# AF 12B transformer problem



## McMike (Nov 20, 2017)

I have an American Flyer 12B transformer and set that I took out of the box after quite a while (decades). The transformer is providing only intermittent power to the posts. In particular, it seems to work okay after a rest, then works intermittently, and then stops working, all within a couple-few minutes. I don't think it is because of shorts on the rail, since this happens without load when tested at the posts.

I noticed it was vibrating (buzzing) fairly loudly when initially used, sometimes the buzzing was quieter or even stopped entirely. It does not seem to be obviously tripping the breaker, and does not respond to resetting the breaker..

I opened the unit up and everything actually looks okay, not very much corrosion, solders look okay. I saw no obvious loose wires, but I didn't try every single connection point. I used some deoxit to clean up the contact assembly and contact arm. I verified that the contact arm was making decent contact with the coil. I cleaned up the moving parts with some deoxit.

So I am out of ideas on what to clean or wiggle. Thanks.


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## mopac (Feb 24, 2011)

I have a 12B also. But it is not doing those things. No idea on the buzzing. Mine is fairly quiet. I have not been inside mine. I have gone through my lionel ZW transformer.
One thing I did was to take a green scotch bright pad to the coil. Where the roller rolls. And then wiped it with alcohol.
How is your rollers? The intermittent voltage could be at the coil. If there is a black strip
on your coil where the roller rolls I would clean that.

Welcome to the forum.


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## McMike (Nov 20, 2017)

mopac said:


> How is your rollers? The intermittent voltage could be at the coil. If there is a black strip
> on your coil where the roller rolls I would clean that.
> 
> Welcome to the forum.


Thank you.
Mine does not have rollers, only a copper contact tab, which I cleaned.
I noticed the black strip. I tried to clean it a bit, but not with an abrasive. I could try that.


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## mopac (Feb 24, 2011)

I thought mine had rollers but I guess not. Like I said I have not been inside. If it
is a pretty heavy duty coil it should not hurt to use the green pad. On my lionel it made the coil look brand new. No more black strip.

That black strip area is a place of contact for voltage. I am not saying that is your problem area but would not hurt to clean it.

You should get some other people commenting during the day. We have some knowledgeable people
on this forum. LOL. Me not being one of them.


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## cramden (Oct 13, 2015)

This is from the repair manual: When a transformer hums, it generally indicates that the wood wedges have become loose allowing the coil to vibrate. This can be overcome by adding an additional wood wedge. I've never come across this so you'll have to look for the wedges and see what you can do. Here is some more tests found on Portlines.comhttp://www.portlines.com/portlinesclinic6.htm Wish I could be more helpful. Thinking of this you might not want to mess around with this and just get a transformer that's known to be good.


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## mopac (Feb 24, 2011)

I googled buzz in American flyer transformer.I was hoping cramden would chime in. He is right the buzz is a vibration in the transformer. There is a lot on google. I use google often. This may be same site cramden offered up. But here is a link to Portlines on testing transformer. It does say if it fails any of the tests use it for boat anchor. It did not mention fixes.

http://www.portlines.com/portlinesclinic6.htm


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## cramden (Oct 13, 2015)

Mopac gives you the link I referred to at Portlines.com. I've only replaced the power cord or soldered a broken wire with transformers. The metal case transformers can be dangerous if there is any leakage of voltage so be careful with any repair you might attempt.


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## mopac (Feb 24, 2011)

I also saw that no transformer is completely safe. I never leave the room with any of my transformers running.
This comes from when I was 6 or 7 and left my AF transformer plugged in and it burnt out some way. No damage but could have. Transformer was toast.


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## McMike (Nov 20, 2017)

Thanks everyone. I will try a better clean of the coils and double check the contact. And check wedges.

Thanks for the safety warning. I have tested that bugger eight ways to Sunday, have it on a circuit breakers strip, and keep the kids at least six feet away behind a blast wall ;-)

They got a big thrill on the first lap when the old loco trailed a parade of sparks around the living room.


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