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Author Topic: Class 31 only runs one way  (Read 1457 times)

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Offline Murray B

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Class 31 only runs one way
« on: October 14, 2016, 04:48:49 pm »
Having sorted out pick ups on one bogey (see post Class 31 pickups) the loco will now only run one way!  I have had the defective bogey in and out a few times as it took 3 goes to get  the dry  joint (see previous post) on the bogey 100% effective.  Up until now, each time the bogey has been replaced the loco has run both ways.
I have:
1.  Checked the track with both another loco and multi-meter - its fine with  the loco running in both directions.
2.  Taken out the repaired bogey and the problem persists with just the other bogey on the track.
3.  Continuity checked and also power checked the repaired bogey on the track - its fine.
The lights do not come on in the direction that the loco will not move.
The drive shaft appears to be free turning in both directions - with the repaired bogey out I have turned it manually.
When putting power on in the direction that the loco will not move, the drive shaft makes about a half a turn slowly and stops.
The loco is running analogue - I have checked that the DCC blanking plate is properly located.
Any one any ideas?



Offline austinbob

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Re: Class 31 only runs one way
« Reply #1 on: October 14, 2016, 04:52:19 pm »
Could be the faulty light is shorting out when you try and run in that direction. Is there any way you can disconnect it?
 :beers:
Size matters - especially if you don't have a lot of space - and N gauge is the answer!

Bob Austin

Offline PLD

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Re: Class 31 only runs one way
« Reply #2 on: October 14, 2016, 05:02:32 pm »
Could be related to the lighting circuit as Bob says but I'd suspect the associated circuit board rather than the actual lights... The lights are LEDs which if functioning correctly allow current to flow one direction only...

When it isn't running, is it because the circuit is broken or because there is a short circuit? Does your controller give any indication - does it have an overload indicator, what happens to second loco placed on the same track at the same time??

Offline Only Me

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Re: Class 31 only runs one way
« Reply #3 on: October 14, 2016, 05:15:31 pm »
Soubds like sonething stuck in the gear train



Offline Murray B

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Re: Class 31 only runs one way
« Reply #4 on: October 14, 2016, 05:28:56 pm »
Thanks for the ideas and quick responses  - much appreciated.
I have taken the body off.  Continuity check of red led connections does not indicate a short.  The white led for the headcode comes on in the working direction of travel but not the one in the failing direction.
Putting a second loco on the same track (an older Flying Scotsman) with the 31 - the Scotsman works properly in both directions with the 31 following one way and failing the other whilst the Scotsman is still running properly.
The controller is a Gaugemaster combi and does not show a short.
With one bogey removed I can turn the worm drive in both directions easily.

Offline Only Me

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Re: Class 31 only runs one way
« Reply #5 on: October 14, 2016, 06:01:41 pm »
Can tou turn the bogey gears in each direction though



Offline Izzy

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Re: Class 31 only runs one way
« Reply #6 on: October 14, 2016, 08:01:30 pm »

I am assuming you haven't altered the lights via the switch on the top of the circuit board? But in any case this wouldn't stop the loco running in both directions.....

As you don't seem adverse to working things out yourself perhaps it might be best to remove the circuit board and both bogies, and check that the motor runs freely in both directions. Then add the board back, then the bogies. Might be the only way of finding where the problems lie as re-soldering the bogie pick-ups wouldn't affect the circuit board as far as I can see.

Izzy


Offline Murray B

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Re: Class 31 only runs one way
« Reply #7 on: October 15, 2016, 02:45:33 pm »
Once again, thanks chaps for the suggestions - much appreciated.
The light switches on the top of the board are set to on and I have not moved them.
I have taken out the second bogey and the gear train moves freely in both directions.
I removed the circuit board from the chassis and manually checked that the motor revolves freely in both directions.
I then replaced both bogies and again, with them in place, the motor moves freely in both directions.
I replaced the circuit board and the loco continues to just move- in one direction with the head code LED only working in that direction.
Just in case, I completely removed the DCC blanking plate and put it back in in case of a dodgy contact.  It made no difference.
Noting that there are, what appear to be, two feeds to the motor coming from the circuit board and marked M+ and M-, I put the multi-meter on them to measure the voltage.  In the direction that the loco actually  moves, I am getting about 0.5v below track voltage.  In the direction it doesn't move I am only getting a constant 0.3 volts, however much voltage is applied to the track.  To me this indicates an electronic component failure somewhere on the circuit board but I am no electronics engineer.
I have not applied voltage direct to M+ and M- for fear of blowing a component on the board through feeding it the wrong way!
The loco is new from a retailer.  At this point I am now tempted to return it as faulty - unless anyone can come up with something else worth trying.
Again thanks for everyone's prompt help and suggestions.


Offline Only Me

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Re: Class 31 only runs one way
« Reply #8 on: October 15, 2016, 03:14:13 pm »
Only other thing to test is meter out each wheel set, they should not produce conductivity



Offline Malc

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Re: Class 31 only runs one way
« Reply #9 on: October 15, 2016, 03:15:15 pm »
Sounds like there is something acting like a diode on the circuit board that shouldn't be. I would take it back. You could do a visual check to see if there are any stray whiskers of solder bridging across tracks, particularly if you had a dry joint previously.
I'm not sure if life is passing me by, or trying to run me over.

Offline newportnobby

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Re: Class 31 only runs one way
« Reply #10 on: October 15, 2016, 03:16:44 pm »

The loco is new from a retailer.  At this point I am now tempted to return it as faulty - unless anyone can come up with something else worth trying.
Again thanks for everyone's prompt help and suggestions.

Not wanting to teach grandma to suck eggs, Murray, but should you send it back don't tell 'em you've been inside it :no:

Offline Izzy

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Re: Class 31 only runs one way
« Reply #11 on: October 15, 2016, 07:32:50 pm »

What I can't quite figure is what could have happened to cause a motor that once ran in both directions to stop doing so. As AFAIK the lighting and motor circuits are separate, so the lights not working shouldn't affect the motor. The blanking plate only connects up these individual circuits (which are controlled by a decoder when one is used) to the track power.

Did you power the motor when the circuit board was removed to check it ran okay both ways under direct power? An open circuit winding can cause a motor to only run one way. Probably best to return it. A can of worms comes to mind.

Izzy

Offline austinbob

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Re: Class 31 only runs one way
« Reply #12 on: October 15, 2016, 07:45:49 pm »
I agree with Newport Nobby. Stuff all the bits back in the loco and send it back under warranty.

Having said that I'm still almost sure that the faulty light (LED) acts as a diode in one direction and a short circuit in the other direction - fairly typical of LED failure.

If you don't want to send it back then try disconnecting the suspect LED.
 :beers:
Size matters - especially if you don't have a lot of space - and N gauge is the answer!

Bob Austin

Online CliveH

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Re: Class 31 only runs one way
« Reply #13 on: October 16, 2016, 08:43:57 am »
Quick diagnostic thought. The feed from the rails enters the DCC socket at positions 3&4 (the centre two) and goes to the motor via 1&2 and the lighting via 5&6. By moving the DCC blanking plug TWO pins across so that pins 1&2 are outside of the socket then the lighting section will be disconnected (positions 5&6 are empty). If the loco runs OK (forward & reverse will be transposed) then the issue will be in the lighting circuit.


Cheers

Clive 

Offline Murray B

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Re: Class 31 only runs one way
« Reply #14 on: October 16, 2016, 05:54:24 pm »
I have removed the circuit board and run power directly to the motor - it runs both ways which suggests to me that there is a fault on the circuit board.
With the body off and so disconnecting the red LEDs, the white one on the circuit board that does not work is the one in the failed direction of travel.  I cannot see how to disconnect it so I have not pursued that.
I have also shifted the DCC blanking plug as suggested by Clive - that made no difference.
I have therefore decided that that is enough and it is going back under warranty!
Thank you all for your advice and speedy responses.  I am just starting out actually doing something in N Gauge now that I have retired though I have been a "sleeping member" for donkeys years.  This is the first time I have used the forum and I am impressed by all your advice and help and the speed of your responses.  Thank you again.
Murray

 

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