Problem with extra DCC power

[Out Of Puff1707822593]

Hello everyone, grateful for any help with this. I have a growing setup, but with a core of two oval circuits. I have one power track R8241 which I've shown in the attached photo. I'm interested in placing another one, into one of the loops (labelled 'PUT HERE' on the photo). However when I put in it, the electrics just die and the Select Controller flashes as if a short circuit. I've tried with the A/B wires the other way round and it still happens. Is there something basic I'm missing here? Thanks

[96RAF]

Have a read of this guide https://uk.hornby.com/community/forum/getting-started-sets-and-track-mat-expansion-packs-322713

Although it is aimed at DC with a section on DCC you should consider DCC phasing exactly the same as you would matching DC polarity.

You say you have swapped A-B wires but which ones, at the controller or between those two slide in clips.

A simple way of getting power to the whole layout is by using point power clips - essentially bent staples as mentioned in the guide.

You also say you want to put another power pack (Select?) into circuit.

Edit - I misread power track as power pack, however what follows stands firm. You can have as many power tracks or power clips as you want, just make sure the phasing (polarity) is correct rail to rail loop to loop.

There can only be one DCC controller connected to the track at a time. If you want two throttles then connect one Select to another using a special walkabout cable, however the second Select must not be powered direct, it only connects to the primary Select which connects to the track.

[P-Henny]

Expanding your image I can see that all your points already have DCC point clips fitted. Therefore there should be no need to add any further power feeds from your Select to your layout track. If you have a dead spot in the track then you have a basic track connection issue to resolve. This could either be a dirty or lose track joiner or a poor connection with one or more of your DCC point clips.

With regard the Select going into power shutdown regardless of which way round the wires are connected on the R8201 link wire in your photo. I deduce from that statement that you have not removed the suppression capacitors located inside the R8201 link wire track clips.

The R8201 is designed for DC Analogue use and not DCC. If you insist on using the R8201 on a DCC layout, you need to open the clamshell track clips and remove the capacitors that are inside them. The capacitors pass DCC track current through them, the amount of current leakage can be enough to make a 1 amp powered Select think it is seeing a short circuit.

If the purpose of your post is based upon a requirement to increase the power available to your DCC layout, then replace the Select 1 amp power supply with the Hornby P9300 4 amp power supply. As 96RAF says above, you CAN NOT connect a second DCC controller to your track to provide more power. There can only be one DCC controller connected at the same time.

[Out Of Puff1707822593]

Thank you both, I am beginning to understand this better. I have 4 amps already and a Select controller. My layout is getting quite big and I find my short locos often stutter (even though I haven't detected any actual dead spots). I do try and clean the track and keep the connecters tight. I have a fair number of buffer lights and am wondering how many of these kind of accessories I can add before I have power problems.

To be clear, I wasn't going to add another Select controller per se. I have one controller and then split the power feed coming out through a power distribution module (RKpdu2). I wondered if I could take to two feeds from this module and put both into separate R8241 power tracks? Or is this a no-no too!

Thanks for the heads up on the R820. In your opinion would everything work better without these at all? I don't know how easy it is to take the capacitors out.

[96RAF]

[P-Henny]

I wondered if I could take to two feeds from this module and put both into separate R8241 power tracks? Or is this a no-no too!

 

 

If you were a frequent daily reader of posts on this forum, then you would have seen many posts and threads discussing the benefits and merits of installing a DCC BUS. The concept of a BUS is not too dissimilar from your proposal to T more than one connection to the track from your Select. So no, this idea is not a no no. It is just that your R8241 method idea is not necessarily the most efficient & robust way of distributing power on a DCC layout.

Short locos, by their very nature tend to have a minimal number of pickups, so stuttering and similar operational issues are common. These type of issues are usually a function of the wheel and pickup arrangements of short wheelbase locos and rarely fixed by adding extra track power feeds from the controller. The most optimum solution for short wheelbase DCC locos is to add a 'stay or keep alive' capacitor to the loco's decoder installation.

[Rog RJ]

New point may have the built in short circuit problem?

[5Dublo2]

Expanding your image I can see that all your points already have DCC point clips fitted. Therefore there should be no need to add any further power feeds from your Select to your layout track.

 

 

In principle correct, however in practice if your controller power is one side of your DCC Point Clip and you have too many locos or other items using power on the other side, then so much current can be drawn through the point clip that it gets hot enough to melt into the plastic of the points.

 

 

Due to this problem and also to avoid degradation of power and DCC signal associated with crossing track joiners etc it is recommended to have multiple power connections around larger layouts (which is usually done with a wired bus underneath the layout and droppers up to the rails.)

[5Dublo2]

New point may have the built in short circuit problem?

 

 

There has been at least one batch of standard Hornby Points that have had electrical defects. I suspect there is no way to know if the faulty items are still in the supply chain (either as new or second hand)

 

 

 

 

[Out Of Puff1707822593]

Hi all, thank you, I've had many useful ideas from this thread. Thanks also for the photo of how to remove the capacitors from the power clips and I really like the idea of 'stay alive capacitor'. I know the DCC BUS is optimal, I guess I feel intimidated by the idea of it, knowing very little on electronics.

I hope you don't mind a few extra questions;

• is there a reason why putting 2 x R8241 in setup would cause it to short circuit?
• I guess finding a defective point is just trial and error?
• Is there an easy way to find out if 'stay alive' capacitors will work with my existing decoders (they are fairly old locos from ebay - a class 08 and a GWP pannier tank)?

Much appreciated.

[P-Henny]

In answer to your three supplemental questions.

Q1 There is no reason why using two correctly wired R8241 power tracks would generate a short circuit. The key words in this statement is "correctly wired". You will get a short circuit if one or more of the R8241s are wired with the connecting wires reversed.

Q2 I doubt very much that you have a point with the common Hornby manufacturing short circuit fault. This is because all your points in the photo have DCC point clips fitted. If you had a point with the fault, the DCC point clips would instantly put a permanent short across your Select power feed and you are not reporting this in your posts. In response to this Q I am assuming that ALL your points (including those not in the photo) have DCC point clips fitted.

Not that I believe you have one (faulty point), but there is a detailed FAQ in the 'General Discussion' forum index that explains this point fault and how to test for it.

Q3 All loco decoders are theoretically capable of being fitted with a 'stay alive' capacitor. The only consideration would be the skill of the person fitting them. Decoders that are not factory prepared to have a capacitor fitted require very fine soldering skills and a very steady hand. To see what is involved, I suggest you review the 'Fitting stay alive FAQ (FAQ 2)' located in the DCC FAQ Index sticky.

[RDS]

Before I added a DCC Bus to my layout, I used to have 4 concentric loops with a lot of sidings in the middle, all powered from one power clip in the outer loop and it worked well.

As others have said there is no reason other than a possible faulty point(s) that would cause a Short Circuit..

You obviously need to sort that out first, by swopping points if you have any spare.

What surprises me is when you say you have a growing set up, why are you proposing to put the 2 clips so close to each other. If you are unable to install a DCC Bus, I would suggest that you install the power clips at opposite ends of the layout.

[Out Of Puff1707822593]

@P-Henry; Thank you for such a comprehensive answer, I think I'll find out more about the 'stay alive' capacitors on the thread you reference. Much appreciated.

[Out Of Puff1707822593]

@RDS - Fair point!

[rpjallan]

Don't be afraid of using a DCC bus. It's not that difficult & it will future proof your layout. When I first laid all my track, while I was testing it to make sure there was nothing I needed to change (over quite a long period of time) before I made it more permanent, I was using 4 power clips & also a reverse loop module (another 2 power clips) plus point clips. I never had any short problems. I did however have quite a bit of trouble with track joiners. That made up my mind to install a proper bus.

As far as stay alives go, I have quite a few, mainly on decoders wired for them. It is relatively easy to solder them to Hornby TTS decoders as there are pads to solder to. I have a couple of the old Hornby basic decoders that I can't use anymore so I'm going to use them for soldering practice. I have also just bought a whole lot of components to start making my own stay alives.

[96RAF]

There are some basic things to consider with stay-alives.

1. Does your decoder have on board charging control components, if not you have to build these into your DIY stay-alive.
2. If you buy a commercial stay-alive do you need 2 or 3 wire to suit your decoder.
3. Will a stay-alive affect programming your decoder, if so do you need an in-line switch to take it out of circuit when programming.

Stay-alive although a trade name is the most used generic term like Hoover is to describe all vacuums. Other makes can use different terms, such as current keeper, power pack, power bank, brown out protection, etc.

[Out Of Puff1707822593]

Thanks both. I am still mulling over the DCC bus. And I have contacted my local model shop about the stay-alives so I will have a conversation with them.

Incidentally, I opened up one of the power clips and it had no capacitor inside it!

[RDS]

@Out Of Puff

I have approved your picture and deleted the duplicate copies you had posted. All pictures need to be approved by a Moderator, so there is no need to keep pressing enter.

[P-Henny]

Incidentally, I opened up one of the power clips and it had no capacitor inside it!

 

 

The two solder pads indicate that a capacitor is still or was present and subsequently removed. It is not clear, but the capacitor might possibly be the white oblong object on the left placed under the two phospher bronze bars [see Edit below]. Double check the solder pads and make sure that they are not soldered to anything else other than the bronze bars. 96RAFs photo showed a blue capacitor, but they don't have to be blue. As just said, the solder pads confirm that this clip has had a capacitor at some time in its existence [the Edit below suggests that the capacitor is still present].

Edit: Comparing your photo with the one provided by 96RAF on previous page. The white bar in your photo matches exactly with 96RAFs blue bar (capacitor) in the before removal image.

[Out Of Puff1707822593]

Aha, good detective work thanks, I may try and snip it out!

[Brew Man]

Hornby started positioning the capacitor under the brass bars a while ago, possibly to deter people from removing them and preventing them from charging the significant mark-up on the digital version.

[96RAF]

Hornby started positioning the capacitor under the brass bars a while ago, possibly to deter people from removing them and preventing them from charging the significant mark-up on the digital version.

 

 

That was the strange thing, the digital one with less parts was more expensive than the analogue one with more parts - very odd economics. Watch TT:120 power clips and tracks for similar odd price trending until corrected.

[P-Henny]

Aha, good detective work thanks, I may try and snip it out!

 

 

To be pedantic there is no "may" about it. To be used on DCC, the capacitor (should be in both clips) must be removed.

[Brew Man]

Hornby started positioning the capacitor under the brass bars a while ago, possibly to deter people from removing them and preventing them from charging the significant mark-up on the digital version.

That was the strange thing, the digital one with less parts was more expensive than the analogue one with more parts - very odd economics. Watch TT:120 power clips and tracks for similar odd price trending until corrected.

 

 

Yes, odd indeed. Maybe some people expect to pay more simply because it has 'Digital' or 'DCC' in the title, so Hornby is more than willing to oblige.