Zimo MX816 decoder Bachmann 2MT

[JZ]

Just been running my Ivatt 2MT. It has a factory fitted Zimo MX816. After about 5 minutes running this afternoon, it slowed to a halt. No amount of tapping it, shutting off power and re-applying, would get it to move. Finally I pressed the stop button on the controller on and off and it restarted normally. After a couple more minutes it slowed again. After that it would run for between 15 seconds and a couple of minutes maximum. So the question is, is it a decoder fault, or does it have some kind of 'fuel load'. FYI, this is the first Zimo decoder I have had and I am using a MultiMaus.

[Nigelcliffe]

Sounds like chip over-heating and shutting itself down.   It shouldn't happen, but could for several reasons.

 

a - something slightly binding in the mechanism creating drag, increasing motor load.

b - poor motor quality

c - too many volts from the DCC system

d - maker (Bachmann) a bit optimistic in specifying an 0.7A rated decoder for OO use. 

 

or a combination of the lot.

 

 

Now, the MultiMaus may be part of the issue for (c ).   For a long time, Roco shipped things with a transformer, rather than a switched-mode power supply.  And that transformer was designed for German voltages of around 220-230v, rather than the UK voltage of 240v.  That makes the output too high. Combine that with transformer output not being linear (so can be higher on light loadings) and the track voltage can get silly-high.    Can usually be fixed by replacing transformer with a switched-mode power supply. 

 

 

You'd be within your rights to ask the retailer for a replacement/refund on the loco.   As described, it is not behaving correctly. 

 

 

- Nigel

[JZ]

Thanks for the insight Nigel. Further testing shows that it stops, or at least slows to a halt, at whatever the deceleration setting is and occurs either while climbing or immediately after the steepest part of the layout. What's more, it does not occur when the loco is running light. I've been running MultiMaus for about 12 years now and this is the first time I have experienced this behaviour. Tempted to switch the decoder for a Lenz, or maybe rip out the Next 18 fitting and put an 8 pin in instead.

[TWG]

I suggest that you would do well to determine the cause of the problem first.  The fact that the loco gives up when hauling a train up a hill suggests that the decoder is overloaded.  The current capacity of the Lenz Next18 decoder is only marginally higher than the Zimo, so a substitution is unlikely to make any difference.  Putting in an 8pin socket will allow you to use a more powerful decoder, but a modern motor should not consume more than 700mA even going uphill.  Have you any means of measuring the current drawn by the loco?

 

Have you ruled out Nigel Cliffe's suggestion (a) above?  It might be worth asking Bachmann if they have come across other instances of this problem. 

 

You do not say how long you have had the loco.  If it is new, then Nigel's suggestion of a return to the retailer is a good one.  Zimo decoders are of excellent quality, but it is possible that the one in your loco is faulty.  Do you have another loco with a Next18 or know someone who has, so the decoder could be tested?

[JZ]

 

 

You do not say how long you have had the loco.  If it is new, then Nigel's suggestion of a return to the retailer is a good one. I bought it when it was released with the new chassis. About 6 months ago?

  Zimo decoders are of excellent quality, but it is possible that the one in your loco is faulty.  Do you have another loco with a Next18 No.

Or know someone who has, so the decoder could be tested? No.

 

 When I have a few minutes, I will give it a full reset and try again. May also put a little lube on the gears and motion to see if that helps. One thing at a time though.

[Nigelcliffe]

 

You do not say how long you have had the loco.  If it is new, then Nigel's suggestion of a return to the retailer is a good one. I bought it when it was released with the new chassis. About 6 months ago?

  Zimo decoders are of excellent quality, but it is possible that the one in your loco is faulty.  Do you have another loco with a Next18 No.

Or know someone who has, so the decoder could be tested? No.

 

 When I have a few minutes, I will give it a full reset and try again. May also put a little lube on the gears and motion to see if that helps. One thing at a time though.

 

 

Lubrication probably won't help, and may make things worse (and may result in a row with supplier about end-user abuse if you end up returning it). Most RTR locos are supplied with too much grease and other gunk applied at the factory, not too little.  If its a tight spot in the mechanism, it needs dismantling and working out why, which can be a protracted job, and not recommended in this case - the loco is new, its still available as a current item, so get the supplier to sort it out. 

 

You say it slows to a stop following the deceleration settings ?   That's not totally typical of a decoder cutting out due to over-heating.   I'm wondering if the wiring of the layout isn't quite up to standard and the signal from the DCC system is garbled in some way when reaching the "slope" you mention.   Is it possible for you to run an additional pair of wires directly from the command station to the track in the vicinity of the slope ?    Could you read the CV's in the decoder to see if it has "brake on DC" turned on ?

 

 

 

If you are of the view that its not too many volts from the MultiMaus system, and can't pin the cause down to layout wiring, then I strongly recommend you return it to the retailer who supplied it for replacement/refund, rather than either lubricating it or dismantling the loco.   If it's "about six months", then get your skates on because absolute consumer rights are very much stronger in the first six months, though still fairly strong for several years.   Consumer law in the UK is that you return things to retailers, not manufacturers, so don't be fobbed off by a retailer who is avoiding their responsibilities. 

 

 

- Nigel

[JZ]

I won't have a problem returning it, if necessary. I have an early finish tomorrow and will get it on the Sprog to check it out. One thing I didn't mention is that it ran fine when it was new. It was then put away for a few months, though I can't see that impact that would have.

 

 

 

Edit: In the 30 odd minutes since posting this and not having to get up tomorrow until 04:45 (working on the railway give you a whole different perspective to 'having a lie in') I have been out and done the full reset and then given it a continuous run of about 15 minutes, loaded with 5 Hornby Hawksworth coaches. No issues at all. Normally it would probably be two or three carriages. It's previous load, when the issues arose, was 4 Bachmann well wagons, loaded with Bachmann boiler loads, 1 Kit-built, brass, lowmac with a twin cable drum load and the new Hatton's warwell, again with a resin transformer load. Quite a hefty load for a small motor and maybe the cause of overheating, if indeed that's what it was.

Edited June 28, 2017 by JZ