This is a second updated version of the Mikado
conversion using a larger smoke unit.
Also the replacement motor is mounted at the front of the gearbox and uses
a single start worm gear for great low speed performance.
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This
uses a MTH smoke unit mounted to the chassis instead of the boiler shell.
This smoke unit has a larger capacity reservoir and larger fan.
MTH Part # AA-2100002
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There is a small amount of milling done to the steam chest for the smoke
unit clearance
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Here is the mounting bracket for the smoke unit. It is made so the smoke
unit exit hole is derctly under the smoke stack. The drive motor
clearance is close to the smoke unit.
The smoke element needs to be changed to a 30 ohm element.
It is a Mouser part # 594-AC01W30R00J.
I carefully tap off most of the ceramic coating to expose the nichrome
wire.
(Version one used a smoke regulator so the element was not changed.)
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I used a piece of rubber tubing to connect the
smoke unit to the smoke stack. |
The antenna and boiler lighting wiring |
The smoke on off switch has to be relocated.
There was room for it under the Cab,
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Here is the view of the program/run switch and
the relocated smoke on-off switch |
The underside of the chassis and the smoke
switch. |
The NYC and B&O Mikado are the first generation
of this loco and the frame and pilot truck will have to be changed to the
later version. The later frame has a mount for the improved chuff micro
switch and holes for the pilot's electrical pickup wires.
Also note, there is a 2.5 mm flat washer added to the pilot mounting screw
to improve the stability of the truck through turnouts.
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Wiring diagram for version 2. It uses a puffer
board and the receiver feature output supplies both the puffer board and
the smoke element. |
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This is the ERR puffer board that takes the
chuff switch signal and converts it to a fixed length 5 volt pulse for the
smoke fan motor.
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On the left is the original motor and on the right is the replacement
motor. By using the Cruise Light system the flywheel is not needed
saving space.
The motor in this conversion version is mounted in front of the gearbox
and therefore the gearbox does not need extensive modification. |
The replacement motor needs to have the American Models Low Speed worm
gear pressed on.
The shaft has to have some knurling chiseled on to it for an interference
press fit for the worm
Motor:
NICHIBO MD3BN-14280-R/51
Gear:
American Models part # GBWSLS |
 The
motor Bearing is turned down .040"
and 2.5mm wshers are added as spacers
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The left motor mount hole has to be elongated
.011" to allow the motor to be rotated for correct gear clearance. |
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