Conformal coating on Jaguar RJ12 connectors causing problems?

[Vin]

We've been having issues, and finally figured out tonight that pressing on the cable/connector will get it to work. Someone at Vex mentioned last week that conformal coating on these new units were an issue dues to overspray on the connectors.

Any idea how to clean this off? Or are we allowed to pop these things open and hardwire the units together (as it's prob too late to order and replace RJ connectors on the PC-boards)?

[Levansic]

Do you have any pictures? Ours were all very clean, and the connection wires much more consistent than last year's.

[mjcoss]

We had exactly this issue. 80% of the rj-12 connectors simply didn't seat properly, way too much slop in the coonector so just wiggling the cable would cause the connection to drop out. Our solution was to take a zip tie and shim the rj-12 connectors. Need to get the right size zip tie but works like a champ and can be removed to replace cable or Jaguar. This worked better than other the option we were looking at: glueing them into place. I did look at maybe more robost rj-12 connectors but ended up with this simple workaround.

[Vin]

I don't have any pics of inside the connector, but between my original post and now, we've been back-and-forth with Vex have a few revelations...

- Using 2 brand new Jaguars (with the FIRST logo on them), we got CAN working (serial from PC to Jag, then 6p6c cable between both Jags).

- The problem is apparently with the older (TI-logo) Jags, and have not yet been able to get any pair to work with CAN.

- Corey at Vex informed me that the FIRST-logo units were conformal coated, and not the TI's, so that rules out the coating as being the problem.

I cannot trust zip-ties for this, as the robot will get banged around in competition. Only options I see currently are to change the connectors inside the TI Jaguars; hardwire to the TI Jaguars; or somehow scrape up some more $ for 3 more FIRST-logo Jaguars (the third for a reliable spare).

With the robot bagged, I don't have access to the TI units until competition, so that only leaves the third option. And yes we really want to use CAN.

[Levansic]

Ah-ha! The TI Jaguars from last year had a few QA problems. Specifically, the RJ-11 and RJ-12 ports had issues with under-sprung contact wires. Check out this thread for details and a fix:

http://www.chiefdelphi.com/forums/sh...d.php?t=100448

My team was in the exact same position last year, with respect to CAN. We desperately wanted to get away from the rats nest of wires that seemed to grow on our robots with PWM cables routing back to the digital breakout board. Nobody wanted to cut those cables for fear of being too short, or botching the terminations. CAN was a very attractive option that used inexpensive cables and terminations, that didn't require every controller being routed back to the breakout board.

We had the same connectivity problems you had. The above fix cleared up about 80% of the issue, but we still had a few cables that would jostle on the field, and lose contact. At the Las Vegas regional, we changed from a daisy chain to a star topology for the CAN network, and we've had almost zero problems since.

The whole point for us is to make the connections as reliable as they can be. We decided against directly splicing the connecting wires together, as we wanted the ability to change wires in the pits, in case of damage. Check this thread on how to make a "hub" for the CAN, which will give a much more reliable star topology:

http://chiefdelphi.com/forums/showth...t=99554&page=3

One important thing to note, if you go this route, is that Home Depot recently changed their vendor for modular jacks. They used to carry Leviton, who makes a very high quality jack. Now, they carry their own store brand, which is a made in China piece of excrement. Although these cost about the same as the Leviton, the quality of construction and functionality is significantly less. Lowes carries a Legrand branded version, but the termination on the back is not convenient for sequential wiring with the same bundle of wire. One other thing to pay attention to, is the labeling of the RJ-11/12 jacks as "Voice Grade" jacks, as most are used for telephone lines. Recently, some "Voice Grade" jacks have switched to the 8P8C connector we know as RJ-45. You can use a cable with a RJ-45 on one end, and a RJ-11/12 on the other, but this could cause a lot of frustration for the non-initiated, let alone the potential problems of shifting the wires by one slot, when crimping the plug.

Our team has bought a bunch of Leviton jacks from an online supplier. Specifically, they are Leviton Voice Grade 41106-Rx6, where the x is a color-specific code (W=White, V=Green, R=Red, G=Gray, Y=Yellow, etc.). This jack is very high quality and made in the U.S.A. Specifically, this part has a snug fit on the plugs and good contacts that stay sprung.