robertwm3110 Posted December 23, 2020 Share Posted December 23, 2020 Hi, I am fitting a spare MX644 Zimo chip in a DJH class 14. Sorted out the forward/reverse lighting but how do I get a cab light to work. There are half a dozen Function connections going spare, but which do I connect to. Obviously positive (blue) to the common positive but where does the other go. I randomly tried F3 but no joy. Is this a CV setting issue. I want the cab light separate from the direction lights. Link to post Share on other sites More sharing options...
norman Posted December 24, 2020 Share Posted December 24, 2020 You will need to map your function key to your chosen function output. An easy method is to use DecoderPro. Link to post Share on other sites More sharing options...
Suzie Posted December 24, 2020 Share Posted December 24, 2020 I would expect F1 to do the green wire and F2 to do the purple (or is it brown) wire, but it may be supplied different of course. Link to post Share on other sites More sharing options...
robertwm3110 Posted December 24, 2020 Author Share Posted December 24, 2020 Thanks to both. Not familiar with decoder pro but just googled it, thanks. On the other point, Suzie, if I connect to FI then how is this mapped to the cab unit (NCE procab). Which key is going to make it work? Link to post Share on other sites More sharing options...
RMweb Premium Ray H Posted December 24, 2020 RMweb Premium Share Posted December 24, 2020 Do you know what the function key assignments are on the decoder? Link to post Share on other sites More sharing options...
Suzie Posted December 24, 2020 Share Posted December 24, 2020 I think that F1 on an American command station is likely to be the bell. F2 should be the horn. Link to post Share on other sites More sharing options...
Nigelcliffe Posted December 24, 2020 Share Posted December 24, 2020 3 hours ago, robertwm3110 said: Thanks to both. Not familiar with decoder pro but just googled it, thanks. On the other point, Suzie, if I connect to FI then how is this mapped to the cab unit (NCE procab). Which key is going to make it work? As you've found JMRI/DecoderPro, and owing a NCE system, the connection costs from computer are very low - if you have a PowerPro system, you need a USB-Serial adaptor cable from a computer bits retailer. In your other question about the loco, you need to separate out wiring from function keys. They are independent. I'm slightly concerned about a thread talking about MX644 (which is a MTC-21 pin socket decoder) and decoder wires. Is this really a MX644D or MX644C, or if it has wires something else ? Anyway, step 1: connect your cab light to whichever output on the decoder you wish (there are a lot on the MX644). I'd suggest aiming at the first couple of outputs (Fo1, Fo2, etc.). Because of a mess of the two versions of the MTC-21 pin connection standard, avoid Fo3 and Fo4 until you're more confident about making changes. Then, there are several ways with CV changes in a Zimo decoder to map the function output to any function key of choice. So, if you want the light on F3, that's doable once you've decided which wire/pin its connected to. Link to post Share on other sites More sharing options...
Suzie Posted December 24, 2020 Share Posted December 24, 2020 Yes, it looks like the MX644 has not been produced, only the 21-pin MX644C/D variant. The version with wires is the MX645 based on the PluX 22-pin decoder. Link to post Share on other sites More sharing options...
robertwm3110 Posted December 26, 2020 Author Share Posted December 26, 2020 Thanks again for various comments. Just to be clear, this is a MX644D. The reference to wires is based on the fact that the chip is plugged in to a small 21 pin to wire adapter. These (acquired off ebay for a few quid and very good ) are small adapters on which the chip sits ( i.e. male adapter, female receiver on the chip.) The advantage is that they have 21 slightly larger soldering pads which makes wiring a lot easier and if you screw up the soldering you ruin the adapter on not the chip! This is a DJH LOCO with no previous wiring so its all new from the lights etc. Thanks your advice Nigel, but I have now found the paperwork and its a Youchoos chip....that indicates that AUX3/FA1 is the connection for the light, with F6 on the cab unit to control it. So will try that, but if it doesnt work I’ll be back. But I would still like to be able to know how to remap the function outputs to the cab unit function keys. Link to post Share on other sites More sharing options...
robertwm3110 Posted December 27, 2020 Author Share Posted December 27, 2020 Further to last email am pleased to say it works! Wiring to FA1 enables on/off control of the light (for the cab) via F6 on the cab unit. Always helps when you read the instructions!! Link to post Share on other sites More sharing options...
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