Problem with Bemo Allegra

[MichaelE]

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Post by michael on 1 minute ago

Please watch this video I made this afternoon and let me hear your thoughts. I do not know what is wrong, but the Allegra is now doing what the ABe 4/4 III has been doing for months now. 

Measured RMS track voltage is what you see in the video when standard gauge Roco and Peko locomotives are running. I can run up to five DCC sound locomotives at a time using the NCE Powercab, but I get what you see in the video trying to run one DCC sound Bemo locomotive.

There are power drops every 4-6 feet on the meter gauge track and voltage checks good.

I don't understand what is wrong with these Bemo locomotives.

Any ideas or suggestions would be welcome. I'm on the verge of sending both of these units back to Bemo in Germany for service, but I hesitate because I probably won't see them for the better part of a year or more.

 

 

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Edited June 13, 2022 by MichaelE

[MichaelE]

I believe this is a heat issue that is slowly damaging this decoder. The decoder is in such a small confined space there is virtually no way to cool it and there is no airflow for heat to escape.

 

It ran fine for about 30 minutes earlier, and as soon as it started to heat up, the lights started flashing and it stopped. As soon as it came to a complete halt, the lights remained on steady but it wouldn't run again.

[Jim Easterbrook]

Have you compared the current being drawn by "good" and "bad" locos?

[MichaelE]

Yes. No change with a normally operating locomotive. The only time there is a slight increase is on a grade, and then a subsequent decrease when descending the grade.

 

I'm going to swap the decoders and see if the decoder is the problem or the locomotive. I'm also going to remove the decoder cover on the roof of the power unit and see if that makes a difference with some airflow.

 

I've taken the power unit from the Allegra down to component parts and found no binding, it is properly lubed, and drivetrain rotates freely.

[Jim Easterbrook]

Yes, it does sound as if the heat from normal operation could be the problem. But I'd have expected an increase in current (which would cause an increase in heat) when the track voltage drops.

[MichaelE]

Current does increase, to over an amp, while voltage drops.

[MichaelE]

I sent the decoder back to ESU in the States for replacement.

[JimFin]

On 19/06/2022 at 12:52, MichaelE said:

I sent the decoder back to ESU in the States for replacement.

Hope that solves it. Did an install for a pal at the weekend. Looks like it would be possible to create some venting by cutting away some of the black "box" section in the AC unit which would allow heat to escape via the AC grills. Having said that - not had a problem with mine, even with exhibition use.

 

 

[MichaelE]

I was looking at that cover thinking of modifying it to allow heat to escape. 

 

I'm hoping I just got  bum decoder.

 

I don't think that was good planning on Bemo's part to place the decoder in such a confined area with absolutely no way for heat to escape.

[MOB FAN]

Have you entertained the thought of switching to another brand of decoder?

[MichaelE]

No. I have a Lokprogrammer and would not like to see that being wasted.

[MichaelE]

ESU determined the decoder to be bad. The dealer refused to replace it, however, ESU told me that the dealer should have replaced it and then received credit from ESU for the bad decoder.

 

Unfortunately, ESU could not help me with this dilemma since they were already in possession of the decoder I sent to them. They are out of stock of the decoder and has been backordered with no expected date. Swell.

 

In the mean time, I have removed the backing pieces that block the vents on the decoder cover on the roof of the Allegra and hope this will help with the heat issue. If I ever get a replacement.

[MichaelE]

ESU wrote to me and informed me that they have sent my replacement decoder for the Allegra. I hope this one works better than the first.

 

[MichaelE]

There was no change in operation after decoder replacement. I contacted Bemo for warranty service and they said they would send me a new motor. Based on my explanation, they say that the motor is failing or has failed.

 

 

[MOB FAN]

In your first post you said you had the same problem with an ABe 4/4 III.

What happened with it?

[MichaelE]

That is out of warranty so I suppose I will have to purchase a motor for it.

 

I think that it is quite the coincidence that my first and only two Bemo locomotives experienced the same exact problems. The only difference is that the ABe 4/4 III lasted a full 18 months before the problem started and was very intermittent for awhile before becoming critical and finally failing too.

 

I have not read about any touble with Bemo locomotives of this sort on any of the RhB or Bemo forums. I can't understand why this problem has occurred or how to prevent it in the future. 

 

I see Bemo locomotives on layouts with steeper grades than what I have built pulling three and four times the rolling stock and I never hear about the problems I'm having.

[DGO]

Possible electrical supply fault burning out both motor and decodet ?

[MichaelE]

I don't know how that could be when the standard gauge locomotives have been running fine for more than four years. It's all the same electrical supply.

[DGO]

4 hours ago, MichaelE said:

I don't know how that could be when the standard gauge locomotives have been running fine for more than four years. It's all the same electrical supply.

 

Very odd but I suppose the controller could have failed first and caused the motor to die

[MichaelE]

The new motor arrived last month, but with the cooler temperatures here lately I have not yet installed the new motor. Too nice outside to be inside.

 

I'll get around to it in a week or two. I hope.

[MichaelE]

I was finally able to get the new motor installed and the Allegra is running like new. I guess mine had a bum motor from the factory. I hope this one holds up.