Keep-alive in the current iteration of Atlas gold GP9

[GM50 4164]

Yeah definitely not enough room on the end for a KA-N1.  Are those caps above the speaker on your SD7 in the photo?  If so, what is the manufacturer and part#, and how did you wire them in?  At the same U+ and ground points that you would a KA-N1?

Brian, yes, these 2 caps are just lying on top of the speaker. They are not being used, I just placed them there to show that there was room for them as an option. With these units being so light due to DCC and sound, I would hate for you to mill out the fuel tank area if that wasn't absolutely necessary.

These, I believe, are from Digikey.
https://www.digikey.com/en/products/detail/kyocera-avx/TCN4337M020R0100E/10381493
The plugs that are used on top of the board is the route I used for my U+ connection. They are also from Digikey.
https://www.digikey.com/en/products/detail/jst-sales-america-inc/A04SUR04SUR32W305B/6009370

I wired my KA-N1 in the places Peter posted from his write-up of this motherboard, which can be found here.
https://www.therailwire.net/forum/index.php?topic=58111.0

Cheers!

[bbussey]

I didn't realize the caps were just sitting on top.  Yes, the keep-alive wiring is the same for the RS3 as it is for the SD7.

[nstars]

Yes, adding caps will need more space.  But the LokSound nano is 20mm long, which is the length of the "shelf" on either end of the decoder chassis on most hood diesels.  So why can't you design a board decoder with the equivalent of the Nano at one end, a speaker in an enclosure at the other, and keep alive caps in the middle?  OK maybe thickness (height) is an issue; but the current Atlas GP9 board sort of has this construction, with most of the decoder bits at one end, the speaker at the other, and the middle with some things sticking up but vast ("vast" for N scale, anyway) tracts of open land in the middle (there are some tiny resistors there; move 'em). The height of the JST connectors (if that is what they are - the white plastic bits) isn't less than a typical 220uf tantalum chip cap, and as Peteski points out, there are even smaller options available today to fill in that empty space and end up with 400 - 600uf of capacitance to act as an electrical dropout buffer, if not a true keep alive.

It is certainly within the realm of the doable.  So just do it already.  Or as Peteski notes, AT LEAST give us pads to solder to!

John C.

This is exactly the reason why I started using the Zimo decoders on our European models. The MS518N18 has capacitors on the board (although at a low but still very effective 5V) and pads for additional caps. Sofar I haven’t needed additional caps for smooth running. Pity there US sound files are not yet up to par.

Marc

[rodsup9000]

  I received 6 of these GP 7's to put my WP shells on. Found that I could get 4 of these (digikey)  478-TCN4227M025R0100ECT-ND and still get the shell on.

[reinhardtjh]

  I received 8 of these GP 7's to put my WP shells on. Found that I could get 4 of these (digikey)  478-12410-1-ND and still get the shell on.

Rodney, are you sure about the part number?  This data sheet doesn't look like the caps on your GP-7 to me.
https://www.digikey.com/en/products/detail/kyocera-avx/TCJU157M025R0070E/9645205
https://datasheets.kyocera-avx.com/TCJ.pdf

[rodsup9000]

Rodney, are you sure about the part number?  This data sheet doesn't look like the caps on your GP-7 to me.
https://www.digikey.com/en/products/detail/kyocera-avx/TCJU157M025R0070E/9645205
https://datasheets.kyocera-avx.com/TCJ.pdf

I went back and changed to the right part#.478-TCN4227M025R0100ECT-ND

[bbussey]

Milling the trapezoid off the nose on the frame will clear enough room for a KA-N1. The fuel tank area has enough solid metal available to mill for clearance also, but routing the wires would require milling channels to clear the body shell. Mounting the keep-alive in the nose makes things easier.