LGB F7

duncan1_9_8_4

Real Ale, Camping It Up, Traveling and the likes.
25 Oct 2009
2,906
452
37
Pontefract, West Yorkshire
Morning. I purchased, off ebay an F7. It works absolutely perfectly on my Dads Massoth Digital set up. But on my set up, CS3 with the Mobile App, occasionally, when bringing the loco to a stand, the leading motor/bogie keeps running while the rear is idle, meaning that the leading motor is trying to drag the back one. It doesn't happen all the time. What could be causing this, any ideas?
 

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PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
27,713
2,864
Tamworth, Staffs.
That is a strange one..
It is the same electronics (even the same output transistor(s) driving both motors,
I would hazard a guess, one motor has been replaced?

Buhler changed the motor - design, some time ago, and the new design is more efficient.
This means that for a loco with two motors, it is possible to have the new one working harder than the older one.
I tend to swap both motors and use the 'good - old' motor, as a spare for a single motored loco.

That is the only thing I can think of.
Anyone, any other thoughts?

If this is the answer, then a new motor in the rear truck, should cure it.
But see if there are any other suggestions, first.

You could try running the loco backwards, and see if you still get the problem?

PhilP.
 

duncan1_9_8_4

Real Ale, Camping It Up, Traveling and the likes.
25 Oct 2009
2,906
452
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Pontefract, West Yorkshire
Thanks, I shall investigate further. Thing is, it does not do it all the time, maybe 1 in every 5 times it comes to a stop. As for going backwards, I haven't noticed it doing anything strange. Just thought it weird that it is ok on a Massoth Setup, and even Analogue.
 

LGB333

Active Member
What DCC sound decoder is installed? I agree with PhilP that the rear motor could be acting up. When converting customers' Analog LGB locomotives with two motors to a DCC sound decoder, I sometimes find during testing that the motors do not operate the same speed. And when I replace the slower motor, it usually then operates out of sync with the other motor, and I end up replacing both motor blocks with new motors, and then they operate in sync speed.

Your CS3 has mfx and dcc technology; Marklin suggests turning off the technology you're not using such as the mfx. Have you had any sound activation issues with LGB locomotives with installed LGB/Marklin mfx/dcc/analog technolgy? I recently tested a customer's LGB RhB Shunting Tractor with one of these sound decoders installed and the automatic couplers were not consistent in their operating and clanking sounds when using DCC. I've ordered a CS3+ Central Station which I'll then be able to use to determine if I encounter the same issue compared to using a DCC Central Station.
 

Dan

Registered
28 Jan 2010
384
34
Eastern MA
LGB does wire both motor blocks in parallel.When one motor runs and the other stops it can only be one of 2 things to look for:
1 Bad motor Swap motors in the blocks to verify
2. Bad connection from circuit board to motor in the motor block

There is etch and solder joint on the board where the 2 motor cables are pluged in, possible cold solder joint
Cable is soldered to connector on top of the motor block.
Motor has 2 brass tabs and these should have a slight twist to make a better connection.
 

duncan1_9_8_4

Real Ale, Camping It Up, Traveling and the likes.
25 Oct 2009
2,906
452
37
Pontefract, West Yorkshire
What DCC sound decoder is installed? I agree with PhilP that the rear motor could be acting up. When converting customers' Analog LGB locomotives with two motors to a DCC sound decoder, I sometimes find during testing that the motors do not operate the same speed. And when I replace the slower motor, it usually then operates out of sync with the other motor, and I end up replacing both motor blocks with new motors, and then they operate in sync speed.

Your CS3 has mfx and dcc technology; Marklin suggests turning off the technology you're not using such as the mfx. Have you had any sound activation issues with LGB locomotives with installed LGB/Marklin mfx/dcc/analog technolgy? I recently tested a customer's LGB RhB Shunting Tractor with one of these sound decoders installed and the automatic couplers were not consistent in their operating and clanking sounds when using DCC. I've ordered a CS3+ Central Station which I'll then be able to use to determine if I encounter the same issue compared to using a DCC Central Station.
I have both types in use. Both MfX and DCC. It just seems strange that it only does it on the CS3 set up. Massoth is fine, as is my little 1amp Analog controller. Had numerous problems with how locos react when controlled by CS3, from speed steps, flashing lights, random sounds triggering. None of which happen with Massoth. Not confident dismantling to look inside, so I think I'll send it to the Model Shop next time i am in York.
 
Last edited:

duncan1_9_8_4

Real Ale, Camping It Up, Traveling and the likes.
25 Oct 2009
2,906
452
37
Pontefract, West Yorkshire
That is a strange one..
It is the same electronics (even the same output transistor(s) driving both motors,
I would hazard a guess, one motor has been replaced?

Buhler changed the motor - design, some time ago, and the new design is more efficient.
This means that for a loco with two motors, it is possible to have the new one working harder than the older one.
I tend to swap both motors and use the 'good - old' motor, as a spare for a single motored loco.

That is the only thing I can think of.
Anyone, any other thoughts?

If this is the answer, then a new motor in the rear truck, should cure it.
But see if there are any other suggestions, first.

You could try running the loco backwards, and see if you still get the problem?

PhilP.
I have had the loco running for an hour backwards, and i cannot get it to have the same problem. Its fine. Then going forward, out of 10 stops, the front motor kept running twice. No problem either direction on my analogue circle.
 

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
27,713
2,864
Tamworth, Staffs.
I am leaning towards it being a motor problem..

IF one has been changed, it could be one of the more efficient ones?
These start running sooner (conversely, run-on, when an older one stops).

The difference could be subtle enough, that analogue DC does not not show the effect, but pulsed power (DCC) does..
A fix, may be as subtle as reducing the start voltage CV by '1'?

PhilP
 

duncan1_9_8_4

Real Ale, Camping It Up, Traveling and the likes.
25 Oct 2009
2,906
452
37
Pontefract, West Yorkshire
I am leaning towards it being a motor problem..

IF one has been changed, it could be one of the more efficient ones?
These start running sooner (conversely, run-on, when an older one stops).

The difference could be subtle enough, that analogue DC does not not show the effect, but pulsed power (DCC) does..
A fix, may be as subtle as reducing the start voltage CV by '1'?

PhilP
What's a CV Never have really understood them. Let alone how to change them on CS3.
 

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
27,713
2,864
Tamworth, Staffs.
What's a CV Never have really understood them. Let alone how to change them on CS3.
A Cofiguration Variable is a way of setting a parameter in a decoder to control 'something'.

In this case, the first voltage the motor gets when you turn your controller up..

PhilP