Connecting Massoth Electric Uncouplers (Version 2) to Zimo Loco Decoder

[rgsmg53]

Please could one of the DCC experts out there give me some help?

I rather rashley purchased two Massoth Electric Uncouplers (Item No 8442010) thinking they would be two-wire and easily installed and connected to one of the function outputs of a DCC loco decoder (in my case a Zimo MX645). The mechanical installation is not straight forward but that is another story. It's the electrical connections I would like help with, please.

The Massoth printed instructions provided with items state (page 11):

• 1. Black: DEC+ (Decoder +)
• 2. Black: DEC- (Decoder -)
• Brown: amplified function output of the decoder (Open collector, with at least 50mA load capacity at DEC-)

I'm happy with the brown wire connecting to a function output from the decoder (say the brown wire on the Zimo) but where do the other two black wires on the couplers connect to? I believe that they must NOT be connected to left and right rail if I want to use the loco's decoder function wire. So what precisely does "DEC+ (Decoder +)" and "DEC- (Decoder -)" mean? Do I use the "common positive" on the Zimo which is the blue wire and then the "ground" which is the black wire but is already connected to the ground on the stay-alive capacitors? This doesn't seem to make sense as I would have thought that connecting the decoder "ground" and the function wire (negative) in parallel would not be logical.

I'm very reluctant to suck-it-and-see as I could easily write off expensive bits of kit!

Any advice would be gratefully received. I'm probably missing something really obvious.

 

[Diesel2000]

I havent worked with Zimo decoders, but have installed those Massoth auto couplers to an ESU 5 XL decoder. You want to connect the black wires to common positive and ground, just as you suggested, and brown to the function output to be used.

 

[rgsmg53]

Many thanks. Quick response much appreciated. Good to know that was on the right track.

 

[Dan]

I use standard servos with Kadee couplers on my LGB engines and since these are 5 volt units I tie them to ground and plus 5. The programming with the Zimo decoder is somewhat complex as I do use the Zimo 'waltz' as I only have to hit one Function key and the loco backs up, opens the Kadee, stops and then pulls forward all on its own. US cost for 2 servos and a pack of 2 Kadees is $20 US. I use a jewerly chain for the servo to kadee knuckle.