Rebuilding Märklin 3772, DB 212 225-7,  to digital with Märklin 60904 conversion set and 60932 mfx sound module

Updated 15.06.2009

Märklin 3772 with the road number 212 225-7 was produced in 1985 and 1986, meant for the Märklin dealer's digital demonstration layout.
Märklin 3757, DB 103 121-0 and 3774, DB 216 127-1, both with transparent body, was also made for this purpose, both from 1985 to 1989.
From 1987 to 1989 the transparent 3772 was made with road number 212 215-8.

Märklin 3772 before modification:

Märklin 3772 after modification, with preliminary close couplers:

The locomotive inside before disassembling:

The locomotive inside after the rebuild:

Conversion parts:
For the conversion of the 3772 I used the Märklin conversion set 60904.  60924 is of course also suitable.  The only different between the two sets are the decoder; normal digital decoder in 60904 and an mfx decoder in 60924.  In this case it did not matter, as I installed the 60932 mfx sound conversion kit.

Motor:
The 3772 has a Large Flat Commutator Motor (LFCM).  Therefore the motor from conversion set 60904 or 60924 is required.

The removed original motor:

The motor installation requires some milling work, as it will not fit in the chassis.  Also the motor itself needs some filing.

First I removed the part indicated by the red rectangle, to fit the thicker magnet.  A small part, under the right red line, had to be removed to give space for the lower motor cover screw.  I did not find the correct color for the repainting.  The new surface after the milling is indicated in red in the below photo.

The bottom of the magnet must be filed off a little bit, to allow free movement of the bogie.  A cut-out must be made (lower arrow) to give space for the bogie part (upper arrow).  Otherwise it will hit the magnet at almost no turning angle.

Newer editions of this locomotive have the Drum Commutator Motor (DCM).  Then the motor from the sets 6090, 60901, 90621 and 60970 will fit.  I do not know what kind of modifications this motor type requires.

Decoder and speaker:
The decoder is installed almost at the same place as the original reversing unit.  It is installed in the holder 456200.  But - only almost.  I did a lot of thinking before coming to the final layout of all the parts.
First I installed the square loudspeaker house, glued to the chassis. I hade to make a small cut at the front lower LH corner of the speaker house, and also a small "step" at the rear end, to fit the motor housing. Next the decoder holder 456200 was glued to the speaker housing. I bent down the front "wall" of the decoder holder.

The decoder functions:
See table below.

Inside the locomotive body there are some reinforcements.  One if these hits the speaker housing, so I had to make a small "cut" on top of  the speaker housing to create space for the body reinforcement.

Some more inside views:
The complete locomotive:

The rear end:

The only thing remaining is to find the correct parts to install close couplers. I have seen some information in an old Märklin Magazine and on some downloadable files from the Märklin website.  And, as this locomotive has a rather advanced and modern propulsion system, I think of replacing the front and rear bulbs with LEDs, three white in the front and to red in the rear.  If so, I will make a printed circuit for the LEDs, something like I did for the Märklin 00380, DB 38 1967.

My setting of the decoder:
Decoder settings, 3772 Default Mine
Analog settings:
    Enable analog mode check <
  Starting voltage 7,300 <
  Maximum voltage 23,000 <
Control settings :
  Swap directions uncheck <
  Max. speed 255 60
  Min. speed 4,000 <
  Acc. time 7,000 11,250
  Dec. time 3,750 11,250
  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 <
Sound settings:
  Volume 255 127
  Driving Sound Rate:
  At min. speed 1,000 <
  At max. speed 1,512 1,576
  Random Sound:
  Min. gap 30 10
  Max. gap 50 <
  Braking Sound Threshold: 14 <

3772 after dark: The image is clickable, 1,75 Mb

My Märklin 3772 DB 63 212 225-7 decoder functions:
mfx
60932
Light Light
intern
Light
intern
Drive
sounds
Flute
long
Flute
short
Horn
high
Horn
low
Shunt
speed
Motor Press.
air
Press.
air
Brake
sound
Acc/
dec
Close
door
Starter
motor
Oil
pump
front rear
f0 f. on                                  
r.   on
f1 f.     on                              
r. on
f2 f.       on                            
r. on
f3 f.         on                          
r. on
f4 f.           on                        
r. on
f5 f.             on                      
r. on
f6 f.               on                    
r. on
f7 f.                 on                  
r. on
f8 f.                   on                
r. on
f9 f.                     on              
r. on
f10 f.                       on            
r. on
f11 f.                         on          
r. on
f12 f.                           off off      
r. off off
f13 f.                               on    
r. on
f14 f.                                 on  
r. on
f15 f.                                   on
r. on
Stop f.                                    
r.                                    
Drive f.                                    
r.                                    

Prototype information:
Road numbers: V 100 2001 - 2381
212 001 - 331
212 342 - 381
213 332 - 341
Number built: 381
Building time: 1962 to 1966
Manufacturers: Maschinenfabrik Kiel (MaK), Krupp,
Henschel, Krauss-Maffei, Jung,
Klöckner-Humboldt-Deutz (KHD)
Axel arrangement: B'B'
Total length: 12.100 mm
12.300 mm from 212 022
Height: 4.250 mm
Width: 3.115 mm
Weight: 63,0 t
Axel weight: 15,8 t
Total wheel base: 8.200 mm
Bogie wheel base: 2.000 mm
Max. speed: 100 km/h (65 in low gear)
Engine type: MB12V652TA, 12 cylinders
Engine power: 993 kW / 1.350 ps
Starting power: 177 kN
Power to weight: 15,8 kW/t
Power transmission: Hydraulic
Heating system: Steam boiler
Safety system: Sifa / Indusi

Some information about the prototype:
http://de.wikipedia.org/wiki/DB_Baureihe_V_100
http://www.studipilot.de/studieninhalte/onlinelexikon/db/DB_Baureihe_V_100/