North Bridge

It's actually in the PSX manual, Alan, where it describes what each jumper does:

 

J7-1 and J7-2 are the auto/manual reset input. If the connections are open, the breaker will automatically

try to reset every two seconds. If the terminals are connected together (like a SPST toggle switch or a N/C

push button switch), then the breaker will remain off after a short until the connection from J7-1 to J7-2 is

momentarily opened.

 

So linking the two connections together provides a manual rather than an automatic reset.

 

 

Hi folks,

 

Much of interest appears to have come out of my original enquiry! I've beefed up the wiring as suggested and that seems to have cured the problems originally outlined (i.e. NCE Power Cab not fully detecting short circuits). Thanks for all the really helpful suggestions.

 

I also installed a PSX-1 circiut breaker and it is here I've come across another problem. Installed as it came (i.e. with no jumpers) it worked fine - i.e. power cut off when short occurred and then re-connected 2 seconds later. I decided to wire in the manual reset option by connecting a push-to-break switch across J7-1 and J7-2 as per the instructions. It is here that a problem has occurred. To test the effect, first I soldered 2 wires to J7-1 and J7-2 of the board. I held the other ends of these together and then created a short (coin across the rails). The power output LED went out and the short detected LED D6 came on - all as it should. When I separated the 2 wires, the power was also reset as it should. I also tested my switch to ensure it was of the push to break variety (that's OK).

 

I then wired in the switch itself. When a short was created, power was cut off OK (i.e. LED D6 illuminated). However, when the swith was pressed (i.e. circuit across J7-1 and J7-2 now open), LED D6 stays on (and power output LED off)! The only way I can cancel the short is to disconnect mains power and turn on at the mains again. I've since disconnected the push to make switch - in effect restoring the factory configuration, and still, when a short occurs (i.e. J7-1 to J7-2 should be open), power does not restore after 2 seconds - D6 just stays on all the time. Clearly, things are not now working as they should.....

 

I tried re-setting all CVs to factory values (i.e. CV63 to 42) and the problem still persists (though there doesn't appear to be a CV controlling this function anyway - just trying to exclude all potential causes). Can anyone offer any suggestions? I can't see that I've done anything incorrectly - is it possible that my PSX-1 may have a fault?

 

Many thanks in anticipation.

 

Karl Crowther

You never mentioned 'D connectors'!

 

I always, as a rule of thumb, allowed 0.1Ohms per connector in a circuit. (0.1 to 4 amp range, resistive load.)

Each change of wire/contact in the circuit – I refer you to my earlier list – would also add 0.1Ohms.

It all adds up, and what you are looking for is the “straw” that breaks the circuit breakers back!

 

'D' connectors may quote a 5Amp rating but this does not, in any way, make assurances for how the end application WILL be affected by inserting a male/female connector pair.

 

How many pins does your 'bus' use through the 'D' types. Try doubling up, or even, quadrupling up each side of the 'bus' through the 'D' connector.

 

Glad your making progress and to see the the NCE Power CAB is standing up to all the abuse!

 

 

Kev.

(Errr you havn't just twisted any wires together have you? No, thought not. Just remember Camels and straws!)

Hi Kev,

 

Just the one connection for each wire of the bus through D connector (all soldered connections!). I did wonder if doubling up might help, so that answers that question, thanks. In a way, this is what I did when I made an additional (temporary), direct connection of the bus wires across the 2 boards (which seemed to do the trick as mentioned in my most recent post).

 

I think I've identified two further issues with the point crossing/polarity wiring. After looking at my stock of wire, I may have used something like 8/0.2 and not 16/0.2, so perhaps this wire is inadequate. Also, two of the points are split across the baseboard join. This means that the wire from the switch takes quite a lengthy/circuitous route to the Tortoise - i.e. via the between board D connector and its associated wiring loom. Have ordered some 16/0.2 and need to look at ways I can minimise the length of these conenctions as much as possible.

 

Hopefully the PSX-1 that I've just ordered will help set things in order as well, and save my Power cab from further abuse!

 

A photo showing underside of Baseboard 1 is attached, if that's any help.However, note that this was taken before the wiring loom/D connector to the second board had been installed.

 

Thanks once again.

Karl

16/02 will be fine for the droppers and frog connections.

Evening all, Just connected power bus on both boards directly with lighting cable (by-passing D-connector and wiring loom connecting the two - wasn't excessively over-generous in length). Second board now cuts out with coin test on all sections of track (which didn't happen previously). When running 'wrong road' into a point crossing, there's now a very momentary buzz from the power panel and then it cuts out as it should (whereas previoulsy, the buzzing just continued). Don't know if the split second delay will be a problem, but intend to try a separate cut-out as suggested (I gather the PSX-1 is the one to use). That said, one point for some reason still fails to trip the cut-out. Need to turn baseboards over at some point and investigate more fully. Success of sorts and now hopefully have a way forward.

 

Thanks to all, Karl

I know your layout is not large, but I would recommend using at least 1.5mm² wire (15A) and ideally 2.5mm² for the main track bus. The droppers and frog wiring should only be quite short and should not be a problem then - if there is a problem it will show up. There should be no need to double up any of the switch connections if all is well. 

 

If the coin test is failing in places it would indicate that your wiring is marginal and that areas of the layout have a circuit impedance of at least 6R - and it should be possible to measure that with a multimeter to isolate the specific problem area. One big problem with many systems (not sure about the Power cab because I have not seen one) is that the connectors are not quite big enough to get a reasonable sized wire in making getting a good connection to the track output rather difficult.

Hi, Thanks all for further advice. I was wondering if a separate cut-out device would help, something I will look into. I can also foresee an issue with length of wiring from point crossings to Tortoise switch needing to be as short as possible (i've used something like 16/0.2 wire for these connections and all droppers from rails).

 

Having done a bit more checking, I now find that all tracks on the second of the 2 boards produce 'buzzing' with the coin short test, rather than correct shut-down of the Power Cab. This is the 'second' board in that it's the other one that the Power Cab feeds into. Coincidentally, all points are on this second board. On the 'first' board, all tracks cut out correctly with the coin test. Potentially it therefore may be more of an issue of how the 2 boards are wired together (though I think I used the same cable as the main BUS). Best way to test will be to wire the 2 board bus wires together with another, temporary connection, as short as possible, and see if this cures the problem.

 

Thannks to you all

 

Karl

I agree with Suzie. The Loco-on-a-point short has too high a resistance to trip the Short Circuit Protection circuit.

 

But to pinpoint the single area of high resistance may be difficult.

There are many things I don't know about your layout:- size, complexity, wiring design, wiring application, decoders used, Loco wiring, etcetera.

 

Every joint from the output from the controller, the connection to the Bus, the DCC Bus, connections to the track, rail resistance, wheel contact resistance, pickups , internal wiring, electronics, motor windings – and then all the way back again – has a small and usually insignificant resistance.

 

With powerful controllers any short that draws less current than what the controller is capable of will be ignored by the protection circuit. The NCE Power CAB Pro can deliver 5Amps! That is a lot – believe me.

 

As the DCC Boosters get bigger then this problem will become more common.

If this short draws less than the maximum current rating of the controller then adding an external circuit breaker will also not trip!

 

Have you tried putting the 'coin short' on and around the point in question.

(You could also try the 'coin short' trick at the furthest extremity on your layout to see what happens.)

Do you have access to a multi-meter that can measure (accurately) down to 0.01Ohms?

 

 

Kev.

Hi Kev, Susie,

 

Thanks for your suggestions. Funnily enough, after posting I did begin to wonder if it was a wiring issue. I've tested all sections of track on the layout and there are a couple of sections (not on points) where the DCC does not trip with a coin between the rails (I get the buzzing as previously described). This does not seem to correspond with distance from the input (so probably not a straightforward relationship with distance). Each board is 3'6" long and I think the main power bus was 3A multicore lighting wire, with 1A droppers from the rails. I don't know if the main bus could be simply 'doubled up' and more droppers run from point crossings and rails on sections of track that don't trip-out correctly at present (potentially also using both switches in the Tortoise). Or perhaps a complete re-wire using something like 13A cable for the main bus?

 

Thanks

 

Karl

Hello all,

 

I have a query about the short circuit protection for the NCE Power Cab that I am hoping that someone can help me answer.

 

I have tested the short circuit protection by placing a coin across the rails and the power cuts out as one would expect (i.e. there's a 'click' from the power panel and the display on the throttle unit 'flashes' and then re-sets itself). However, something 'strange' happens when a loco approcaches a point set for the wrong route. Clearly, when a loco reaches the crossing (set to the wrong polarity), one would expect a short circuit to result and the system to respond accordingly and shut off power. When this happens in practice, the loco does indeed stop. However, this is accompanied by a loud and quite alarming buzzing sound emanating from the NCE Power Panel. Also, there is no 'flash' on the display screen, which continues to show what was there prior to the short occurring.

 

Apart from the obvious 'panic' on the part of operator when this happens (usual gut reaction is to grab the loco before something awful happens to the chip - not really helpful on an exhibition layout!), I am wondering if this is what should happen?

 

My points are built from C&L components, with the crossing polarity being switched through a Tortoise motor.I asked someone using NCE Power cab about this at a show, and he said the power cut out on his system in the same way as when a coin was placed across the rails - he even kindly demonstrated this to show it was the case.

 

I am wondering if the above affect is something to do with the sensitivity of overload protection circuit on my system, and whether it is possible to adjust it? Can anyone offer any suggestions?

 

Also I am wondering whether an additional circiut breaker is recommended for the basic NCE Power Cab, or whether the in-built one is sufficient? My layout is only 7 feet long and just 2 boards. I know you can get circuit breakers to supply multiple power districts, but I'm happy with just the one supply given the small size of layout.

 

Hope someone can help/advise?

 

Many thanks

 

Karl Crowther

Hi Paul,

 

Thanks for your advice, will try and seek out a copy of the book. Have already been studying photos on your website - what a fantastic resource!

 

Cheers

 

Karl:D

 

Karl

There are NO scale drawings in Dons book, they are BR weight diagrams. Dimensions given are usually accurate (the given dimensions on BR diagram of 4 wheel Flatrol WW is 4 inches out!).

 

An accurate drawing from the wagon was published in

Bartlett, Paul W. & Mann, T., (1984) Cross Channel Ferry Wagons used on BR. Model Railway Constructor Annual 1985 pp 18 - 29, edited by Leigh, Chris. Drawings - BR 20t tank diag. 1/ 304; Lowmac SF diag. 2/254 ; BR 20t ferry van diag. 1/227 .

 

With the risk of being taken to be a terrorist I think the advice to measure one (if you could find one) is not very helpful. B) Lots of photos BR Ferry vans; diagram 1/227 of 1962 and conversions – 36 photographs

http://gallery6801.f...on.php?id=60920

 

Paul Bartlett

Hi Mark,

 

Yes, it would appear that there are a pair at Chinnor. Thanks for the advice. Could always pursue as a last resort.

 

Kind regards

 

Karl

 

If you have a problem with published data them get yourself along to a real example with your tape measure.

 

There are several preserved!

 

Mark Saunders

Hi folks,

 

I am having a go at modelling a standard BR ferry van using the old Hornby model as a basis. I have heard it rumoured that the body moulding on this model is 1mm too narrow. However, I've found a scale drawing of the van in Don Rowland's "British Railways Wagons - the First Half Million" (Leopard - ISBN 0 7529 0378 0).

 

From the dimensions provided in that, I've calculated that the external body width (excluding the doors), should be 30mm (in 4mm scale). The width of the body moulding agrees precisely with that dimension and therefore appears to be spot-on. Can anyone shed any light on the true situation?

 

Thanks

 

Karl:(