Bachmann 9F - Sound decoder, small stay alive and speaker fitting

[Art Dent]

Hi folks,

 

Thought I'd document the fitting of a sound decoder, small stay-alive capacitor and sugar cube speaker into the body of a Bachmann 9F.

 

The process is incredibly easy and could be handled by a relative "novice".

 

First picture shows the loco in question - a weathered version of No. 92220 "Evening Star" from Olivia's Trains.  This loco has much lighter weathering than the first one that Olivia's Trains tried to supply - there was so much weathering you couldn't tell whether the loco was Brunswick Green or black!

 

 

 

Removing the Body

 

There are three screws that need to be removed in order to remove the loco body from the chassis.

 

First, remove the screw retaining the pony truck.

 

 

Then carefully ease the plastic 'loop' off the spigot and then the metal spring.

 

Secondly, remove front screw which retains the body ...

 

 

... and then the rear (either order - doesn't matter).

 

 

You may have to ease the brake rodding apart slightly (they locate into two holes at the end of the chassis and are not glued in place).

 

The body now simply lifts off.

 

 

Location for the Decoder

 

We had originally fitted this loco with a Gaugemaster Omni 27 8-pin decoder.

 

There is space for the decoder to sit in front of the cast weight inside the locomotive.

 

The Omni 27 is around the same size as our intended sound decoder - the Zimo MX645R - although slightly shorter.

 

 

Note - Apply lots of insulation to ensure that the decoder doesn't short on the chassis weight.

 

Helpfully, Bachmann have provided a 'groove' along the top of the chassis weight for cable routing!

 

 

The small wooden block shows the intended location for the sugar cube speaker (a 15 x 10 x 9mm) behind the firebox backplate.

 

This side view shows how the decoder and speaker fit into the profile of the loco.

 

 

Note the insulation tape keeping the spare loop of decoder wire '"safe" from being trapped when the body is replaced.

 

 

Fitting the Sound Decoder, small stay-alive and speaker

 

The Zimo MX645R sound decoder from YouChoos came with the small 470uF stay-alive capacitor already pre-wired to the decoder.

 

A second MX645 (for a different 9F) had only the bare wires soldered to the decoder pcb and the capacitor was 'loose'.

 

 

DO NOT under any circumstances fit the decoder the loco with these bare wires trailing. If they short together they WILL fritz the decoder!

 

Note the black tack on top of the capacitor (a) providing insulation between the capacitor and decoder and (b) securing the decoder in place.

 

Again the excess wire (both speaker wire and decoder wire) can be looped into the groove along the top of the chassis weight.

 

 

Note the black tack (incredibly useful stuff) and insulation tape holding the wiring in place.

 

The speaker supplied by Coastal DCC was a YouChoos 15 x 11 x 9mm 'Flat Top' rated at 1 watt, 6 ohms.

 

 

It fits nicely where our 'dummy' speaker had shown there was space.

 

Body fits on easily and there are just the three screws and pony truck to re-fit.  Most fiddly bit is getting the spring under the pony truck.

 

A quick test on the rolling road (using programming track voltages rather than the full DCC voltages) and she's good to go.

 

Hope this installation helps.

 

Art

 

 

[Art Dent]

Another Bachmann 9F Sound Decoder Installation.

 

Having 'cut my teeth' with the first MX645 sound decoder installation (see above post), I knew what I was doing for loco number 2 ...

 

 

Actually, this was my FIRST attempt at installing the MX645 last year.

 

I had popped the decoder into the socket and put it on my progamming track to test it before fully committing to the install - and all was fine.

 

Having checked that my system could read the CVs OK, I then switched to normal DCC mode and moved the loco.  It went a couple of cm then stopped.

 

There was a smell of 'fried electronics' and an ominous burn mark in the decoder's heat shrink.  Needless to say, the decoder was dead.

 

What had happened was the two speaker wires (which were both bare-ended) had either shorted together on the track or chassis weight and fritzed the decoder.

 

£25 sorted a new decoder out but lesson was learned - NEVER HAVE ANY BARE TRAILING WIRES - ALWAYS ISOLATE & INSULATE THEM!

 

Anyway, back to this (succesful) install ...

 

Last year, I thought that I might have to grind away a bit of the chassis weight so marked up the weight with the length of the decoder with two potential sites.

 

 

In the event, this proved unnecessary.

 

Having said that, if the front part of the chassis weight were ground away (the part marked '30') this would allow the decoder to be positioned on top of the weight and a far larger stay-alive (or even a super-capacitor array) to be mounted where the decoder is currently - i.e. above the decoder socket.

 

I may effect this change sometime in the future.

 

 

The capacitor was black-tacked to the front of the chassis - there is JUST enough room for the 470uF capacitor supplied.

 

 

The decoder sits on top of the capacitor and angled down slightly (otherwise it won't fit in the body)

 

 

Notice in these two pictures how I have added insulation tape to the front of the chassis weight (to prevent shorts)

 

The small 'sugar-cube' speaker locates at the rear of the chassis weight (behind the boiler backplate)

 

 

Re-fit the body making sure all wires aren't in danger of being 'pinched' between the body and chassis.

 

 

All happy and another noisy 9F for our layout!  Just need to add the footplate crew!

 

Art

Edited October 17, 2018 by Art Dent

[Art Dent]

Great use of the space. Thats a really clever idea using the wood as a test to see if the speaker will fit. I can see why you needed to know the depths of my speakers on ebay now!

 

Richard

 

Hi Richard

 

So much easier than looking at the space and guessing that a certain speaker will fit.

 

With the Baccy 9F's it looked like there was space behind the chassis weight and the boiler backplate moulding for a speaker, so I mocked up a sugar cube speaker out of wood to check.

 

I will now look at the space either side of the Dapol 08's body - I already have a Zimo twin speaker in the nose behind the radiator grille - but good as they are, the sound lacks some 'depth' and in the power car of the Hornby Class 43 'Valenta' TTS units (my son has a cunning plan to have TWO power cars - one at each end rather than a power car and a dummy).

 

Results of my investigations will be posted on the forum.

 

Cheers,

 

Art

Edited October 25, 2018 by Art Dent