Rebuilding Märklin DR 03 124 from set 3100 to digital with Märklin mfx conversion set 60921
Updated 15.06.2009
This conversion method has also been used on Märklin 3084, 3310, 3315 and 3319. This means the older variants of the Br 03, 012 and 50.
Märklin 3100-2, DR 03 124
Tender:
The tender body is secured to the tender chassis with four clips. The body
can be removed by carefully bending the sidewalls out where the clips are
located. See red arrows in the picture. The green arrow points to a
small 28 Volt T1 bulb glued to the cabin ceiling.
Decoder:
The decoder is installed in the tender, where the electro-mechanical
reversing unit used to be. The decoder is glued to the bracket for the
reversing unit. The two noise suppressors are glued to the tender floor,
as it is very limited space at the motor cover. A small lamp holder, cut
from a SIL socket, is
also glued to the tender floor. Also here a 28 Volt T1 bulb. The
soldering eye, that was used for the wire from the pick-up shoe, is now used to
distribute the rectified plus form the decoder, the orange wire. One wire
leads to the rear lamp and one to the locomotive. Initially this
locomotive was converted with the conversion set 60901. Later the decoder
was replaced with a mfx decoder from a Märklin mfx conversion set (60921, 60923
or 60924).
Rear light and tender weights:
I also wanted rear light, so two holes were drilled in the center of the indicated lamps.
Light guides from the NoHAB diesel (Märklin spare part number 215230) was glued into position. I did not want
to install light in the top lamp, as this seems to be rather difficult. The U-shaped
weights are very important to keep the proper weight of the tender.
Decoder functions:
f0 = light with directional change, three in front, two rear
f1 = smoke unit
f2 = interior light, driver's cabin, 28 Volt T1 bulb with a 330 Ohm resistor
f3 = shunting speed
f4 = acceleration and braking delay off
Motor:
Installation of the motor itself is very simple. Remove the old motor
and make sure that all the rotating and moving parts are clean and work
perfectly. Install the new motor form the conversion set. Carefully
add one small drop of oil to each end of the rotor. To much oil will harm
the operation of the motor. Before inserting the brushes, check once more
that everything rotates and moves normally. Finally, insert the brushes.
Locomotive wiring:
The orange wire also leads from the distributing point in the tenter to a two-pole connector (like the bulb holder in the
tender) glued to the locomotive chassis in the LH side of the motor. The
brown/green wire for function two (f2) also goes to this connector. The
connector is for the interior light in the drivers cabin. I like the warm
yellow colour from the bulb.
Remove the screw securing the locomotive rods. Carefully bend up the
plastic parts including the brake shoes, by inserting a small screwdriver under
it. Draw the three electric wires forwards under the plastic part.
The wires are: plus (orange), front light (gray) and smoke unit (brown/red).
A bulb holder is pressed into the front lamp holder (Märklin part number
614180), to be able to insulate the
bulb from the locomotive body. The contact tongue under the bulb is cut
off (maybe I replaced the bulb holder to a newer type. I do not remember,
as this conversion started years ago, with a 60901 conversion set).
The purple wires go through a small hole drilled in the locomotive body.
Before the drilling I removed the cabin (plastic part), to avoid any damage to it. The
cabin is secured by a clip and some glue. Be careful!
The Märklin DR 03 124 in the dark:
Exposure details: 15 seconds, f8, 100 mm focal length (135-film equivalent)
My setting of the decoder:
| Decoder settings, 3100-2 | Default | Mine | ||
|---|---|---|---|---|
| Analog settings: | ||||
| Enable analog mode | check | < | ||
| Starting voltage | 7,300 | < | ||
| Maximum voltage | 23,000 | < | ||
| Control settings: | ||||
| Swap directions | uncheck | < | ||
| Max speed, 130 km/h | 255 | 98 | ||
| Min speed | 4,000 | < | ||
| Acc time | 7,000 | 15,750 | ||
| Dec. time | 3,750 | 12,500 | ||
| Forward trim | 1,000 | < | ||
| Reverse trim | 1,000 | < | ||
| Motor settings: | ||||
| Motor PWM-frequency: | ||||
| Low frequency | uncheck | < | ||
| High frequency | check | < | ||
| Load Control | ||||
| Reference parameter | 11,300 | < | ||
| Control parameter K | 60 | < | ||
| Control parameter I | 120 | < | ||
| Control influence | 255 | < | ||
| Special options: | ||||
| Preserve direction | check | < | ||
| Persistent acceleration | uncheck | < | ||
| Persistent speed | check | < | ||
| Persistent functions | check | < | ||
The functions, including the connected Märklin 42751 car set:
| 3100 DR 03 124 | 42751 DR 105 281 | 3100 DR 03 124 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| mfx 60921 |
Light | Interior cars |
Interior baggage |
Interior conduct |
Light rear |
Smoke unit |
Light driver |
Shunting speed |
Acc/ dec | ||
| front | rear | ||||||||||
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 |
 | ||
| f0 | f. | 3 | |||||||||
| r. | 2 | on | |||||||||
| f1 | 6 0 9 6 0 a d r. 4 3 |
on | |||||||||
| f2 | on | ||||||||||
| f3 | on | ||||||||||
| f4 | on | ||||||||||
| f5 | f. | on | |||||||||
| r. | on | ||||||||||
| f6 | f. | on | |||||||||
| r. | on | ||||||||||
| f7 | f. | on | |||||||||
| r. | on | ||||||||||
| f8 | f. | delay off | |||||||||
| r. | delay off | ||||||||||