CMB24D RJ45 burns out USB 485 Adapter

[jfuller8400]

Hi All,

I've already started a help desk ticket with LOR about this but also wanted to ask it here too.  Tonight I started working with a new CMB24D board that I got at this summer's mad grab sale.  I set a new Unit ID (via the dip switches) and wanted to verify that I set the correct ID via the Hardware Utility.  So I powered it on and then plugged in a known working RJ45/USB485/USB cable (I had just used it to set some addresses on a couple of CTB16's).  When I plugged in the RJ45 to the CMB24, it's power supply fan immediately spun up like it was under load.  I also heard a fizz sound and smelled smoke.  So after hastily unplugging everything I noticed that the 485 and USB cable were extremely hot.  

After verifying that I had, in fact, smoked the 485 (I couldn't connect to the CTB I had just configured), I reset the ID on the CMB24D back to Unit 1 and did a visual inspection of the RJ45 jacks - no obvious problems.  Got out my spare 485 adapter and tried again.

Any guesses what happened next?  That's right, the power supply spun up again and I smoked another 485.  Sigh.......

Has anyone ever had a similar type of issue before?  The only thing I can think of is that there's some type of voltage issue coming out of the RJ45 jacks (and I did try both of them). 

Thanks for any help in advance.

 

[LOR Staff]

I see where we have already started the RMA for the board.  I looked up your order and see where you only purchased bare boards.  

1 - What power supply are you using with this CMB24?

2 - Are you 100% positive that you didn't hook it up backwards?  (swaped negative and positive)

[k6ccc]

Never had a problem with my CMB24D.  Although it's not being used in my show, I have done lots of testing with it.

 

[jfuller8400]

Hi Mike,  

Yup - 100% positive it's wired correctly (gotta love using color coded wires).  Voltage meter shows it's putting out about 12.4V and I've got a blinky red light on the card.  The power supply is a 360W unit (one of those silver box type with the terminal adapter).  While not outdoor rated, I've got it mounted in a CG1500 along with the card and then the whole CG1500 is put into a storage tub when it's placed out in the display.  It's worked well for me to keep the elements out (and I get rain, freezing rain, snow, ice, etc..)

I've attached a pic if that helps.

Thanks!

Joel

[LOR Staff]

Engineering replied back to your ticket, so I'll let them finish this up.

[jfuller8400]

I'd like to start by saying a big THANK YOU to everyone at LOR.  The service and turnaround time I received on this issue was nothing short of amazing (and I know this is everyone's busy time).  Especially since this ended up being a problem of my own making. 

So like many of us, I had mounted the PS on a plate in a CG1500 enclosure using the 4 screw holes in the bottom of the PS.  After LOR had already processed the RMA for the CMB24 and shipped out a new one, Engineering responded to me and said 'BTW - check your PS to insure there isn't any continuity between the ground and the +/- outputs'.  Ok, I thought - and proceeded to find out that I WAS getting continuity between the ground and the +/- outputs. 

Great, I thought, I'm responsible for smoking my board.  Dismounted the PS and just for grins and giggles (and it's good testing methodology as well) check for continuity again.  Only this time it wasn't there anymore.  Hummm.. Interesting I say.  I wonder if....   So I reconnected the PS back to the CMB24 and powered it up.  Blinky red light - so far so good.  Now the moment of truth.  Plugged in an RJ45 cable and low and behold the blinky red light turned solid!  Wow!  No smoke, no hot cables, everything looks normal.

I figure I'm on a roll but it's almost too much to hope for that all the outputs work.  Test each of the 24 channels and they all work perfectly.  AMAZING!  I managed to torture my board with some weird currents and it still survived!  The only think I can think of is that when I mounted the PS one (or more) of the mounting screws extended too far into the case and caused the short between the +/- outputs and ground.  I'm amazed it didn't blow the entire PS!

Just something to be aware of for those of us who assemble our own controllers as well as an example of just how great the engineering is on the products that LOR sells.

 

[TheDucks]

Was your Mounting plate Metal? Or were the screws too long and also touched the PCB inside the PSU?

Just trying to figure out what to watch out for. (have 2 @ CMB24D)

[jfuller8400]

It was a plastic mounting plate so I think some of the screws were just too long.

Like you said, just one more thing to watch out/test for.

[Jefffrompawpaw]

I just purchased my first CMB24D( I don't even have it in my hands yet)  if you could include a picture of what grounded where that would be awesome.  I purchased an enclosure and I don't know how to mount one the right way. I good picture of how the PS is connected to the board would be great too.  Thanks, Jeff

[jfuller8400]

The only picture I've got is the one I added on a previous post.  The PS was mounted from the bottom so I have no idea of what grounded inside it. I just know that when I took it off the mounting plate, the problem disappeared so I made sure to use shorter screws when I put it all back together.  The pic does show the wiring from the PS to the board, though.

 

[Mr. P]

All my power supplies are mounted with nylon screws, that is what they came with.