T class (1st series) by BRM

There are two methods for fitting a speaker in the T class. A bit of a chassis modification enables the use of a large 13x18 mm sugarcube speaker for superior sound. Otherwise if one is unable to perform the chassis mod, a conventional 23 mm round speaker may be used.


Recommended, 13x18 mm sugarcube style speaker:

1) Remove coupler chain pin from coupler box on both ends of model

2) Remove 4 body mount screws and coupler assemblies from underside

3) Wiggle body vertically off chassis

4) Remove 21-pin dummy plug

5) Remove the grey capacitor on top of PCB between two green inductors. The cap will interfere with the decoder's noise suppression circuitry and may cause poor back-EMF control.

6) Using a cut off wheel and Dremel tool, remove a section of chassis, as shown. Be careful not to cut through the long hood lighting wires.



7) Ensure any metal filings from cutting have been removed.

8) Fit the decoder on the 21 pin plug, paying attention to correct mounting orientation

9) Fit the speaker in place

10) Test operation and then reassemble body back on chassis

Conventional, 23mm round speaker:

1) Remove coupler chain pin from coupler box on both ends of model

2) Remove 4 body mount screws and coupler assemblies from underside

3) Wiggle body vertically off chassis

4) Remove 21-pin dummy plug

5) Remove the grey capacitor on top of PCB between two green inductors. The cap will interfere with the decoder's noise suppression circuitry and may cause poor back-EMF control.

6) Insert 21-pin decoder in correct orientation (refer image below) - the fit becomes tight in the final 10% of engagement

7) Insert 23mm speaker in chassis side with speaker front face pointing inboard

8) Use MicroScale Kristal Klear or similar to seal around the perimeter of speaker. This is necessary to deliver maximum sound volume.

9) Test operation and then reassemble body back on chassis.



Important notes:

1) The decoder's 21-pin socket will be a loose fit on the 21 pin male plug. The fit becomes tight during the final 10% of travel.  

2) With body back on chassis, check clearance between motor drive cup and PCB that the decoder attaches to. The two can rub, creating a clicking noise. If it's an issue, poke a jeweller's screwdriver from the underside opening in the chassis and gently create some clearance.

3) If a clicking sound still exists, it may be coming from either drive bogie. The phosphor bronze pickups in the bogies easily move out of position. When they do, they can contact the delrin gears, the interference creating a clicking noise. Remove the bogie sideframes and then unclip the gear covers from the underside of the bogies. Position the pickups away from the gears and reassemble.



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