DCC controller overload

[idavid27]

Hi everyone. 

I bought the 'Hornby R1125 Somerset Belle DCC' set and added extension packs B,C & D. 

All runs perfectly until I attach the R8201 track link wire, after 5 minutes of running - everytime the DCC Select controller gives the 'overload' warning and the train stops. If the track link is not attached it works perfectly. This is a temporary setup until I install something more permanent.

Thanks for any help,

David

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[Chrissaf]

The R8201 is NOT designed for use on a DCC controlled track. The track clips are DC Analogue and contain 0.1uF suppression capacitors. These capacitors will pass DCC signal current through them because the DCC signal is a bi-polar square wave in the 7Khz to 12Khz frequency range. With two of these 0.1uF capacitors effectively in parallel, twice the amount of the DCC signal is being shunted through them causing the 1 amp controller supply to think that there is a short circuit when this capacitor shunted load is aggregated to the current drawn by the rest of the DCC system and DCC locos. Not only that, but the capacitors in the R8201 link wire kit will be distorting the DCC signal waveform and that can lead to a loss of DCC loco control.

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The R8201 Link Wire kit is included in Track Expansion Pack C to cover the situation where the owner is going to use a SINGLE DC Analogue controller on the twin loop layout. It should NOT be installed when Pack C is being used on a DCC layout.

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On a DCC layout, the function of the R8201 Link wire kit is performed instead by fitting R8232 DCC point clips to all the points.

[96RAF]

If you want to use it for DCC then pop the lid(s) open and snip out the capacitor between the contacts.

Pictures of this elsewhere on the forum just recently.

Rob

[Chrissaf]

As Rob says, the clips can easily be modified for DCC compatibility, but as I too indicated, if you use the R8232 point clips you don't actually need the R8201.

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Here is the picture post Rob mentioned (posted in response to a different topic question).

https://www.hornby.com/uk-en/forum/reading-writing-cvs-dapol-loco/?p=1

[idavid27]

That's great thank you for your help, my mistake. Really appreciate your help with this as I was getting very confused about the whole thing. I shall be purchasing some R8232 clips this afternoon!

[idavid27]

Ok so I fitted the R8232 clips to all of the points and removed the track link - after 5 minutes of 2 trains running on different tracks I'm getting 'overload' on the controller again. Amazon sent me a replacement set and with a different controller/trains it still overloads.

The only thing I haven't replaced is the track - since I'm using extensions A,B,C&D.

[Chrissaf]

The Select comes with only a 1 amp power supply. This can limit the number of DCC powered things that you can power up simultaneously. In theory, the Select 1 amp power supply should be able to handle 2 or 3 locos with ease. But that is dependant upon the specifications of the individual locos in question. The Hornby 4 amp P9300 Power Supply is a direct replacement upgrade power supply for the one shipped with the Select controller.

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However, there is a caveat. Normally when using the 1 amp supply with the Select. An OL display on the Select is then normally an indication of a 'short circuit' condition. So I suggest that first you run each loco individually for an extended period of time to see if one or other of them still generates a Select OL error display (it may be that one of the locos has got an intermittent 'short circuit' fault that only shows when the loco has warmed up).

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If however, the only way to see the OL display error is to run both locos together. Try running both at a fairly low speed (this consumes less power from the controller). If there is no OL display at slow speed, increase the speed in steps and monitor. If the OL display then only appears when both locos are running together and at a reasonably fast pace. Then that would tend to indicate that the 1 amp supply is not enough power.

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What were the results of the different diagnostic running tests documented above?

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Do you have any coaches with lighting? Coach lighting will be taking power from the track.

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Does the OL error display coincide with when a train (loco plus rolling stock) is crossing over a point? If the OL error ONLY occurs when traversing a particular point OR a particular piece of track. Then that track location may be being shorted by the rolling stock wheels.

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Does the OL display coincide with changing a point? It has been known for faulty Hornby points that generate shorts when switched to leave the factory.

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...after 5 minutes of 2 trains running on different tracks.

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The Somerset Belle set comes with one loco - a Steam tank engine. What are the other locos you are running? Model R numbers would be preferred.

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The only thing I haven't replaced is the track - since I'm using extensions A,B,C&D.

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Track doesn't consume power (barring losses due to poor joints) it is passive. Track will only generate an OL error if there is a short on it. Hence my questions above about point throwing and OL error locations on the track.

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All my questions are designed to help diagnose your issue, so do please try and spend the time to give full detailed answers to ALL the questions. We don't have the benefit of looking over your shoulder, so we can only work on the answers you give the forum membership.

[idavid27]

Thanks Chris for the detailed reply, my track is in bits tonight as I'm painting the baseboard. Before I did that though I tested the locos one at a time which gave some interesting results. These tests were done one after another without a break inbetween. The other loco is a brand new R3504TTS.

 

• Somerset Belle - overload after 8 minutes occured at full power after building up speed over first minute.
• DB Schenker - overload after 4 minutes at full power
• Somerset Belle - overload after 30 seconds at low power
• DB Schenker - no overload after 2 hours at full power
• Somerset Belle - overload when slowing down after 1 hour at full power

This isn't a complete answer as I'll post more detail when the track is back together. None of the trains have lightning, the DB has TTS sound - both DCC fitted as standard. All overloads happened in different areas of track.

 

 

 

[Chrissaf]

I await further test results, but I can't detect a pattern that makes any sense in the results so far.

[Chrissaf]

After a nights sleep and a time for reflection, here is my initial analysis.

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Caveat.

I do assume here that during your running tests, the loco not being tested was NOT sitting on the track. If the idle loco was sitting on the track then my analysis below is invalid.

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If you did leave the other loco on the track, then redo the tests again, but this time only have the loco being tested on the track.

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Analysis.

Now given that both locos are affected and that each was only run one at time. Then your issue would not appear to be a loco specific issue. That is to say a loco creating a 'short circuit'. Hence my caveat statement above, because a faulty loco sitting on the track can still create a short even if not moving.

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So if it proves that it is not a loco fault, then there is a fault somewhere in the DCC signal path between the Select controller and the loco. Logic would say that this must be an intermittent 'short circuit' fault. Now you have already stated that Amazon replaced the set and you have the same issue using the Amazon replacement Select controller. This would seem to eliminate the Select controller from being a suspect.

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When you connected up the replacement Select controller, did you use the new supplied track power clip and track power wires or use your original ones. If you used the new replacement ones, then they too can possibly be eliminated from being suspect....see comment about Hornby product batch faults below.

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If you used the original power connection components. Then it has not been unknown for Hornby to ship a DC Analogue power clip in the train-set box by mistake instead of the proper DCC one. So referring to the link I posted in my second reply above, open the power clip and look for the DC Analogue component. I would do this anyway, even if you used the new replacement power connection parts, as Amazon may have a complete batch of affected train-sets. If you do find the power clip / power track has this extra component inside, cut it out. On a power track, the removable cover is between the two rails.

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OK, if so far everything checks out. Move on to the track itself. Fortunately you have said that you have taken your track apart, so that means it is not yet pinned down. That makes these next suggestions a lot more easier to follow.

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Logically, there is no way that a basic track piece i.e a straight or a curve can in itself generate a 'short'. That leaves the points. Hornby points have been known to leave the factory with intermittent 'short circuit' faults. Since you have got the basic set oval plus Expansion Packs A through to D. I know that you should have a total of four points.

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Start by building one basic oval using only straights and curves with NO POINTS FITTED.

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Run your locos again, one at a time. If one of the points is indeed faulty then one would then expect the locos to run without issue, as no points are present in circuit.

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If this test is passed, take two of the four points and create a cross-over between two basic ovals (no sidings at this time, just two basic ovals of track with the cross-over between them).

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Run your loco tests again, initially one loco at a time, but then if still no faults have been indicated, run both locos together.

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If this test passed, then replace the two cross-over points with the other pair of points and run the tests again. If the tests failed with the first set of points, but passed with the second pair of points (or visa versa) then that would narrow the issue down to being one point of the appropriate pair being faulty.

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To test each point of the suspect pair individually, create a single oval with one single siding. Now test locos again with each point in turn to see if the fault can be narrowed down to a particular point. There is always a possibility that each point in a siding configuration works, even if faulty, as it is the two oval cross-over point configuration that is more likely to show up a faulty point.

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If every single test above is passed without issue, then I can only assume that there must have been a bit of metal debris on the original track that has now been dislodged during the tear down and rebuild. Or if one of the points did have an intermittent short circuit fault, that the prodding & poking and the pulling & pushing, handling of it has effected a longer term repair.

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Hope this helps.

[idavid27]

Thanks again Chris, will post the test results this evening

[Chrissaf]

If the tests do narrow down the options to the possibility of a faulty point. The Hornby point short circuit issue is usually located on the underside of the point in the frog area. The fault occurs where two metallic rail paths cross over each other for the purpose of extending the continuity of the rails that form the lead in and lead out of the frog section of the point. These cross-over metallic paths should be insulated from one other. The insulation may have been dislodged or damaged in some way. Anyway, this is the area of the point that needs close scrutiny.

[idavid27]

So whilst the baseboard was inbetween coats (don't worry it's dry) I decided to test things out. I had a think about things and the fact I had tried two different controllers which resulted in the same problems. It suddenly occured to me the only thing I hadn't swapped over was the AC adapter - I'd simply plugged the new controller into the current AC adapter. I grabbed the new AC adapter out of the box and since then I haven't had an overload - I've even pushed the limits by trying 3 trains at once with buffer/signalling lights, I couldn't get it to overload even after 3 hours of running. Since I'm planning to add more to the track I've ordered the P9300 anyway.

Massive thank you to Chris for all your efforts and *touch wood* a faulty AC adapter appears to have been the problem.

 

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[Chrissaf]

Strangely enough, and I am not fibbing here. If your results of my last batch of diagnostic tests had shown that the two locos still exhibited issues (individually) when just on a single basic oval without points fitted. Then that was going to be my next question. Did you use the new power pack as well as the replacement Select controller?

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I would point out that in my third reply I suggested that it might be a 1amp power supply not providing enough current.

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You were lucky that you still had the replacement power supply that Amazon sent you. You might have sent the good power supply back as part of the return product process.

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Lesson to be learnt here......when getting a replacement product....change out ALL the parts with the new ones.

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Glad to hear that is now all sorted. I'm sure that you have learnt a lot, going through the fault finding process.

[96RAF]

These PSUs do vary.

 

I was testing ultimate cutout of a Select and with my 1-amp PSU I had 5 TTS locos on track and 2 running gently without problem, so the PSU volts drop protection seemed too high.

 

To get the Select to OL with the 4-amp unit I had 6 locos spinning their wheels up against a barrier (3 loops with 3 locos pushing one side of a bit of wood across the tracks and 3 locos pushing from the other side. It was a simple case of running yet another loco against this ‘wall’ until the power supply cried enough.

 

I would recommend checking your power supply using the coin test to make sure it will protect if you ever need it to. Too late finding out you have a faulty unit by way of smoke from a loco or layout wiring.

Rob

[idavid27]

Lesson learnt and thanks for all your help Chris, if I have any further problems I will use your diagnostic tricks in the future. 

 

Thanks Rob - is the coin test just laying a coin over both rails? Sorry I'm completely new to all this.

[Rog RJ]

No, don't just lay the coin on the track.  Hold it firmly so that it makes a good contact.  You can use anything conductive to make the test, such as a screwdriver, spanner, piece of wire etc.  It doesn't have to be a coin.