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Author Topic: Losing Directional Lights on N Gauge Locos  (Read 460 times)

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Offline Josiebenn

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Losing Directional Lights on N Gauge Locos
« on: August 29, 2017, 11:23:46 am »
Hi All,
I have mentioned this problem before, late 2016/early 2017.   Throughout 2017, the problem has recurred with a Farish 70, and Farish are still, very kindly, puzzling over this for me. Always the same symptom, half of the directional lights stop, (Thats one leading and one trailing as a linked pair) while the other pair keep going, and never any worsening, nor damage to the main motor.

Sadly this month a Kato SBB RE460 also lost its lights, and the dealer showed me blown lamps. He had already replaced a Fleischmann SBB Driver control Passenger Coach which lost its directional lights. 

To summarise Locos that have suffered are a GF 66, a GF70, a Dapol 66, and now the Kato but which lost all of its lights over a period of 2 days and the FL Driver Coach.

I have carried out some tests suggested by Gaugemaster. i.e. Throw each point and check for surges on a multimeter..Done..no spikes.  I threw each point while the room was darkened, looking for sparks from dodgy wiring, no sparks.  The long-installed Ammeter never shows any spikes.  I notice a very slight drop in voltage whenever I throw a point, and I can hear the loco running at the time slightly pause.  I assume this is due to the CDU recharging itself and is normal. 

I've had 2 Combi, and Ive seen lights lost, as I describe, on a brand new replacement GF Class 70 an isolated virgin loop set up for testing with a brand new Combi. 

Any further abstract suggestions on the cause?  Should I/Can I put a mains surge protector before the 16v GM Combi Transofrmer?

Offline Only Me

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Re: Losing Directional Lights on N Gauge Locos
« Reply #1 on: August 29, 2017, 11:32:16 am »
some interesting text above :-

what make is your CDU?
whats powering your CDU?
this circuit should be separate from your controller circuit...
You say the loco hesitates momentarily when you throw points..... that shouldn't happen...

« Last Edit: August 29, 2017, 11:34:41 am by Only Me »



Offline Josiebenn

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Re: Losing Directional Lights on N Gauge Locos
« Reply #2 on: August 29, 2017, 11:40:46 am »
Controller is a GM  Combi.  V Basic. It has 16v connections  for the track and   16v connections for auxiliary, which goes to the CDU.  It is fed by a GM transformer that came with it, which sits on a 13a socket.   

Yes, I can hear the loco decelerate very slightly each point throw, and the ammeter needle momentarily drops a milliamperes or two. 

Offline Only Me

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Re: Losing Directional Lights on N Gauge Locos
« Reply #3 on: August 29, 2017, 01:30:00 pm »
ok, so a combi is rated at 16V 1.1 amp....  if you were to be say running two or maybe three trains at once, it would one would imaging be running at about 600ma.... or half its load capacity.... then you are also trying to run a CDU from it, these usually need 16vdc (or AC!)  minimum at about 3 amps to properly fire a point motor IMO ...  I'd say you are probably overloading your controller when you flip the points as shown by the momentary loco slow down as it all tries to recharge again..... I'm guessing your ammeter is only across the track so you wont see what draw is on the transformer?

A little trick for you is to use an old laptop power supply rated between 19 and 21 VAC for your CDU power...

Can only think that as a point fires it creates a surge some how back onto your track and through a loco.... If you could work out what part on the pcb goes poop it would be easier to work out if its a surge or not..

Horseley Fields uses 3 Combis and we've never had the issue you describe, the only difference being we power the points CDU units from a separate supply.
« Last Edit: August 29, 2017, 01:32:54 pm by Only Me »



Online ntpntpntp

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Re: Losing Directional Lights on N Gauge Locos
« Reply #4 on: August 29, 2017, 02:19:31 pm »
Mostly agree with @Only Me, except I doubt the CDU actually draws 3 amps to charge, there's usually a resistor and they take a second or so to recharge.  Depends on the design of course.  The 3 amps would be the CDU output "burst" to the point motor.

I absolutely agree that it's better to run the CDU off its own power pack (transformer/rectifier).

Are you absolutely sure that the point motor circuit is otherwise totally independent from the track circuit, as it does rather sound like a some sort of spike is getting into your track?

Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline Only Me

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Re: Losing Directional Lights on N Gauge Locos
« Reply #5 on: August 29, 2017, 03:41:36 pm »
ohhh I've had a thought... isn't the earth common on these combis....... that may be your loop to a short...



Offline Josiebenn

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Re: Losing Directional Lights on N Gauge Locos
« Reply #6 on: August 29, 2017, 06:03:47 pm »
Many thanks for your responses.  Bear in mind that I was a complete new starter last September.   I was advised at purchase time that the Combi could run as many points as i wanted from the auxiliary connection.  (Isn't that the purpose of the aux?). So I wired in the CDU, and have 21 points,   but of course I never need to change more than two at any one moment and I wait a moment between the two actions.  Due to the problems I am on my second Combi, granted under warranty. So 2 Combis playing up? Really?!

If I can't find a PC transformer just lying around my place, are there 16v transformers for model,railways that don't involve a controller? 

I am confident that there are no bare metal contacts between the circuits. The CDU is fed from the aux which then runs pos, neg and common earth to a distribution area.  Th bus is fed through the ammeter(pos only of course, neg goes past) from the 16v track connectors.  No possibility of cross contamination. 

Offline Only Me

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Re: Losing Directional Lights on N Gauge Locos
« Reply #7 on: August 29, 2017, 06:11:26 pm »
Check out ebay item 361917777471 under £8 delivered 19.5v ac and 3 amp...

Would work perfectly.. cut the end off wire it into your bus and bosh



Offline Josiebenn

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Re: Losing Directional Lights on N Gauge Locos
« Reply #8 on: August 29, 2017, 06:53:58 pm »
Hi, I've found that i do have a 12v transformer that was feeding an HP scanner.  That do it? 

Online ntpntpntp

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Re: Losing Directional Lights on N Gauge Locos
« Reply #9 on: August 29, 2017, 07:01:47 pm »
The CDU is fed from the aux which then runs pos, neg and common earth to a distribution area.

3 wires for the CDU?  Unusual, normally just expect a pos and neg output.  Not saying it's necessarily wrong to have a ground as well, but immediately makes me curious - given the concerns about spikes possibly getting into the track feed?   What brand of CDU is it, out of interest?

I'm not familiar with the Combi, but I would assume/hope the track and the aux are fed from two different taps on the transformer?
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline Josiebenn

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Re: Losing Directional Lights on N Gauge Locos
« Reply #10 on: August 29, 2017, 07:24:54 pm »
No, Sorry, my misleading info. only two wires from the CDU, but each Peco point motor with 4pins fed by peco 3 wire loom, RB,with Grn comm looped to 4th pin, fed by a biased SPDT switch with Red, Book, Grn as Com to the 3 pins, to relay them on a common return. 

Gaugemaster Combi, 1 x Loco speed dial, pair of 12v track connectors, pair of 16v auxiliary connectors.

Online ntpntpntp

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Re: Losing Directional Lights on N Gauge Locos
« Reply #11 on: August 29, 2017, 07:31:43 pm »
OK, that all sounds pretty standard.    The mystery deepens, then!
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline Josiebenn

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Re: Losing Directional Lights on N Gauge Locos
« Reply #12 on: August 29, 2017, 07:37:02 pm »
See above posts.   will next split CDU supply from Combi via independent transformer.  Waiting for confirmation from OnlyMe, that an old 12 v transformer I have will suffice, or must it be 18v?   
Many thanks. 

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Re: Losing Directional Lights on N Gauge Locos
« Reply #13 on: August 29, 2017, 07:39:50 pm »
Hmmm... reading up on the Combi, it seems to be fed from a separate transformer and a single 16vAC input - so the track and aux are NOT on totally separate transformer secondary windings.   So yes, any load on the aux also affects the track power.

We've not proven any theory that the damage to loco lights is coming from spikes, but all the same I think you'd definitely benefit from powering any accessories from a separate supply as has been suggested.

12V should work for a CDU, but 18V is better!

My own approach is slightly different, I have individual CDU modules for each point (When I started on the layout 20+ years ago I was anticipating automated / computer control for my layout, though that's never actually come to pass). I run these little CDUs on 24V!
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline Josiebenn

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Re: Losing Directional Lights on N Gauge Locos
« Reply #14 on: August 29, 2017, 08:15:01 pm »
Thank you Nptx3.   Presumably 12v can't do damage as it's less than 18v.  I find I've got a choice of the first 12v transformer I mentioned at 1250mA, or an other at 12v at 1500mA. Be nice if this second option works, as then I don't lose the (old and rarely used but functional) scanner. 

Just checking, being AC but going to a CDU that drives points, presumably there is no Pos/Neg wrong wiring danger, just goes one way or t'other through the points motor?
TVM.

 

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