Hi all,
I've got a small problem that you might be able to help me with.
Now I need to try and describe it..
My father has a small OO gauge layout that has three dapol motorized home signals, he uses a Relco track cleaner in his set up.
Everything worked fine for him when he first wired it up then one day one of the signals went crazy and kept going up and down. After thinking about it he switched off the Relco unit and everything went back to normal. Yesterday I popped over for a visit and offered to have a look. Now everything has gone strange. With a loco on the track and the Relco switched on all is well, signals work, loco works, Relco works. Then I take the loco off the track leaving nothing, the signals start going up and down. They seem to work every 10-20 seconds. I then pop the loco back on the track and everything settles down.
I don't visit that often so it might be a while before I can fiddle with it again.
Any ideas??

Yes - don't use a Relco!  Seriously.  They don't really keep the track clean - htey rely on 'burning off' the dirt, which will leave a 'sooty' residue behind.  Better, by far, to use mechanical methods (polishing) and/or solvents.  And, as you've seen, Relcos cause electrical 'issues'.

Sounds like some kind of problem of electrical interference.  Probably when there is no loco there the Relco senses there is no circuit and assumes this is due to dirty track, so gives it a blast of high voltage from time to time in an attempt to clear it. 

If you want to keep the Relco then you could try making sure that the Relco and the signal are fed from separate power supplies and also that the wires to the signal are kept as far as possible from the wires feeding the Relco and the wires from the Relco to the track. 

A word of caution under no  circumstances use a Relco unit on a  DCC  Layout

I was asked reecntly if they could be used &  the answer is no unless you dont like your  DCC  control   & locos  &   would like to see them  smoke / blow terminally  ................. back to the  original  post. 

Can totally confirm what upnick says about Relco & DCC.  I took a couple of my DCC sound fitted locos to run at an exhibition last year our club DC layout after switching the necessary CV to allow DC running and didn't realise it had HF cleaning fitted.  Result, an expensive mistake, 3 sound decoders burnt out (class 108 had twin sound decoders fitted).      

Quote from: upnick on April 14, 2013, 10:14:46 AM
A word of caution under no  circumstances use a Relco unit on a  DCC  Layout

Depends on if you like your 'chips' fried or oven baked! 
Seriously though everyone, heed upnicks advice!

Back to the post, I would say its the loco making the circuit like edwin_m says.
Would make sense, so yes, feed it separately and that will probably solve the problem.

Quote from: davidjhope on April 14, 2013, 08:55:20 AM
...With a loco on the track and the Relco switched on all is well, signals work, loco works, Relco works. Then I take the loco off the track leaving nothing, the signals start going up and down. They seem to work every 10-20 seconds. I then pop the loco back on the track and everything settles down....

If I remember correctly, Dapol advices 16V AC for the signals and guessing your fathers layout is 12V DC I would expect two separate power supplies and no electrical connection between signals and any track electrickery. In this case I'd have a look at the routing of the track and signal wires. Are they close to each other?
But first I'd make sure what power supply is used for track and signals and that there is no electrical connection, like a shared ground wire.

Quote from: MacRat on April 14, 2013, 11:41:20 AM

Quote from: davidjhope on April 14, 2013, 08:55:20 AM
...With a loco on the track and the Relco switched on all is well, signals work, loco works, Relco works. Then I take the loco off the track leaving nothing, the signals start going up and down. They seem to work every 10-20 seconds. I then pop the loco back on the track and everything settles down....

If I remember correctly, Dapol advices 16V AC for the signals and guessing your fathers layout is 12V DC I would expect two separate power supplies and no electrical connection between signals and any track electrickery. In this case I'd have a look at the routing of the track and signal wires. Are they close to each other?
But first I'd make sure what power supply is used for track and signals and that there is no electrical connection, like a shared ground wire.

Relco's use 16V AC, hence the advice not to use them with DCC!

Quote from: moogle on April 14, 2013, 11:44:42 AM
Relco's use 16V AC, hence the advice not to use them with DCC!

Thanks, I never used them, so I didn't know. Well, in this case I can see why one would connect track and signals to the same supply. I'd expect a separate AC supply for the signals should cure this than?

I would think so yes.
After all, you run point motors on their own circuit so why not signals!

The Relco injects a high voltage spike into the track supply when it decides the rails need cleaning.  So there is definitely a risk of inductive coupling between the Dapol signal wires (power or control) and the track feeds particularly if the two run parallel and/or the feed and return of either is widely separated (as typically happens on common return layouts). 

Unless the Relco has some big capacitors internally it may also put spikes onto its own 15Vac inputs, which could affect anything else on the same supply by conductive coupling, or wiring nearby by inductive coupling. 

It's not just DCC you want to avoid using a Relco with its any integrated circuit of any kind. That includes LEDs (although they are less vulnerable) and some of the circuit boards in modern locos. The high voltage pulse is also unlikely to be within the specification of modern loco motors either.

High voltage spikes gradually damage integrated circuits of all kinds. It's why for example when changing PC memory you are supposed to be earthed.

My guess would be that the Relco and the Dapol signals are controlled off the same 16v AC accessory supply ? I imagine the Relco is putting spikes on that too when it pulses and the power draw suddenely rises. If so then using a different supply for the signals should help.

Alan

Hi all,
Thanks for all your replies, sorry my reply is late.

My father has a 16v AC transformer (Possibly Gaugemaster) which has two 16v AC outputs. One is feeding a Gaugemaster hand held unit the other is feeding the Relco's. He has unplugged the hand held and feed the signals from the 16v feed. To control the layout he has a fixed 12v dv panel mounted controller which is feed by a separate 12v dc power supply. Why he has two controllers for such a small layout is beyond me.
What I will do is try and get a separate 16v AC power supply to feed just the signals.
Any suggestions before I go searching?
I will then check that all the wiring is kept separate from the track wiring.

Thanks again

David

Personally I would junk the Relco's and use that outlet for the signals.
For a small layout I think a rag dampened with IPA would give better results than the Relco's anyway

Quote from: newportnobby on April 17, 2013, 02:25:25 PM
Personally I would junk the Relco's and use that outlet for the signals.
For a small layout I think a rag dampened with IPA would give better results than the Relco's anyway

I totally agree with you.
How would you like to talk to my old stuborn father and explain things to him, I gave up trying years ago.
I have found just going along with him is a happier place to be.
He could clean his track with IPA in less than five minutes.
I will try and convince him next time I see him.
I believe scrapping the Relco's is the best option.

David