well sh!t...

[diezmon]

Now that I'm (almost) done with this unit, I'm realizing I've never installed a TCS CN-GP in a low short-hood Geep(LL GP20).  Damn thing doesn't fit in the cab.   

After a quick look, I think that front board is also too long for the rear.  The LL GP20 is mentioned specifically in the documentation.   Any GP20 CN-GP experience out there?

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[C855B]

... Any GP20 CN-GP experience out there?

Yes! I did it years ago and it's one of my favorite and most reliable runners! Let me go look for it...

[Insert "Final Jeopardy" tune here.]

 ...OK, found it:



UH OH! The front board is different! You might want to contact TCS tech support and alert them to the issue. Hopefully they can help you out.

Much sadness here as well because I'm in the same boat with two or three unconverted GP20s in the bench queue.

[daniel_leavitt2000]

I have installed one of these on a kit-bashed GP10 which used the LL-Canada GP9 chop nose as a starting point. Not exactly the same chassis as yours, but similar issue.

The logic pc board was designed to be in front, and I think this was a mistake. Rear hoods are always the same size, but front hoods change depending on configuration. I think it would have been smarter to mount the chips in the rear.

And that's eventually what I did. The logic board was installed in back and the lighting board was in installed in front. The lighting board does not feature any important circuits near the chassis mounts and can be filed down by several millimeters to shoehorn it in properly.

Two things you need to be aware of when doing this:
1. Engine and lights will run backwards if all the wires remain the same.
2. Although you can flip the motor wires, the LEDs will still operate backwards when on DC mode. And there are no CVs that can change the DC lighting.

So I eventually kept the original wiring intact so that it would run "backward" on DC This was done to eliminate any potential headaches trying to figure out which wire goes where if I ever take the thing apart again. I just changed the CVs to reverse the motor and lighting effects in DCC and disabled DC operation completely.

Hope this helps.

[diezmon]

Two things you need to be aware of when doing this:
1. Engine and lights will run backwards if all the wires remain the same.
2. Although you can flip the motor wires, the LEDs will still operate backwards when on DC mode. And there are no CVs that can change the DC lighting.

hmm, yeah i figured I'd just flip the boards, then mess with some CVs. [edit] Looks like CVs 49/50 will do it.

[diezmon]

Yes! I did it years ago and it's one of my favorite and most reliable runners! Let me go look for it...

[Insert "Final Jeopardy" tune here.]

 ...OK, found it:



UH OH! The front board is different! You might want to contact TCS tech support and alert them to the issue. Hopefully they can help you out.

Much sadness here as well because I'm in the same boat with two or three unconverted GP20s in the bench queue.

Whoa.. totally different..  I'm pretty sure that longer board won't fit in the back either.

[diezmon]

there's a little room on the contacts end of the board, I may be able to trim a little off.  But, I'll wait to hear back from TCS first. 

[peteski]

I wonder if the longer boards are "new and improved" version, or maybe older version of that decoder?  TCS would know for sure.

[C855B]

I wonder if the longer boards are "new and improved" version, or maybe older version of that decoder?  TCS would know for sure.

Valid question, but I have a strong hunch the answer it's the new one that's longer. I installed mine years ago, within weeks after the CN-GP was first released as the Holy Grail to address the difficult-to-convert large base of '90s-era split-frame diesels. I now had better be careful about which of my older fleet I convert, reserving my stash of older CN-GP for the LL GP20s and maybe even a couple of Atlas GP9s and 35s. The new revision had better darn well fit in older Kato SD40/45s, as I still have a bunch to do.

This is the second time in my recent experience where TCS has been tripped-up on fitment. The latest Atlas C628/C630s from last year don't use the same form factor as earlier releases, and the AMD4 does not fit these. I documented this for them, but still no word on anything from them that fits the new "medium" Atlas frame.

[tehachapifan]

Are you sure the board positions can't be flip-flopped? Doing a rough measurement off the computer screen, it looks like the longer board might extend right to the end of the frame but possibly not past. May have to eliminate any light pipe assembly inside the shell that might interfere, however.

[diezmon]

Are you sure the board positions can't be flip-flopped? Doing a rough measurement off the computer screen, it looks like the longer board might extend right to the end of the frame but possibly not past. May have to eliminate any light pipe assembly inside the shell that might interfere, however.

Not sure, but it looks close. I've emailed support and am curious what they'll say.  I'll check fitment when I get home

[diezmon]

well now.. I measured the boards.  That front board won't fit in the back either.  sheesh.

[EmdFan]

Not sure how helpful this info will be but...

I have a test chassis for the new GP20 sound chassis in front of me. We did not make any changes to the inside of the body or the glazing pieces. The board I have on my desk now measures 2 19/32 total length, and fits fine in the shell. Of course this is a one piece board so it's vastly different than what you are working with. But it does give an overall length measurement that may be helpful?

Either way I would expect a quick reply from TCS, they are usually very good at responding.

Steve

[Burlington Bob]

/>
As long as they didn't change the dimensions of the CN-GP, this should cover what you need to do regarding the trimming of the front board.  I haven't watched this all the way through, but did skim it and he does mention trimming the board.  The old directions TCS had on their website told what needed to be done.  However, they only have directions for the newest version posted now.

When I did mine several years ago, I used a Dremel with a sanding drum and used it to shorten the end of the front board that slides into the mounting tabs on the frame.  Wear safety glasses and a dust mask and grind slowly and carefully and check the fit.  That was the fourth decoder install I had done at the time and the first that I had to solder any wires.  Mine turned out fine and as long as TCS hasn't changed anything, yours should too.

[daniel_leavitt2000]

well now.. I measured the boards.  That front board won't fit in the back either.  sheesh.

It has to. I used that board on the GP9 with the same clearance. I did file down the light pipe but it will work.

[diezmon]

It has to. I used that board on the GP9 with the same clearance. I did file down the light pipe but it will work.

Yeah, it's the light/number board that screws it up. 

But, reversing boards, messing with cvs and cutting light boards is a bit overboard when the manual says it should just fit