Heljan O Gauge Class 27 Diesel with Zimo Sound

Kit: MS990L, YLR603010 Speaker

Heljan's Class 27 is their first to include a DCC socket for an 'XL' type plug-in decoder. This means either a LokSound V5 XL with pins, or Zimo's MS990L. Theoretically this should make DCC and DCC Sound installation a whole lot easier than previous Heljan big diesels.

However, the 'XL' standard for pin-out has been interpreted differently by ESU and Zimo... 3 sides are compatible, but the 4 side has support for servo connections, and these are totally different. This model does not have any servos of course, so the header socket on the board in the model on that side does nothing - not connected to anything at all, so we can simply remove that header.

Thankfully, the plastic header just slides up and off the connectors, so we can simply snip off the 'pins' leaving it a flat area. Our MS990L will simply plug into the remaining pins, though careful alignment is required to make sure they match up - there are more pins on the MS990L than there are on the socket of the model.

Here are a few shots of the model's PCB before removal of the servo pins...

The plastic header socket just slides up and off the contacts, which can then be easily snipped off.

...and after...

Our MS990L now safely in position, we can test motion and lighting. Some tweaking of function keys to outputs is needed to match the physical connections of the model:

• F0F - front headcode
• F0R - rear headcode
• FA1 - rear reds
• FA2 - front reds
• FA3 - front cab
• FA4 - rear cab
• FA5 - engine bay lights
• FA9 - fan

A YLR603010 3W speaker is BlackTack'd to the top of the decoder and all is done!

Please note that these guides are provided as useful resources for you, as-is. YouChoos cannot be held responsible for errors in the information, or for any damage caused to your models or equipment if you choose to follow any of the steps detailed here.