This can be done on all the models based on the BR V36/236. I have converted the locomotives from the sets 2846, 2848, 28502, the 3145 and the double locomotive 3346.
Updated 22.01.2011
Märklin 28502, RCT 36 274:
Conversion parts:
For the conversion of the 28502 I used the Märklin
conversion set 60921. The old 60901 would also work, so would the even
older 6090. The only difference between the three sets are the decoder;
normal digital decoder in 6090, a digital decoder with extra functions in 60904
and an mfx decoder in 60924. The 60760 set will also work in this
locomotive. This set has a simpler decoder than the other conversion sets.
Decoder:
The decoder is installed at the same place as the original Delta decoder. It is installed in the holder
456200.
The decoder functions:
| Wire colour | function | Connecting to |
|---|---|---|
| Gray | Function f0 forwards | Front (left) lamp |
| Yellow | Function f0 reverse | Rear (right) lamp |
| Brown/red | Function f1 | Relay, light to connected cars |
| Brown/green | Function f2 | Driver's cabin light |
Motor:
Installation of the motor itself is not very difficult, but requires some
mechanical work in the locomotives with two light bulbs. After removing
all the existing parts (motors, delta decoder, bulbs etc.), clean the chassis
and make sure that everything (transmission and wheels etc.) is turning
smoothly.
Before installing the new motor:
The top of the motor cover (brush holder) is a little bit lower than the top
of the magnetic field part of the motor. In the V36 locomotives with two
light bulbs in the centre, the light guide leading to the rear lamps will hit
the magnetic field part, as the magnet wider than the similar part for the old motor.
The four metal plates making this width difference must be filed or grinded
down to the same height as the motor cover to give space for the rear light
guide. It is best to remove the field top from the magnet. It is difficult to
get rid of all the filing dust sticking to the strong magnet. Leave the
magnet on the lower part of the magnetic field, to make sure it is installed the
correct way. If installed the wrong way the motor will rotate the wrong
way. If so, the blue and green wires to the brushes must be swapped.
Hold the magnetic field metal plates tight together with a vice or pliers when
working on them. Otherwise small metal particles may be forced down
between the metal plates, making the part
too thick. Be careful with the guide pins. Be sure that all filing
dust is removed. I normally rinse the part with hot water and dry it carefully.
The modification can be seen in the below photo.
Install the new motor to the locomotive, firstly without the brushes. Check once more that everything revolves freely. Install the brushes.
The motor in 28502:
Lamps:
The original lamps holders in the locomotive is used, now with 610080 bulbs.
The interior light are two 610080 bulbs connected in series. They will
soon be replaced by a LED, see wiring diagram.
A small mono-stable relay is installed for interior light power supply to the connected cars.
Wire connections:
| Wire colour | function | Connecting to |
|---|---|---|
| Red | B (centre contacts) | pick-up shoe connector and relay switch |
| Brown | 0 (tracks) | locomotive ground |
| Blue | Motor brush | rear brush holder |
| Green | Motor brush | front brush holder |
| Orange | Common + | bulbs, in total four (front lamps and interior light) and relay coil |
| Grey | Forward lights | front lamp holder (left hand side) |
| Yellow | Reverse light | rear lamp holder (right hand side) |
| Brown/red | function 1 | relay coil, for power supply to connected cars |
| Brown/green | function 2 | interior light, two 610080 in series |
My setting of the decoder:
| Decoder settings, 28502 | Default | Mine | ||
|---|---|---|---|---|
| Analog settings: | ||||
| Enable analog mode | check | < | ||
| Starting voltage | 7,300 | < | ||
| Maximum voltage | 23,000 | < | ||
| Control settings : | ||||
| Swap directions | uncheck | < | ||
| Max speed | 255 | 77 | ||
| Min speed | 4,000 | < | ||
| Acc time | 7,000 | 10,000 | ||
| Dec. time | 3,750 | 10,000 | ||
| 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 | < | ||
An x-ray shot of my Märklin 28502, RCT 36 274:
The wiring diagram, after replacing the interior light bulbs with a LED:
