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Offline Johnvr  
#1 Posted : 01 December 2022 10:47:09(UTC)

South Africa   
Joined: 03/10/2010(UTC)
Posts: 1,254
Location: Cape Town, South Africa

A friend of mine has a Marklin Bigboy locomotive.
It is the earlier version of digital, with dip switches in the first decoder set to address 40, and dip switches for the second decoder set to address 41.
The first decoder runs the motor, and the second decoder operates the loudspeaker for a few sound effects.
It has the older concept of potentiometers for setting the maximum speed and the acceleration and braking delays.
The booklet describes how the locomotive can be operated using a 6021 Control.
It its current state, the Bigboy motor is fine but the sound no longer works.
There is actually one powerful motor which I believe is connected to 2 sets of drivers, each with 4 axles driven.

My friend would like to upgrade this Bigboy to MFX using a MSD3 Sound Decoder, and obviously replace the non-functioning sound module.
I am considering whether the Marklin MSD3 60985 decoder would produce sufficient power to run the Bigboy motor.

My initial conclusion is that the 60985 will produce sufficient power to run the Bigboy motor.
Do you agree with this assessment ?

I note in the 60985 manual that the values of CV 52 can be set as follows :

Motor type ... (Bit 0-4)
... Auxiliary function outputs 5 and 6 0
... Motor – Softdrive Sine 1
... Motor – without feedback control 2
... Motor – High efficiency propulsion C90 3
... Motor – Bell armature 4
... Motor – direct current DC soft 5
... Motor – direct current DC hard 6
... Motor – direct current DC 1 Gauge 7

Selection of a motor type for additional settings for motor feedbackcontrol or
Selection of additional functionoutputs on an H0 decoder.

The Bigboy motor is definitely a DC motor.
Which of the above motor types would be suitable for setting the CV value ?
Do you know what the differences are between these options ?

Offline JohnjeanB  
#2 Posted : 01 December 2022 13:11:10(UTC)

Joined: 04/02/2011(UTC)
Posts: 2,381
Location: Paris, France
Hi John
The motor of the Big Boy is definitely a large DC Bell-shaped armature motor
*** Error correction *** The first Big Boy 37990 is described by Märklin as having a "Bell-shaped armature"
So the choice for the mSD3 is Bell-shaped (CV 52=4)

Next step as you know is the automatic calibration of parameter on a large track loop as per page 30 of the mSD3 manual here https://static.maerklin....bb60f4f6131663855985.pdf

If you cannot reach a good result then try again with DC Hard

Sorry I cannot find any more precise answer but looking into many forums including the Stummi Forum. I cannot find any better definition. To be fair Märklin does not give ANY hint on what is a "DC Weich motor" and a "DC Hard motor"

Edited by user 01 December 2022 21:13:35(UTC)  | Reason: error in motor type at least for 37990 - Sorry -

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Offline bph  
#3 Posted : 01 December 2022 17:05:12(UTC)

Joined: 04/08/2018(UTC)
Posts: 670
upgrading an old Big Boy with msd3 is possible.
if you have an early big boy with a bell armature motor, then try the setting: Bell armature 4. Recommend opening up and checking the motor manufacturer. if it is a bell motor then a decoder calibration is also "required".
one other thing: consider using a relay on the smoke generators, otherwise the decoder might struggle.

you might find some inspiration here: https://www.marklin-users.net/forum/posts/t47323-Marklin-37990-Big-Boy-mSD3-decoder-upgrade

Most likely the problem with no sound is the speaker, it's a common problem, the original speaker in mine also died, and the sound worked "fine" again with a new one. but the old sound decoder is obsolete and it has its own set of issues, especially with the newer cs2/cs3 and in combination with the wheel sensor.

Also, note that depending on the motor some cation might be advised. so recommend that you try to identify the actual motor as there might be variations.

Edited by user 02 December 2022 12:32:04(UTC)  | Reason: Not specified

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Offline Dave Banks  
#4 Posted : 01 December 2022 20:52:45(UTC)
Dave Banks

Joined: 08/03/2006(UTC)
Posts: 973
Location: Gold Coast, Australia.
I used a Loksound V3.5 decoder & relay to power the two Seuthe smoke generators separately for this Big Boy. It was a Trix Loco converted to be the equivalent of Marklin #37992


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Offline Johnvr  
#5 Posted : 05 December 2022 16:48:01(UTC)

South Africa   
Joined: 03/10/2010(UTC)
Posts: 1,254
Location: Cape Town, South Africa
Hi all

Pictures before the conversion starts

IMG_7889 - Copy.JPG

IMG_7890 - Copy.JPG

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Offline bph  
#6 Posted : 05 December 2022 18:36:42(UTC)

Joined: 04/08/2018(UTC)
Posts: 670
note that the locomotive has a wheel sensor for chuffing synchronisation. but you don't need to use it unless it's something you prefer.
if that is something you want to wire up then a 21 pin MTC board is recommended eg the 60975
And you also need to replace the original speaker.
Offline Johnvr  
#7 Posted : 15 December 2022 20:29:54(UTC)

South Africa   
Joined: 03/10/2010(UTC)
Posts: 1,254
Location: Cape Town, South Africa
Hi all

Thanks for all of the comments on the topic.
It gave me the confidence to proceed with the upgrade.

I completed the upgrade and today I completed loading the Bigboy sound files into the decoder.
See results here, running on my Swiss layout :
I am actually delighted with the results BigGrin

Marklin Bigboy upgrade on my layout

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