Hst 125 lost power and getting hot.

[Lairdy]

Hello there,

I got myself a R3957

LNER, Class 43 HST, The LNER - Farewell Tour™ Train Pack just over a year ago from the hornby shop.

when running it I soon realised that if I say put the power to 60 on the controller the train would run fine but after a couple of minutes of running it would then speed up slightly. It’s like it needed a warm up before the motor started working properly.

Its been like this for the last year but just recently it started slowing down and speeding up again without me changing the power on the controller. That happened for a while but now it’s running slow/lost power, there is a smell of burning and the body of the train gets hot.

I took the top off it and touched the motor which is extremely hot.

Its a dc analogue setup on an oval track.

I had put lube on the required parts but this was about 4/5 months ago.

It pulls 3 carriages and the dummy train.

Any thoughts?

Cheers

Dave

[96RAF]

Likely to be one pole of the motor gone duff. Pull the motor and/or disconnect the wires to the brushes then carry out a continuity check (ohms) across the brushes as you slowly turn the motor, each pole should give the same reading (ohms). Depending upon the motor installation and any capacitors, etc hanging across the brushes you may be able to do this check with the loco assembled measuring wheel to wheel side to side.

[Lairdy]

@96RAF

Thanks for this.

I should have added that I’m quite hopeless and not very confident with tampering with things.

However, I can get hold of a meter and hopefully I’ll not need to do too much disassembling.

I had a suspicion it was the motor. If that is the case would that mean a new motor?

thanks again

Dave

[Rog RJ]

Could be tight gears or bearings/bushes.

[What About The Bee]

Hi David

Understanding WHY is always a good thing.

96RAF wants you to measure the ohms of resistance for each coil of the motor. Why?

An electric motor produces magnetic energy by the number of windings and density of those windings. To obtain maximum power, a motor manufacturer will make the coils with wire dipped in insulation. This allows the wire to be packed closer together, producing more magnetic energy.

When you measure the resistance of each coil, you are essentially measuring the length of wire by its resistance. If one coil measures a lower resistance, it means a shorter wire.

How could that be? Aren't the wires still the same length? Well, no. A very hot motor will melt that dipped insulating material, causing an electrical short within that coil. The electric energy has a shorter path, and therefore less resistance.

Once the coil is shorted, this is only recoverable via rewinding the motor. This may not be economically feasible or indeed, if the motor is potted in epoxy, complete junk.

Heat is the enemy of motors.

Bee

[Lairdy]

@WATB

thanks for this and very interesting.

It doesn’t sound to good for the train in question!

@Rog

thanks for the reply

[What About The Bee]

David

We will not know until you perform the measurement. It is very possible that the motor got hot without melting insulation.

Bee

[Fishmanoz]

I suggest getting in touch with Customer Support with a view to returning for them to look at. Phone is best.

[Barry-350851]

The motors aren't terribly expensive if it is that.

[Brew Man]

@OP

Given your admission to not being very handy DIYwise I would go with Fishy's suggestion and return it to Hornby who can properly diagnose the problem and carry out a repair.

[Lairdy]

Good morning to you all,

thanks to everyone for their reply’s and advice.

I’m going with the advice to send it back to hornby.

thanks again

Dave

[Lairdy]

Hello,

I got a pleasant surprise in the post today.

the above train returned and fitted with a new motor and fixed free of charge.

result!

10 out of 10 for hornby!

cheers

Dave

[Lairdy]

Should of added I sent it back to hornby.

cheers