Odd LGB fault

Graham Hewett

Graham Hewett

Registered
Country flag
About 3 years ago, I bought the LGB Schoellenbahn rack loco produced for the line's centenary. For the first two or so years, it functioned perfectly (running in analogue mode, using standard LGB power supply and control); suddenly, it "decided" to run - quite normally - in one direction only; in the other, it remained stationary, although whenever the power supply was turned up beyond about halfway, the controller shorted out. Before I send it to Maerklin for repair, does anyone have any idea what might be wrong? Loose wire? Defective chip?

Graham H
 
Either a diode, or if it has a decoder in it, then a failed output transistor, I would surmise.. :wondering::nerd:
 
I recently bought a used Schoema diesel in lovely condition that would only run in one direction, after many false starts I removed the circuit board, this has cured it. The board is very spartan, comprising of a couple of diodes, a resistor and a row of switches, the diodes and resistor I assume are for the lights, so that leaves the switches.
What I did notice was that there was no power to the loco lights as well as the motor, couldn’t be the pickups as in the other direction all was well. As I have no need for dcc, it hasn’t been a great loss.
 
Portsladepete said:
I recently bought a used Schoema diesel in lovely condition that would only run in one direction, after many false starts I removed the circuit board, this has cured it. The board is very spartan, comprising of a couple of diodes, a resistor and a row of switches, the diodes and resistor I assume are for the lights, so that leaves the switches.
What I did notice was that there was no power to the loco lights as well as the motor, couldn’t be the pickups as in the other direction all was well. As I have no need for dcc, it hasn’t been a great loss.
Click to expand...
it does sound familiar!.. All I need to do now is pluck up the courage to take it apart. I assume the switches reflect the settings you can choose from the cab, including the on/off switch, which I'd like to retain (like you, not bothered by dcc).
 
My little diesel was extremely easy to take apart, but you would think if a loco is dcc ready it shouldn’t be that difficult, as my loco came fro a start set I believe, it had no switch or cab light, I still don’t know if the switches are to blame, but eventually discounted everything up until the circuit board.
I ended up connecting the motor to the relevant side pick ups, I changed the lights for leds with appropriate resistors etc. I would think your cab switch is all off, no motor but lights, and everything on? If so, it would be reasonably straightforward to connect your switch to retain that facility. Best of luck
 
I concur with Phil. Recommending ripping out the electronics is not what I would do.

Is there any information if this loco is fitted with a decoder?

I cannot think of any situation other than what Phil said that would explain this behavior, no switch setting would cause operation in one direction and a short in the other.

Greg
 
Neither my loco or the Graham’s has a decoder, the board wasn’t ”ripped out”, it was carefully removed.
I must have mysteriously removed a short in one direction presumably, the motor ran perfectly when removed from the loco in both directions, the pick ups on my loco cannot short to anything. More importantly it has worked perfectly for weeks. A true mystery that only be solved by guesswork
 
Getting at the interior and thus the decoder and motor is very simple in this model. Gently pry the running board and full length air cylinder from the left and right sides of the roof. This will expose 6 screws. Take these out and the roof lifts right off. Beware careful of the single lead connecting the pantograph to the circuit board with the switches. Doing this will let you check for something obvious, such as frayed or pinched wires, scorch marks on the circuit boards, etc.
 
Portsladepete said:
Neither my loco or the Graham’s has a decoder, the board wasn’t ”ripped out”, it was carefully removed.
I must have mysteriously removed a short in one direction presumably, the motor ran perfectly when removed from the loco in both directions, the pick ups on my loco cannot short to anything. More importantly it has worked perfectly for weeks. A true mystery that only be solved by guesswork
Click to expand...
Not sure I find that ref to guesswork comforting... But in the light of subsequent posts, will pluck up courage to have the roof off and take a look.
 
phils2um said:
Getting at the interior and thus the decoder and motor is very simple in this model. Gently pry the running board and full length air cylinder from the left and right sides of the roof. This will expose 6 screws. Take these out and the roof lifts right off. Beware careful of the single lead connecting the pantograph to the circuit board with the switches. Doing this will let you check for something obvious, such as frayed or pinched wires, scorch marks on the circuit boards, etc.
Click to expand...
I am most grateful for that advice. presumably, the pan links to the interior wiring in much the same way as the LGB trams?
 
So, maybe I missed something in post #8, here, so "Pete", you know that Graham's loco has no decoder for sure? (I missed this, sorry)

So, what was removed? The main board, or the decoder? I cannot tell from your post.

And Graham, please be assured that the people trying to help you are doing this in a straightforward and deductive manner, without "guesswork"

Regards, Greg
 
Graham Hewett said:
Not sure I find that ref to guesswork comforting... But in the light of subsequent posts, will pluck up courage to have the roof off and take a look.
Click to expand...
Hi Graham, it wasn’t my guesswork I referred to, I found that in one direction there was no power, I tested my loco for open circuit between the wheels/skates and the motor. There is a 4 pin connector to the motor block with wires that go to the circuit board. I tested continuity from those wires to the board from the pick ups and motor, all proved ok. That only left the board, I decided to connect the pick ups to the motor directly, and it worked. With any luck, when you take your body off the connection to the board will be accessible and you could link the pick up wire each side to the relevant side of the motor with a suitable jumper cable after pulling the connector off the board. I just thought my loco fault was similar enough to offer my experience. Whether or not the board had a dry joint or similar, didn’t matter to me as I just wanted the loco to run. Hope this helps
 
Graham Hewett said:
the pan links to the interior wiring in much the same way as the LGB trams?
Click to expand...
If I remember correctly the pan attachment is a single connector that slides over a pin on switch circuit board. It's been about a year since I've been inside my LGB 2146 to change how I wired the lights to the decoder I put in it.
 
Portsladepete said:
Hi Graham, it wasn’t my guesswork I referred to, I found that in one direction there was no power, I tested my loco for open circuit between the wheels/skates and the motor. There is a 4 pin connector to the motor block with wires that go to the circuit board. I tested continuity from those wires to the board from the pick ups and motor, all proved ok. That only left the board, I decided to connect the pick ups to the motor directly, and it worked. With any luck, when you take your body off the connection to the board will be accessible and you could link the pick up wire each side to the relevant side of the motor with a suitable jumper cable after pulling the connector off the board. I just thought my loco fault was similar enough to offer my experience. Whether or not the board had a dry joint or similar, didn’t matter to me as I just wanted the loco to run. Hope this helps
Click to expand...
 
It does sound similar and I will try it (not this week, when i have some storage boxes to make to replace those dreadful TrainLine 45 jobs*...!)

* Recent LGB cartons are hardly better
 
Hi again Graham,

With the roof removed it is vary easy to test the motor in these models. The motor is positioned vertically. This puts both contacts at the top of the motor and they are both connected by wires with spade connectors. All you need to do is unplug both motor connectors and jumper in a dc voltage source. Reversing the +/- will test both directions. This will check not only the motor but also the mechanics of the drive train. You may discover that a mechanical issue is restricting operation to a single direction.
 
You must log in or register to reply here.
Back
Top