Problem with R1041 Mallard - Short-circuit

[Ulrich-1236134]

Hello,

I am Ulrich from Munich/Germany.

Since two weeks I have the Livesteam Set R1041 with the Mallard.

At the one and second attempt the model works very good. But at the third attempt the power unit shut off with a Short-circuit alarm.

I located it on the tender wheels, the right side has contact to the left side. I disconnected the tender from the lokomotive, same problem at the tender.

After disconnecting the wheelunit from the boiler I found the thermistor under the boiler. I disconnected the cables from the wheelunit to the thermistor.

The wheelunit now not have any shortcut. After testing the cables from the thermistor I found the shortcut between the two cables.

I think this is the problem and I need a new thermistor?

Best regards,

Ulrich

[gowest1707822480]

Hi Ulrich

The unit under the boiler is an over temperature device to protect the engine and tender against running out of water and over heating the plastic bodies and other components.

If the control unit sounds an alarm, it is not always a short circuit but may be an open circuit. If you have ever left the engine off the track and switched on the controller after about 5 seconds the alarm will sound.

With the thermostat cold you must have continuity between the 2 wires leading out of the unit the contacts only open when it gets too hot.

Do not just jump to the conclusion that you have a short. These thermostats are very reliable and one my collection of some 30 engines I have never had to replace one.

A fault which can catch you out is the 2 black wires from the engine to the tender, these can break at the tender end and make the alarm sound. Try pulling them to make sure they are soundly connected.

The control unit alarm is sensitive to current. The engine and tender takes 6 amps which is divided by the 2 heaters so the tender heater might take 3 amps and the engines super heater might also take 3 amps if one of thee heaters fails, then the control unit will give an alarm signal.

One way to test which part might be faulty, the engine or the tender, is to switch on the power and see if the volt needle swings over or just past 15 volts. This might mean a faulty heater or Broken wire. If the needle struggles to climb to 9 volts then you have a short circuit.

If you can see it’s the 15 volt end of the scale and the alarm sounds, power off and on till the alarm sounds again. Do this 10 times and at the same time put your hand on the brass tender carefully and see if it’s hot, then do the same to the engine putting your hand on the plastic body. If its cold then the fault will be between the tender and the engine.

Hope this helps, come back if you still have a problem. You can now by spare parts from AC models as they now have all the Hornby parts.

Ken

[BWW1707822948]

Many thanks to Ken for his reply.

I have had this cutout problem and fixed the last one by replacing the cut out unit. However, I have now, some two years later, the problem again but will look and this solution first as it may be that the previous disassembly and reverse was what actually solved the problem. If you have not done can I pass your thoughts to the OO live Steam Club please?

[RDS]

@Barry

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[PlanesTV]

Gowest knows his stuff Ulrich and you sound like you have a good technical ability too.

For those of us with lesser abilities the OO Live Steam Club also hold parts and will repair locos for a fee.

The club website has several videos to help with DIY repairs.

The club is free to join.

[gowest1707822480]

Hope the alarm problem was fixed

how about a live steam one of this engine?

What do you think

[96RAF]

Sounds like a plan Ken but is there room in that low tender for a decent size boiler.

[gowest1707822480]

Hi Rob

space for the water tank will be tight but how about piling the coal up high and building the water tank under it also a more square section would help with a rounded top?

I bought the kit on the internet and it hasn’t turned up yet but it will be interesting to see plus another inside cylinder job if it’s possible to build?

question the engine is in 2 colours does the green have a name or year?

what’s the name of the red brick colour of the frames?

every thing needs some thought yet it might never happen

[96RAF]

Ken

Thomas the tank engine...

Lots of good info here but no real answers to your questions about colour.

https://preservedbritishsteamlocomotives.com/3440-city-of-truro-3440-and-3717/

Plenty of coloured images of 3440 and its mate on-line for reference though.

Rob

[Rog RJ]

Brunswick green ?

[Going Spare]

And Indian Red.

[gowest1707822480]

Hi

thanks for the info on the colours you 2 looks like I must make a note of them

thanks again Ken

[gowest1707822480]

thanks for the info on the colours you 2 looks like I must make a note of them

thanks again Ken

[gowest1707822480]

Hi Ulrich

first the above posts are in the wrong place put it down to old person syndrome

now your problem first the thermistor is not a thermistor but a thermostat it’s job is to keep an eye on the brass boiler temperature that is to say if the boiler runs out of water then over heating will Happen this can impact on the plastic body or burn the soldering

this device will be normally CLOSED so you will get a short circuit reading across the 2 wires if the unit is over heated then an OPEN circuit reading this open circuit will disconnect the power to the engine and tender

This open circuit has an effect on the control unit in as much as if the control unit does not see a draw of 6 amps on its output to the track then the controller will shut down and the buzzer will sound

the parts you have checked out sound to be working correctly you will get what looks like a short circuit across the two wheels sets but might be you just reading the tender heater

Check the wires from the tender to the engine they do break at the tender end so give them a good pull to make sure they are soundly connected.

if you remove the engine body check the heater and the 2 heater wires to the printed board are soldered soundly also the little white plug is soundly soldered

if you have removed the thermostat from the tender black plastic chassis you should on refitting the brass boiler add some white grease on the boiler and thermostat

the controller will sound if switched ON and there is no engine on the track so in the same way if one of the heaters have stop working the same thing will happen as the controller will see a drop in the current to the track as each heater draws about 3 amps each.

try all the above and see if this helps Ken