EIA-561 was approved in

1990, so my involvement must have been several years earlier. When I bailed out, it was far from settled.

Thanks for the interesting link. There was Digiboard, which probably owned the largest number of RJ-45 serial ports, but was initially non-standard. For full flow control and DCD modem control, Digi required a 10 pin RJ-50. Also, note that pin 1 was not used. Some manufacturers made the major pins software or jumper programmable, so their box could handle anyone's wiring scheme (for retrofits and forklift upgrades).

This one wired the connector correctly, but numbered the pins backwards: If you can think of a way to screw it up, someone had already done it.

More connectors and connections (mostly adapters to EIA-561): At least EIA-561 is RS-232 compatible.

However, that's not true for EIA-562 which is the wide voltage range version of EIA-561 allowing output voltage swings from +/-3.7VDC to

+/-25VDC. That was great for 5V logic, but won't work with 3.3V logic. So, the 3.3VDC interface chips now include a voltage boost to +/-4.5VDC to meet the spec. 
--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558
Reply to
Jeff Liebermann

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