NCE N12A2 decoder too wide ?

[mu26aeh]

I have two Atlas "Classic" locomotives, one a GP35, one a GP30.  I attempted to put a N12A2 decoder in the 35 the other night, went to put shell on and it was very tight.  Took off, checked things out, seemed top of loco frames was spread out, motor cradle was not latching in at top.  I squeezed the frames together to get cradle to snap in place, and ended up pinching the board, causing a short.  Now tonight, I go to put another one in the gp30 and same thing happens.  Install decoder, shell is tight fit, and cradle not latched in.  I did not squeeze frames this time, lesson learned.  Comparing to DC board, it seems the DCC board is just a bit wider.  Does anyone else have one to check on this ?  I'm going to contact NCE about it but thought I'd ask if anyone else noticed this or had issues lately .

[John]

I have a couple of the Digitrax decoders for GP30s .. still in package .. if you need them

[mu26aeh]

Here are comparison photos

First, the NCE decoder
20151229_161434 by Adam Henry, on Flickr

Secondly, the Atlas DC board
20151229_161455 by Adam Henry, on Flickr

[Big Train]

I've run into this before. After filing the sides of the pads the decoder now fits correctly in the frame. There will still be enough material on the pad for electrical conductivity. Perhaps some of the DCC "boffins" can chime in and express an opinion as to whether this is an acceptable practice. Don't be too aggressive when filing, the pads may lift from the PC board and as to whether this compromises decoder reliability in unknown. It's never happened in my experience. I'd rather have it slightly oversized rather than slightly undersized in this particular case.

Why there is differences in board width or thickness, even among decoder from the same manufacturer could be due to a number of things. Different production batches, changes in manufacturing specs, poor quality control maybe. I doubt there is a standard for DCC decoder min/max dimensions. In an ideal world some sort of statistical process control would be used to prevent dimension creep, but as we all know, it's not a perfect world.

Sometimes you have to use the military approach (probably the same approach used by armed forces personnel world wide ) of Adapt-Modify-Overcome.

Hope this helps.

[John]

You could also take a couple of swipes at the frame with a file or dremmel if you don't feel comfortable doing it to the decoder ..

[peteski]

If there are no traces or components in the area to be filed there is nothing wrong with filing down the PC board.  I do that often for various reasons.  It will be easier than filing down the frame.

[mu26aeh]

Problem is that the center portion is too wide as well.  Here is picture of the decoder I ruined when i pinched the frames together to where they should be. 

20151230_181135 by Adam Henry, on Flickr

I have sent NCE a message about it, but I'm guessing they are shut down like Digitrax until Jan 4.

[jagged ben]

It's amazing how bad so much of this stuff is.

[Wutter]

Looking at how the pads just connect to one trace each on the board

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If NCE doesn't come through with a decoder replacement or some type of repair offer, you could try and air-wire it over to where the trace was supposed to go if its going to waste anyway?

[John]

can you put it back in the loco and take some pics ???  don't tighten it up .. im curious how this lines up

[rrjim1]

Seen this with the original Digitrax Atlas GP7/9/30/35 boards. I was able to file 3 of them down to make them work. Solution was to use TCS decoders for the rest of my GPs. I see Digitrax finally revised there Atlas GP decoders so they should now fit correctly.   

[mu26aeh]

@John everything lines up the same

Here are shots of boards installed, frames together but not screwed together.

First stock DC board

20151231_135912 by Adam Henry, on Flickr

Next up NCE board

20151231_135834 by Adam Henry, on Flickr

[John]

wow .. that is too wide .. you can try a different brand decoder, or mod the frame ..  might also check a different NCE ..

[mu26aeh]

wow .. that is too wide .. you can try a different brand decoder, or mod the frame ..  might also check a different NCE ..

Part of the problem, I have two different NCE decoders, both have same issue.  Both were bought/acquired at two different locations, though I imagine they are possibly from same run/time frame of production.  And this is in two different locomotives, so it's not like the locomotive frame is the issue.

[mu26aeh]

Resolution to this problem from NCE.  Here is reply from them.

"I posed this question to Jim, the owner and chief engineer.
We make OEM boards for Atlas and they were having the same issue.
Bottom line is they have a batch of frames that are different / slightly narrower.

On our last shipment to them they had to mill the frames to
fit the decoders.  Initially they said the new batch of decoders
was too wide, but research (trying to install an old decoder) showed
the new frames are too narrow as compared to their older locomotives.

The problem only lies in the narrow portion of the decoder. While it
is possible to sand the sides of the decoder slightly narrower (just under
.010" from each side) I would recommend filing the frame about that
amount in the offending area."

I filed down board and the frame and had success with one of the locomotives.  Will need to work on the second one more. 

So if you have any Atlas Classic engines that you haven't converted to DCC, you may need to file the frame, board, or both .