Taxzilla Posted September 2, 2018 Share Posted September 2, 2018 Hi all. I've been modelling for a while but wanting to take next step and fit sound to a loco. I'll be getting a Bachmann class 37 shortly and I've already bought a Zimo MX644D decoder with stayalive capacitor and a Zimo 3D speaker. I'm confident in fitting the chip to the loco but I'm not sure how/where to attach the capacitor, and also unsure of where to solder the wires to connect the speaker. Also not sure on exactly what type of wire to use. If anyone could be of help it would be greatly appreciated - I could just take it to my local model shop (The signal Box, in Anstey, Leicester) but I'd love to be able to learn how to do this for myself. Cheers! Link to post Share on other sites More sharing options...
RMweb Gold Phil Bullock Posted September 2, 2018 RMweb Gold Share Posted September 2, 2018 If thats a current one it should have speaker connection points on the PCB - probably labelled SP+ and SP- As for the wire - nothing too hefty needed, A fine multi stranded cpooer wire will be fine Phil Link to post Share on other sites More sharing options...
RMweb Premium Izzy Posted September 2, 2018 RMweb Premium Share Posted September 2, 2018 This guide is very useful - http://www.youchoos.co.uk/Index-Detail.php?L1=Detail&Item=MX644 You do need to attach the stay-alve wires before fitting the decoder as they are on the side that faces the PCB. There should be pads on the loco PCB for the speaker wires somewhere. No doubt someone with a 37 will be along with the info/pics to help you. Izzy Link to post Share on other sites More sharing options...
Taxzilla Posted September 2, 2018 Author Share Posted September 2, 2018 If thats a current one it should have speaker connection points on the PCB - probably labelled SP+ and SP- As for the wire - nothing too hefty needed, A fine multi stranded cpooer wire will be fine Phil Thanks for that Phil - much appreciated! It is a current model (MMRG Ltd edition) so I'll look out for those. After wiring speak to the PCB points on the loco I assume its just a case of attaching the capacitor directly to the chip and I'm good to go. Are you able to help with where the wires should be attached to the speaker? (see picture) Cheers, David. Link to post Share on other sites More sharing options...
Taxzilla Posted September 2, 2018 Author Share Posted September 2, 2018 This guide is very useful - http://www.youchoos.co.uk/Index-Detail.php?L1=Detail&Item=MX644 You do need to attach the stay-alve wires before fitting the decoder as they are on the side that faces the PCB. There should be pads on the loco PCB for the speaker wires somewhere. No doubt someone with a 37 will be along with the info/pics to help you. Izzy Thanks Izzy - that's really useful Cheers, David. Link to post Share on other sites More sharing options...
RMweb Premium Izzy Posted September 2, 2018 RMweb Premium Share Posted September 2, 2018 They are nice speakers. I have used them in a J15 and 08. The wires are attached to the spring contacts on either side. I always solder them on. Doesn’t matter which way around the wires go, but as you can see from the YouChoos help/guide it’s absolutely crucial with the stay-alive ones or it all goes pop/bang - along with all you’ve spent! Izzy Link to post Share on other sites More sharing options...
RMweb Premium Izzy Posted September 3, 2018 RMweb Premium Share Posted September 3, 2018 (edited) Meant to add, just in case you aren’t aware, do use a 25v capacitor, it’s the minimum voltage the MX644D’s circuit can use, unlike the MX645D ( which can use 16v). Usually Zimo/Rail Exclusive provide the correct voltage with the sample cap they give. If you use 16v then you must add the standard resistor/diode circuit as per normal. Izzy Edited September 3, 2018 by Izzy Link to post Share on other sites More sharing options...
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