# 55026



## Treeman (Jan 6, 2008)

Working on a Mallet with a six wire interface plug. Have the 55026 cable. Need to connect a 55027. Not positive of the connections. HELP!!


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## Cougar Rock Rail (Jan 2, 2008)

Maybe this will help: 

http://www.ab-treinen.nl/LGB/massoth/lgb-55026-aansluitgegevens.JPG 

Keith


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## krs (Feb 29, 2008)

The Large Scale database has the information I believe. 
http://www.gbdb.info 

Type 55026 into the search field.


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## Treeman (Jan 6, 2008)

Found part of the problem here. The 6 wire interface cable has no connections for track or motors. Seems that this cable could have had the 10 wires needed. These pins are in another location in the loco. Have them now connected to the decoder. One motor the front runs under DCC, the rear does not run. I have exchanged the motor and cable to the motor to prove that they are good. So it seems that the second motor output is not functioning. Any thoughts?


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## mbendebba (Jan 22, 2011)

Hello Mike: 

May be a bad track connection on the second motor?

You should have a total of 12 wires going into the 55027, the six from the 55026, 4 from the front motor (2 track, 2 motor), and 2 from the rear motor ( 2 motor). 


Mohammed 
http://www.allaboutlgb.com


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## Treeman (Jan 6, 2008)

All 8 wires from the 2 motor blocks go to a board in the loco. So I ran the 4 power wires from the decoder to a point on that board marked track and motor. It seems that they should now be all common so both motors should be driven and track power should be coming from both motor blocks.


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## Treeman (Jan 6, 2008)

Just checked continuity from both sets of track power to the common point on the power board. They are indeed connected.


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## mbendebba (Jan 22, 2011)

Mike: 

Have tried running the loco on an analog layout after installing the decoder? if so, did you encounter the same problem? 

Mohammed


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## Treeman (Jan 6, 2008)

Same thing with analog power, one motor running.


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## mbendebba (Jan 22, 2011)

Mike: if both motors are good and the connections between the motor blocks and the main board are good, I would suggest disconnecting the front motor block from the main board and then try reading CV1, or any other CV for that matter, with the rear motor block attached. 

Mohammed


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## mbendebba (Jan 22, 2011)

Mike: 

Were you able to read any CVs? 

mohammed


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## krs (Feb 29, 2008)

Something doesn't make sense here if I read the posts correctly. 

I take it each motor block was tested individually just as a motor block - track pick ups connected directly to motor leads on each block and run on analogue track power to verify that each motor works properly. 

The 55027 decoder only has ONE output for the motors, the motors connect in parallel. 
If both moors work in normal analogue mode (not via the decoder) then either both have to work when connected to the decoder or neither works. There can't be a scenario where one motor works and the other doesn't since they are both connected to the same decoder motor output leads. 
Seems to me there is simply no connection between the decoder motor output leads and the motor block that doesn't run. 

This can't be a decoder programming issue.


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## mbendebba (Jan 22, 2011)

Knut: 
You are right, it is not a programming problem, but it may be a problem with the loco PCB, specifically the connections between the second motor socket on the PCB, and the common motor terminal pins on the PCB. If Mike is unable to read the CVs, those connections need to checked ( actually only those that relate to the motor). If he is able to read the CV, it is back to the drawing board. 

Mohammed 
http://www.allaboutlgb.com 
http://www.massothusa.com


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## krs (Feb 29, 2008)

Mohammed, 

Since Mike already checked continuity from both sets of track power to the common point on the power board with an ohm meter or a continuity tester Ithought it would make sense to do the same thing for the motor connection to the power board. 
I don't know which DCC system Mike is using, there sometimes seem to be odd problems when trying to program or read LGB decoder CV's using some non-LGB DCC systems and I thought sidestepping that possibility would identify the problem quicker. 

Knut


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## Treeman (Jan 6, 2008)

This seems to have nothing with programming. I have not tried to read any CV's. At this point it seems to be a power problem in the main loco board getting power to the rear motor. Don't know what I could be missing here. Just changed all of the switches after wiring in the decoder. Not sure what happens if I change the switches to the original position. Their is no problem with track pick up. I have tested them with an ohm meter. Will check out more in the AM. I have a Massoth system. Should have no problems reading or programing.


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## krs (Feb 29, 2008)

I take it the loco was running fine in "pure" analogue - ie no decoder at all. Both motors were powered then. 

As to the switches, I think all have to be in the opposite position after you install a decoder.


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## Treeman (Jan 6, 2008)

Yes, Both motors were working in analog.


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## krs (Feb 29, 2008)

Not sure which specific LGB Mallet you have, probably doesn't matter much.

This wiring diagran is from "Wiring for DCC" - the power pick-up/decoder/motor connections are very basic.
Maybe it will help you check continuity.
Could be one of the DIP switches don't make proper contact.
But the DIP switches need to be in the "DCC" position or you can fry the decoder


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## mbendebba (Jan 22, 2011)

Knut: 
The problem has nothing to do with track power, I think it has to do with the non-working motor's connections on the PCB. The motor is connected the PCB through a socket, from that socket it is then connected to a set of pins that are shared by both motors. The decoder's motor output is conneted to those pins. I have a feeling that the connection bteween the non-working motor from the socket to the pins is where the problem lies. 

By trying to read CVs with only the non-working motor connected to the PCB, and the decoder connected to the pins, one would be able to determine if there is continuity from the socket to the pins (no continuity, no load, can't read CVs). 

The dip switch must be ok since Mike is able to drive one motor in both analog and digital mode.

Mohammed 
http://www.allaboutlgb.com


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## krs (Feb 29, 2008)

Mohammed, 

I think we are both saying the same thing and Mike understands that as well. 
The reason I asked about running in pure analog is that if it did (and that was confirmed by Mike), then the connections through the PCB and socket and plug etc. must be fine. 
So the problem places I would look for are in areas that change when running digital, like the DIP switch where the power now runs through a different contact than in analogue. 

I have no clue if the wiring diagram I posted actually represents what's in the mallet Mike is converting. 
I think there may be other versions where each motor is connected to a separate DIP switch. 

But all the connections show above need to be there somewhere, so Mike could do some continuity tracing using that diagram. 
Anyway, that's what I would do. 

Knut


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## Treeman (Jan 6, 2008)

I got to the bottom of this with the help of Bob Brashear. He reminded me that these Mallets were made originally to have two 1 Amp decoders installed. So the two motors were isolated. I was installing a single 3 AMP decoder so the two motor leads need to be tied together. Now it makes some sense.


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## rwbrashear (Jan 5, 2008)

Hi Mike, 

For LGB Decoder Interface locomotives, there are DIP switches which isolate power for digital operations. These DIPs switches remove the analog capabilities of the factory delivered locomotive, routing the track power leads and the motor leads to the attached decoder. As you are probably aware, LGB uses the following color code for most locomotives: 
Green/Yellow - Motor leads 
Brown/White - Track leads 

A single motor block locomotive has four DIP switches. 
One switch each for green, yellow, brown, and white wires for the motorblock. 

A dual motorblock locomotive has six DIP switches. 
One pair of switches for paralled brown/white leads. (Brown and white wires from each motorblock are connected in parallel on the locomotive's decoder interface board.) 
One pair of switches for the front motorblock green/yellow leads. 
One pair of switches for the rear motorblock green/yellow leads. 

Please remember, dual motorblock MTS Decoder Interface locomotives were originally designed to accomodate two LGB 55020/55021 decoders (or a single LGB 55020 and an LGB 55030 booster). Since each decoder controls a single motorblock, the green and yellow wires are separate on the locmotive decoder interface circuit board. 

An LGB 55027 decoder is designed to interface with a 'Direct Decoder Interface' style locomotive. The 55027 is still capable of powering a dual motorblock MTS Decoder Interface locomotive, but the green and yellow leads from the decoder must be wired to both male pin connectors on the LGB Decoder Interface board. 

Here is a picture of the wiring harness I typically use for Zimo decoders: 
http://1stclass.mylargescale.com/rwbrashear/DCC/Misc/Completed Dual Motor Block Harness for MX66.JPG 

Best regards, 
Bob


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## Treeman (Jan 6, 2008)

Bob 


As usual you have been very helpful. This was not making much sense until you pointed out that it was intended to use two separate decoders. Now the fix was pretty simple. Thanks for the help.


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## rwbrashear (Jan 5, 2008)

Hello again, 

Here are some pictures of my installation of a Zimo MX-66S into an LGB 22852 Mallet. Please note, space restrictions required the decoder to be hung from the top surface of the boiler. (Some of the pictures may show the decoder in an earlier position which did not allow the boiler shell to be reassembled!) 

http://1stclass.mylargescale.com/rwbrashear/DCC/22852 Mallet Decoder Installation/Dsc00555.jpg 
http://1stclass.mylargescale.com/rwbrashear/DCC/22852 Mallet Decoder Installation/Dsc00556.jpg 
http://1stclass.mylargescale.com/rwbrashear/DCC/22852 Mallet Decoder Installation/Dsc00557.jpg 
http://1stclass.mylargescale.com/rwbrashear/DCC/22852 Mallet Decoder Installation/Dsc00558.jpg 

Please note, I parallel the brown and white wires back to the decoder, too. 

Good luck. 

Best regards, 
Bob


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## rwbrashear (Jan 5, 2008)

Hi Mike, 

I'd post the actual pictures or working links, but the forum software isn't cooperating at the moment. Glad to hear everything is working. 

Best regards, 
Bob


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## mbendebba (Jan 22, 2011)

Hello Bob: 

I looked at the images you posted and discovered that the 2 motorblocks do not share a common set of motor terminal pins on the PCB as I expected and suggested, each motor has it own socket and it own motor terminal pins. The motorblocks had to be connected in paralell to the decoder (this image is worth at lease 999 words, at most a 1000). 

Mohammed 
http://www.allaboutlgb.com 
http://www.massothusa.com


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## rwbrashear (Jan 5, 2008)

Hi Mohammed, 

Exactly! 

The motor pins (green and yellow wires) are not connected in parallel on the circuit board. The electronics for these MTS Decoder Interface locomotives were designed to have two decoders, with one decoder for each motorblock. Newer LGB locomotives are designed to have a single DCC decoder, so the track leads and motor leads for each motorblock are connected in parallel on the DCC Decoder Interface board. 

Best regards, 
Bob


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## Treeman (Jan 6, 2008)

At first I thought this install would be pretty straight forward with the DCC interface. After the initial hook up and one motor not running it was a little confusing until Bob pointed out that the design was for two separate decoders. After that advice it was pretty easy to wire in the second motor. The final problem was a non controlled smoke unit. Again with Bobs input I connected a 24V unit direct to an output on the decoder. Phoenix went in the tender. All is well now. Many thanks to the help here.


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