well sh!t...

[diezmon]

Update on this.  I heard from TCS.  I'd sent the pics of my CB&Q vs the UP unit.  He said, uh . They look the same.  Don't think he looked close.  Then he suggested cutting the board. 

The old installs page is gone,  but I found the PDF version(TCS_Book_of_Classic_N_ Installations.pdf).  Funny, it specifically mentions cutting the front board for a GP20.  No idea why they took the older examples off the site. They're still useful.

[learmoia]

Stupid question.. could you use the LL/MTL SW decoder for short hood installs?  (Installed at the rear).. You'd have to figure out a front headlight though....

~Ian

[diezmon]

Stupid question.. could you use the LL/MTL SW decoder for short hood installs?  (Installed at the rear).. You'd have to figure out a front headlight though....

~Ian

I'm sure it could work. I've hacked similar installs. But then why not just install a small standard decoder.

[learmoia]

I'm sure it could work. I've hacked similar installs. But then why not just install a small standard decoder.

Less milling required for a CN or SW decoder than a standard small..?

[diezmon]

Less milling required for a CN or SW decoder than a standard small..?

good point.  Although, i haven't seen the small decoders lately.  I know there's a Z scale that's pretty dang small. 

[C855B]

Less milling required for a CN or SW decoder than a standard small..?

Maybe. I recall for the GP20 and a couple of Katos I did there was still a bit of milling for wire paths to the motor and clearance around the brush tabs. When the CN fits there is less work to do, but how much less is kinda debatable. The queue of '90s Atlas GP35s and Kato SD40s and 45s on my bench waiting for decoders will attest there's still a big gap in overall effort between the CN and drop-ins for more recent chassis.

There's just enough bench time to install CNs to give me pause in considering the idea of buying replacement chassis from DCC-compatible releases instead. The classic buy vs. make decision, essentially.

[learmoia]

I've been out of the decoder game for a while... Are decoders small enough that we can cut the plastic motor mount above the motor and fit a decoder in there?

~Ian

[C855B]

There are some really tiny ones out now. I think the smallest come from Europe - Zimo MX616 comes to mind, at 8mm square by 2.5mm thick. That is probably not small enough for what you're thinking. I do however think it's small enough to easily fit (in the GP20, maybe others) underneath the front light board, in that area with the window blackout piece.

[diezmon]

There are some really tiny ones out now. I think the smallest come from Europe - Zimo MX616 comes to mind, at 8mm square by 2.5mm thick. That is probably not small enough for what you're thinking. I do however think it's small enough to easily fit (in the GP20, maybe others) underneath the front light board, in that area with the window blackout piece.

You could.  I still think, ultimately, the CN decoders are easier.  You don't have to wire up any lights, if you're ok with the glowing cab look   .  More and more I've been wiring my own SMD leds right into the back of the headlight/number boards, and blacking out the one on the board.  so that's still a bit of screwing around.   The CNs are also easier to replace, should something go wrong.

[peteski]

There are some really tiny ones out now. I think the smallest come from Europe - Zimo MX616 comes to mind, at 8mm square by 2.5mm thick. That is probably not small enough for what you're thinking. I do however think it's small enough to easily fit (in the GP20, maybe others) underneath the front light board, in that area with the window blackout piece.

There currently is a discussion about small decoders in  . . .  the DCC section of this forum. 

https://www.therailwire.net/forum/index.php?topic=48135.0

[robert3985]

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?

(Attachment Link)

First, upon close inspection, it appears the board isn't fully inserted into the former light-board slot.  This may be because the insertion tab on the new board is too long, or there's interference from the metal frame on the face of the former light-board slot. 

Maybe, if you're lucky, making sure the board is fully inserted will give you enough clearance to put the body back on.

However, I have my doubts.

You could cut the frame's metal surrounding the original light-board slot forward opening, and shorten the new board's insertion tab to get it short enough to work, but I think it would be easier to cut the board's sides and the insertion tab end enough to get it to fit...only if there aren't any circuits on the underside of the board.



To get the actual amount of shortening you need, measure how much the original light board protrudes from the slot.

I think this will work without any reversing of the boards or hoping TCS takes care of the problem.

Cheerio!
Bob Gilmore