Atlas GP7 - Repairs

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Gloriousnse
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Re: Atlas GP7 - Repairs

Post by Gloriousnse » Tue Apr 30, 2013 11:10 am

Welcome to the organisation and the forum!

Can you tell us a little more about what the issue with it is? Most US diesels aren't too hard to fix yourself if you can work out what's causing the problem, and Atlas are not bad at supplying spares.

(Posted from my mobile)
Martyn Read

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Gloriousnse
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Re: Atlas GP7 - Repairs

Post by Gloriousnse » Wed May 01, 2013 9:20 am

You can order Atlas parts direct from their website - https://secure.atlasrr.com/mod1/items.a ... LPARTS&Bc= - you can search on a part number from the exploded diagram in the box, you might need to put a 9 in front. Ordering parts direct from them is cheap and quick, and they don't rip you off on postage either.

But i'd try a couple of things first.

That's based on experience - i've never had one of these motors die through old age, and some in my fleet now date back to the 80s! If the issue isn't caused by the motor then buying a new motor is just a waste of money - it still doesn't give you a working loco!

So...couple more things which are worth trying first before buying parts.

1. When you say the motor stops intermittently, when the motor stops, listen carefully. Does it continue to hum but not turn, or does it just stop and go quiet?

If it goes quiet when it stops then i'd suggest you have an electrical connection issue and not a problem with the motor - check all the connections between track and motor - are you wheels clean (I know that sounds silly, but i've bought old 'broken - sold for spares' loco's before that when I got them home just needed a heavy wheel clean!!) - are the pickups connecting with the wheels, are the wires properly connected to the trucks and the circuit board, and wires again properly connected between circuit board and motor?

If the motor hums but doesn't turn then it might be the motor - but it could also be a drivetrain issue, such as a broken gear preventing the motor from turning. Pop the top off the worm gear covers and remove the worms then run it again, does the motor now run freely?

If the motor runs freely when it's *not* connected to the drivetrain then the motor is not the problem, the problem will likely be a broken gear in one of the gear towers. If it's this problem you can probably tie down which gear tower has the fault by connecting up just one end to the motor and testing again, then the other...

An 'unhealthy noise' could be related, or could just mean it needs a bit of minor attention, depending on the noise - a loco making a screechy noise for example isn't neccesarily terminally afflicted, it just needs a little lubrication somewhere.
Martyn Read

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BrianMoore
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Re: Atlas GP7 - Repairs

Post by BrianMoore » Wed May 01, 2013 11:21 am

Another episode of "Doctor Read's Casebook", I see.

Is ma dinner ready, Janet?

As the good doctor says, most of the problems you encounter with locomotive electrics are relatively easily solved by a process of elimination, and are usually easily fixed too.

Good to have you aboard.
Brian Moore

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Gloriousnse
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Re: Atlas GP7 - Repairs

Post by Gloriousnse » Wed May 01, 2013 11:39 am

That down-home Scottish reference would be before my time Mr Moore... ;)
Martyn Read

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BrianMoore
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Re: Atlas GP7 - Repairs

Post by BrianMoore » Wed May 01, 2013 11:45 am

Gloriousnse wrote:That down-home Scottish reference would be before my time Mr Moore... ;)
I wonder if the Tannochbrae American Railroad Emporium is still open?
Brian Moore

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torikoos
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Re: Atlas GP7 - Repairs

Post by torikoos » Wed May 01, 2013 5:57 pm

pennsyman wrote:Thank you so much for the time and trouble you've taken in sending me such a detailed reply.. it's truly appreciated.

I'm already wondering why I've waited so long before joining the NMRA(BR)!!

Pennsyman
Have a look at the members directory and see if there's any others living near you. There's a good chance they can help you , or know someone who can. If all fails, I'm sure if you ask, there will be members here that are willing to look at it for you as a 'favour' , if you can get the loco to them (or send it and pay the shipping , and some parts if needed ) but it really isn't that hard. Good lighting, a bit of patience, a cup of tea and some basic tools are what you need, don't rush it, take your time.

Welcome aboard. Koos
Koos Fockens -Devon UK. North American Model Railroading
Age is just a case of mind over matter. If you don't mind, then it doesn't matter.

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Re: Atlas GP7 - Repairs

Post by Mike_R » Wed May 01, 2013 7:53 pm

Following on from Martyn's suggestions, if you have a d.c. ammeter, such as on a multimeter (an old analogue one is best) connect it in series with the power supply (d.c.). If the current drops off when the motor stops you have a bad connection, if it goes up something is binding.
If it takes more current set the motor turning over slowly, does the stopping happen at the same place in the motor's revolution (put a mark on a flywheel to make this easier to see), if so it is probably the motor, if it happens at different places with several turns between then it is the drive train.
One last thing, is it the same in both directions? If only one then it is probably the motor, drive shafts, flywheels or worm gear. They tend to move from one end to the other when reversing. I had a loco (brand new) where one flywheel rubbed against the chassis, but only one way.

As Martyn said sometimes a second hand loco just needs stripping down, cleaning and relubing.
Mike Ruby

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Re: Atlas GP7 - Repairs

Post by mikehughes » Thu May 02, 2013 9:17 am

pennsyman wrote:Thank you so much for the time and trouble you've taken in sending me such a detailed reply.. it's truly appreciated.

I'm already wondering why I've waited so long before joining the NMRA(BR)!!

Pennsyman
Welcome to the NMRA. You're experiencing just what is best about the organisation - sharing know-how.

If you let us know where you live we may be able to suggest where you can meet up with someone that can help.

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Gloriousnse
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Re: Atlas GP7 - Repairs

Post by Gloriousnse » Thu May 02, 2013 10:01 am

mikehughes wrote: sharing know-how.
I was waiting for somebody to say that.... :lol:
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BrianMoore
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Re: Atlas GP7 - Repairs

Post by BrianMoore » Wed May 08, 2013 10:33 am

Good to know you got it running again, and that you also appear to be through the "intimidation barrier" (been there, got the t-shirt), which is the most important result when working on such things.
Brian Moore

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