MT F7 A-B-B-A DCC & Sound

 

Index:

Overall Configuration

Frame Modifications

DCC Installation

DCC Chip Installation

Adding Caps to DCC

Sound Installation:

DSX Chip Modification

Adding Caps to the DSX

Speaker Modification

Sound Installation

Putting It All Together

 

Overall Configuration

This is the layout I choose to use.  Also note that a similar arrangement can be made by eliminating the speaker in the second A unit to power it, or if one wants an ABA set.

Above is a shot of the consist with the temporary (but running) placement of the components. (Click to enlarge)

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Frame Modifications

The floors need to be cut out for the DSX chip and speaker placement, as well as the metal cones rising out from the frame.  This will also make the units lighter and help them roll more freely (see F7 Rolling Mods section).

A powered unit:

Maybe something for motor wires and lights.

B dummy unit:

The speaker will face down, so we need to cut a path in the frame for the sound to travel through and bounce back up off the track and road bed. The shell will act as a speaker cabinet and enhance the sound.

B dummy unit:

The mangled DSX chip will fit right in here. Note that the securing tabs from the truck frames were cut off to allow more clearance.

A dummy unit:

This frame will mimic the speakered B unit.

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DCC Chip Installation




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DCC Caps to DCC




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DSX Chip Modification

The key to getting sound in the F7s is to modify the DSX chip.

Step 1: Board Prep:

- File the circuit board down as close as possible to the components.

- The newer version of the chip has a cap right along my cut path, so it needs to be moved.  Since de-soldering wouldn't work for me, I took a very sharp exacto knife and carefully sliced it right off the circuit board.  NOTE: Rejumper the cap and test the chip!

- Cut off the 5 pin connector. NOTE: Take caution as the copper traces may peel of the circuit board easily.

Step 2: Board Cut and Clean:

- Cut the board with the sharpest and thinnest blade possible.

- Clean up all the edges and make sure nothing is shorted!  Even the sharpest saw may tear through the thin copper traces and leave dingle berries (burrs).  I lost a chip like this!

- File corners where the chip will be in the fuel tank.

Step 3: Rejumper Connections:

- Solder away! I used as low as heat possible while still making sure the solder joints were solid and shinny.

Step 4: Test With Caution:

- I'm not exaclty sure the proper way to test this.  I blew one up by connecting it straight to the rails while there was a short in it. The next time around, I connected it to the programming track, which can atleast detect shorts.

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Adding Caps to the DSX




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Speaker Modifications

Size comparison of speakers.  Altered speaker is trimmed down on both sides.

The cut sections of the speaker are then filled in with a light wall of silicon to further enclose the speaker cone and stop rattles.

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Sound Installation

Connecting the chip, speakers and caps.

A powered unit:

Run power from the pickups on this unit to the DSX chip.

B dummy unit:

The speaker will face down so that the sound will travel through the cut out port and bounce back up off the track and road bed. The speaker is slightly raised up off the frame so that the cone does not rub against it and cause distortion.  The speaker is also sealed so that the shell will act as a speaker cabinet and enhance the sound.

B dummy unit:

The mangled DSX chip will fit right in here.  Make sure the chip is insulated from the metal frame!

A dummy unit:

This speaker is installed like the other in the B unit.

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Project Conclusions




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