Kit: MX658N18; Zimo SugarCube speaker; LifeLink; 4x 470uF Tall Tantalums
Bachmann's 2019 J72 model is yet another step forward in design from Bachmann, not only making use of the compact and tidy
Next18 DCC socket, but has on-board SugarCube speaker, and break-out pads on the PCB for connection of lighting and stay-alive.
We found the factory speaker component to be a bit weak, but that is probably down to our expectations - you will most likely
just stick with the supplied speaker (just us pushing the boat out a bit further!)
For this installation we have used an MX658N18 sound decoder, the speaker component from a Zimo SugarCube, YouChoos LifeLink
PCB, and four 470uF 16V Narrow/Tall tantalum capacitors and some self adhesive chrome tape.
This shows the position of the solder pads on the PCB for stay-alive connection...
You could simply plug in the MX658N18 decoder and be done, making it an incredibly simple job to add DCC sound. However, we
decide to make use of the stay-alive pads and to improve the speaker...
We used some craft pins to join the tantalum capacitors to the LifeLink PCB. You can see the kit assembled here. The stay
alive capacitors and LifeLink PCB is exactly the same length as the loco PCB.
Once the decoder was installed the loco was tested on the track. The result was rather disappointing. The sound was weak,
muffled and distorted. This was due to the speaker being clamped up tight to the loco PCB. The speaker needed to have a gap of
at least 1mm from the loco PCB and a better quality speaker used.
We have raised the speaker tabs on the replacement speaker (top arrow).
On the replacement speaker, push this part of the
tab back a little bit so that it can move up and down without catching on the enclosure (top right arrow).
depth of the recess so the speaker enclosure can fit over the ridge in the centre of the chassis and sit flat on the chassis
Remove the existing speaker from the enclosure and remove any sticky from the enclosure that held the speaker in place. Take
the speaker from a ZSCUBE, removing the sticky from the speaker. This will allow the speaker to sit further into the
enclosure. Push the speaker into the enclosure and glue into place.
Glue two layers of 10th plasticard on each side of the enclosure. These small adjustments will create a one millimetre space
between the top of the speaker and the PCB. This will allow the sound to get out and will be much louder and clearer.
The chassis and speaker ready for installation. Also a strip of plasticard wrapped in self-adhesive chrome chrome tape (or
Kapton). Here you can see the speaker is flat on the floor and the gap between the speaker and the loco PCB. Wow the
difference in sound quality and volume is fantastic!
The fire glow is very week and can hardly be seen. The chrome tape will intensify the brilliance of the LEDs.
Photos and instructions kindly provided by Roger Keen of Keen Systems.