Further problems with my Standard Class 4 Steam loco

[Bob C]

 

Having now successfully fitted my decoder to my Standard Class 4 Steam loco after help from the forum I was ready to run it. When on the track it starts to run but intermittently it keeps stopping. My Select controller goes into the power up sequence and then off it goes again. I have reduced to a relatively short track and it probably resets about 4 or 5 times on a 5ft by 4ft oval. I have connected a volt meter and I can see the power dissapear from the track when the loco stops. I have managed to place the loco lightly on the track and hold it and the wheels turn freely whithout failure, there is no sign of the drive mechanism fouling. As soon as I let the loco go it moves forward but resets the controller again. Stop/Start.

I have another DCC fitted loco which runs on the track completely uninterrupted so I believe the track is fine. The voltage remains in a healthy state with this loco on. I should add that at this stage I am only trying to run one loco at a time on the track.

I did have a thought to remove the tender (which has the decoder fitted) and power the track from the Select  aux DC output with just the loco on the track as an analogue unit. But I didn't want to do this without confirmation that I wouldn't damage the loco motor. 

If you can offer any assistance I would appreciate it.

Bob C

[Chrissaf]

My Select controller goes into the power up sequence and then off it goes again.

 

It sounds like a classic case of the loco drawing more current than the Select standard 1 amp power supply can supply. The internal 'short circuit' trigger current of the Select is set at about 3.5 amps. This is so the Select can be upgraded to the P9300 4 amp power supply. Therefore, when the Select is used with its standard default 1 amp power supply, it is the power supply that reacts to excess current draw and not the Select internal trigger circuit.

 

The effect of this, is that when the total current draw starts to near 1 amp [the current drawn by the loco PLUS the current used to power the Select itself] then the voltage of the 1 amp power supply starts to drop to compensate and protect itself from damage. This causes the Select to 'reboot'. During the early stage of the Select 'reboot' cycle the track power is switched off. The resultant drop in current consumption due to track power off state then allows the 1 amp supply to auto reset. Then the whole cycle starts all over again.

 

The result of which is that as long as the excess current is being drawn, the Select goes into an endless power up, shut down & reboot sequence.

 

Did you measure the normal running and stall current of the loco before fitting the decoder. It is good practice to do this prior to any decoder fitting to get a starting bench mark figure. Any locos that are drawing high current can be identified and a suitable 'higher current rating decoder' sourced if necessary to prevent decoder damage later.

 

If your loco is just a naturally high current drawing loco and is not drawing a high current due to any faults, then you probably need to upgrade your Select 1 amp power supply to the Hornby P9300 4 amp supply. Your loco may be drawing a high current due to weak motor magnets. Your motor can be refurbished and the magnets remagnatised if a suitable motor type by Scalespeed.

 

The effect of weak magnets drawing much higher than normal currents is extremely well described and demonstrated in this

.

[Bob C]

Thanks Chris, I had a concern that it was overload. This is a recently purchased new loco, just about 3 weeks ago. There are no current ratings in the spec on the website but I did buy it at the same time as the Select. If you are correct I am dissapointed with Hornby if they let me buy products that are not compatible, although it does say in the Select manual that it should be capable of running 3 locos and I am only running one. Maybe it is a faulty loco?

I couldn't run the loco before DCC as I don't have a DC supply and the latest Select, as far as I understand, does not run a loco as analogue. So I have no way of measuring the locos current.

I guess my best course of action is to make contact with Hornby to see what they say. If what you say is correct I will be asking for a replacement or an upgraded Select.

Thanks for your input.

Bob C

[Seacommander]

As your loco is new and fitted with I think a 5 pole can motor I would not expect that the resetting is due to excess current draw by the motor. I would be looking very carefully to try and identify any intermittent short circuits in the wiring both in the tender and locomotive. Also, valve gear if out of alignment is not unknown to cause intermittent shorting especially with metal chassis blocks. Try running the loco when there is no background noise so that any arcing might be heard and give clue to where the problem might be.

[Bob C]

Hello again Chris. I should have mentioned, what do you think about my idea of running the loco as an analogue (by removing the DCC and powering the track from the auxilliary output of the Select controller. Is that viable?

Bob C

[Bob C]

Chris, good suggestion of yours. I think I will remove the body of the train and tender and run it in the dark to see if there is any arcing.

 

Thanks

Bob C

[Chrissaf]

I was assuming that the loco was an old loco with an old style motor, possibly a Ringfield motor or an X03/04 one. If it is indeed a modern CAN motor then motor current draw is probably not an issue.

 

The way that Select analogue mode works does not make measuring current a viable option. The Select analogue mode does not output DC voltage.

 

The Select AUX output is 15 Volts DC whereas the motor is rated at 12 volts DC, so using the AUX output is not a good idea either.

 

As someone that reads pretty much every topic posted [one has to, to fully perform the ComMod role] I have seen many posts of a similar ilk where the fault was with the Select 1 amp supply. It is supposed to be rated at 1 amp, but previous posts have shown that when faulty they can be only good for half that figure. It may be that your 1 amp supply is not able to output the full rated current.

 

The previous posts that highlighted this issue resolved their problems by upgrading the power supply to the P9300 4 amp version.

 

You can add a very cheap analogue motor controller to your tool box, purely for testing purposes, by purchasing a PWM (Pulse Width Modulation) motor controller from China via eBay. A 2 amp controller should be somewhere between £2 and £5 delivered. These just need a 12 volt power input supply. An example is shown below [click the links]:

 

PWM Controller

 

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12 volt PSU

 

Up to you whether you build the China PWM PCB into a case or not.

 

Here is mine I made earlier. The toggle switch is DPDT with centre off for 'Forward - Off - Reverse' switching. Note that the rotary knob on this particular PCB also has an 'on/off' integral switch. The 'centre off' DPDT switch just happened to be in my box of bits.

 

/media/tinymce_upload/30826dc1ca1754c4042ef8cb55610aa8.jpg

[Bob C]

Hi Chris, sorry to be a pain. I have just read up on wheel quartering. Could you have a look at the attached photos of either side of the loco and let me know if you think they are aligned correctly? They don't look right to me and this may explain the problem.

Thanks

Bob C

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[Chrissaf]

I'm no expert on steam, I model modern era. You will have to wait for somebody else to comment.

[96RAF]

Position the wheels on one side so the crank pins are at top dead centre, the pins on the other side should be at exactly 3 or 9 o'clock.

[Bob C]

Hi RAF96, You will have to excuse my ignorance. I am new to model railways and steam trains in general. I have two questions.

What precisely are the crank pins? How do you move the wheels when not on the track to position them?

Regarding the photos above, in the top photo I thought I had what I assumed was the crank pin at 9 o'clock on the centre wheel, therefore I expected the same pin on the top photo to be at 12 o'clock yet it seems to be approx 10 o'clock. hence not properly quarter wheel aligned

As this is a brand new engine I am trying to determine whether I should be sending it back to Hornby for repair or replacement. As mentioned above I have another loco which runs very smoothly on the same track.

 

Regards

Bob C

[St1ngr4y]

Hi Bob,

 

I've drawn some lines on your photos to try to explain it, but I've used the rear wheel in the example.....

 

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/media/tinymce_upload/8f5f8f80fdd30ca18b645ff18ecc561c.jpg

As you have summised, the crank pin attachs the coupling rod to the wheel, and it is the line between the centre of the crank pin and the centre of the wheel itself which concerns us. This (blue) line on the first photo goes from (roughly) NE to SW. I have transposed this blue line to the second photo, but looking at it from the other side of the loco is going NW to SE. The red line shows this angle for the wheel on this side of the loco (roughly) NE to SW, thereby making an angle (roughly) of 90 degrees (quarter of a revolution) where they intersect. I have used the word "roughly" several times in the paragraph above, but I think the angle is near enough to 90 degrees so that it shouldn't cause any problems when the wheels rotate.

 

Ray

[96RAF]

If you use a 9v battery you can touch it briefly to the wheels to get the motor to move the wheels to the 12 o'clock position which simply makes it esier to assess a right angle between sides rther than the angles shown by Ray. Another wy is to remove the body and turn the motor shaft. The anti-reverse mechanics of a worm screw and spur gear preclude being able to move the wheels without power unless by way of turning the motor manually.

 

Depending upon the loco the wheels may be pushed onto splines on the axle or locked in place on a taper by axle end screws or simply by being a push fit on the axle.

 

The aim is to get each side wheels set at an exact right angle to the other. There are such things as quartering jigs but a simple set square will do for alignment.

[Going Spare]

I don't think there is anything wrong with the wheel quartering (and if there was, the loco would run very poorly all the time) but the shaping/positioning of the wire (?) sandpipes is concerning.  If they are wire, they could well be causing short circuits if they link a wheel or a rail with the chassis. Also, it may be a trick of the light but the front coupling rod in the upper photograph looks to be bent inwards towards the wheel.

[ColinB]

What it probably is, is the valve gear. Check that none of it is catching.when the loco goes round corners. I have had it with my Schools Class. What it does, is the crank pin catches on one of the transversing rods (or whatever you call them) and the valve gear locks, locking the wheels making the motor stall, drawing maximum current. Even so, I think a Hornby decoder is only rated at about 0.8 of an amp (it is definitely less than an amp), so if your motor was drawing 1 amp, I would expect the decoder to blow, but perhaps the Select trips before there is any damage. I am sure the stall current on these motors is a lot less than an amp. Unless you have removed the wheels off their axles, I doubt the quartering is wrong especially not on a new loco, Hornby I assume have a special jig in production for setting it properly. Alternatively it could be something else shorting out, even though, from all the bad posts on this forum about the Select, I doubt it is that, because as you say, all your other locos work fine. I don't know how easy this is, but try running it without the front bogie and see it that improves it.

[ColinB]

Having read your post again, I am wondering if it is something wrong with the pickups on the tender. 

[Bob C]

Hello everyone,

First I would like to thank all those that replied. Whilst not directly leading me to the problem I have learnt a lot through reading the replies.

I think, after a lot of inspection, I may have found the problem. I unravelled the wiring loom between the loco and the tender and there is signs of damage to the sleeving. I feel sure there are some bare wires showing. As this is a brand new loco I have sent it back to Hornby for repair or replacement.

Thanks again though for your help.

Bob C

[Bob C]

Hello again,

Just to conclude this post, I have received the loco back from Hornby with the wiring fixed. They also fitted a new motor and decoder (not sure whether the faulty wiring affected these?). It now runs absolutely fine.

Regards

Bob C