Dead Bachmann Lyn

duncan1_9_8_4

duncan1_9_8_4

UK Railway Signaller and Garden Railway Operator
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Help, again. Having a small running session with just my Lyn on my dads circuit, the Lyn suddenly went really slow, then to full speed and stopped. Nothing at all. I have taken the chip out, which smells of burning and it is black. The loco will still not work on analogue too. Any ideas? The railway is powered by all brand new Massoth equipment, and the chip is/was a Zimo MX632r. It has been fine for 3 years with no problem, but now this. Is it worth getting repaired given I can get brand new Lyn for around 180 quid? Thanks.
 
Personally I think it depends on the version of the loco.
If it's an early one I'd scrap it, if it's the latest version I'd repair.
 
Whatever you decide to do with the loco it's worth bearing in mind that Digitrains will do a decoder exchange for £15 plus the post.
Saves you waiting for a factory repair and post to Vienna:-)
 
You say you took the decoder back out, have you replaced it with the dummy plug? I don't have the later production Lyn, but going by the service sheets it has an NEM652 8 pin socket? If you have replaced the plug correctly then maybe the motor has blown or perhaps part of the main board? Something's obviously caused the decoder to fry.
 
Last edited:
ntpntpntp said:
Something's obviously caused the decoder to fry.
Click to expand...
That's the logic behind my suggestion. The decoder will need to be replaced/repaired/exchanged in any case. Before this it needs to run O.K. without a decoder for test purposes. I suspect spares for the current version are available at a reasonable price but not for the early ones.
 
Been in touch with PSmodels, he thinks it may be to do with a "flux ring " left on the motor. Looks like a repair, and oportunity to add sound, and etc properly. I will keep you informed. Message from PS, = blown probably due to the
Antiferance flux ring being left on the motor.All Bachmann and Aristocraft
locos have this and it has polarised capacitors fitted .These have to be
removed because when you change to DCC it will charge them in forward motion
but in reverse it blow the arse out of them .
 
Eh? Never ever read of anything related to motor flux rings and DCC. A flux ring is a metal sleeve around a motor casing to control magnetic field and improve torque.

It is true that some models have interference suppression capacitors fitted across the motor connections and some people say remove these when converting to DCC as they can upset BEMF. Can't say I've ever had to bother with this myself. There have been instances of certain unchipped locos blowing these capacitors if placed on a DCC track (Piko locos I think?), but again I wouldn't recommend this even though some DCC systems support controlling one unchipped loco by bending the DCC waveform.
 
umm..... the voltage to the motor is reversed in polarity when the loco runs in the opposite direction, no matter whether it is DC, DCC, MTH, or aliens.

Those noise capacitors are non-polarized.

I think the person who gave you this advice got their training in electronics from the movie "Back to the Future" where a mythical flux capacitor provided the energy to jump through time.

in the OLD days, DCC decoders would be upset with the noise capacitors, they confused the BEMF circuitry.

Get some more knowledgeable advice. Try testing the motor with DC and see if it is ok...

Greg
 
Some of the Bachmann Spectrum 4-4-0 and 2-6-0 locos had suppression pcb's mounted on the ends of the motors. On those models Bachmann used 47mf / 35 volt electrolytic caps that should have been wired nose to nose or tail to tail but they were not. In one direction they worked OK but in the other one cap would blow up. I have never seen that arrangement used on Bachmann Lyn locos.
I agree with Greg. Nowadays Bachmann use RF chokes and non polarised caps.
 
So the locos fitted with electrolytic caps on the motors would blow up on DC. I think this is the situation where something was true once upon a time and the "knowledge base" was not updated to current situations.

That specific example combined with the old information about ANY caps across the motor causing problems with DCC seems to have been the formula for the response you got.

I've not had any problems with noise suppression caps lately with DCC but it's still possible they will cause a "misread" on the BEMF voltage used for motor control.

But in any case this should not burn up a decoder.

Greg
 
1. Ignore everything else. Disconnect one lead from the motor. Using a bench supply with ammeter, run the motor by connecting directly to it.
How much current does it consume?
Will it run smoothly at low speed in BOTH directions?
Up the speed to 'quite fast' (see Haynes manual for definition of quite fast). Does it sound rough? How much current does it draw now?
Then when you know the motor is OK..
2. Get the loco to run on DC.*

*You can bypass this step IF you are going to put a direct replacement chip in it. AND you can afford the throw away the cost of said replacement.

3. The £15 swapout sounds a bargain! - Even if you have to pay carriage both ways..
 
It is a bargain Phil. Zimo have a £15 flat repair rate for decoders and Digitrains add a level by sending you a new decoder on receipt of your fried decoder and the repair fee.
 
shropshire lad said:
It is a bargain Phil. Zimo have a £15 flat repair rate for decoders and Digitrains add a level by sending you a new decoder on receipt of your fried decoder and the repair fee.
Click to expand...

WOW! That is very good..
So good, I think I will have to talk to them about my getting Zimo from them..
Thanks for the info, and 'heads-up'.
:clap::clap::clap:
 
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