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Offline hxmiesa  
#1 Posted : 30 September 2019 13:57:02(UTC)
hxmiesa

Spain   
Joined: 15/12/2005(UTC)
Posts: 2,726
Location: Spain
Hi all,

This is happening with a Märklin DELTA BR41, which has been in my possesion for around 15 years.
It came brand new in a starter-set (one with an oval + 2 switches of K-track and the classic old metal-crane)

Lok has been running perfectly on my analogue layout for the last 12 years.
The older DELTA decoder is the model with 4 micro dip-switches. All in "0" position. (Analogue operation)

SUDDENLY this loko will now -randomly- reverse when going from one power-section to the other.
All my trafos are in synchronous phase!
They are old (light)blue trafos but the dial is never touched; always on a fixed speed-setting.
I *never* use these trafos to give a reversing impulse.
(Including last night I saw it starting in reverse from stop. -Starting in a shaddow-station :-((( )

I am not too sure if this has happened with any any other of my DELTA loks. I have a few (only around a handfull), -but Have only really noticed it with this BR41. Neither old analogues, full digitals or ROCO or Piko digitals has shown this behaviour.

---

The above mentions all the things that I discard out of hand. Other possible problem-sources could be;
Several loks running on the same trafo, inducing "noise" that the DELTA can mis-interpret.
Multiple use of DIODES for various signalling purposes; Signalling is controlled with a 24Vdc system and industrial PLCs. The brown AC "0" is shorted to the 24Vdc "0" in order to exchange signals.
This has worked without ANY problems for 12 years, even with track-detection spots with half-wave power (DC) touching the wheels of the loks.
Can any of that throw off the running-direction of a delta decoder?
What could destroy a delta deco?

Thanks for any comment/suggestion/idea.
Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
Offline mike c  
#2 Posted : 30 September 2019 17:19:29(UTC)
mike c

Canada   
Joined: 28/11/2007(UTC)
Posts: 6,378
Location: Montreal, QC
My deduction is that the locomotive is interpreting the momentary loss of power and the contact with the new power supply as an inversion signal and this is causing it to reverse direction.
What happens if you reduce the output of the transformer by a percent or two? If I am right, the reverse mechanism should no longer be triggered.

Does it only occur with one specific transition or each time it crosses from one power source to another?
Have you checked the layout to ensure that each of your transformers is putting out the correct voltage?

Regards

Mike C
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Offline Henrik Schütz  
#3 Posted : 02 October 2019 22:28:39(UTC)
Henrik Schütz

Sweden   
Joined: 04/08/2015(UTC)
Posts: 38
Location: Stockholms Lan, Stockholm
First generation of delta dont have a memory for direction. Maybe a short interruption in the power supply restarts the decoder and makes it run in the forward direction.

Henrik Schütz , Stockholm

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Offline xxup  
#4 Posted : 02 October 2019 23:12:45(UTC)
xxup

Australia   
Joined: 15/03/2003(UTC)
Posts: 8,946
Location: Australia
Do you have a cat? Cats are sneaky creatures with a wicked sense of humour.. I would not put it past a cat to get up in the night and fiddle with perfectly set transformers.. Laugh
Adrian
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Offline Purellum  
#5 Posted : 02 October 2019 23:26:59(UTC)
Purellum

Denmark   
Joined: 08/11/2005(UTC)
Posts: 3,168
Location: Mullerup, 4200 Slagelse
Cool

What "worries" me most is that it's been working for 12 years........... Cool

I would probably make a small test circle just for this loco, and try to replicate the error. Blink

Or just blame the cat.............. LOL

Per.

Cool
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Offline hxmiesa  
#6 Posted : 03 October 2019 09:07:46(UTC)
hxmiesa

Spain   
Joined: 15/12/2005(UTC)
Posts: 2,726
Location: Spain
Originally Posted by: Henrik Schütz Go to Quoted Post
First generation of delta dont have a memory for direction. Maybe a short interruption in the power supply restarts the decoder and makes it run in the forward direction.
Henrik Schütz , Stockholm

It´s a BR41. It has only ever been running in the forward direction. Even after several months without running, it has always behaved correctly.

Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
Offline hxmiesa  
#7 Posted : 03 October 2019 09:13:14(UTC)
hxmiesa

Spain   
Joined: 15/12/2005(UTC)
Posts: 2,726
Location: Spain
Originally Posted by: Purellum Go to Quoted Post
Cool
What "worries" me most is that it's been working for 12 years........... Cool
I would probably make a small test circle just for this loco, and try to replicate the error. Blink
Or just blame the cat.............. LOL

No cats. Only a couple of dogs, which are NOT allowed in the train room.

Anyways, the situation has improved, although I am still very alert when this loco gets to run.
What I did was removing the shell, and oil the motor and gears. I covered up the conductor for the smoking unit (I dont have one, but just in case it was rubbing against the metal body). I covered up some soldering points on the stator, for the same reason.
Then I pryed open the tender, "touched" all the soldering points and moved the 4 adress dip-swhitches. Pulling at each soldered cable, and making sure nothing was pinched between body parts.

After that it has been running with no problem on the layout, for the last 2 days. I keep it under observation.
Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
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Offline JohnjeanB  
#8 Posted : 03 October 2019 12:46:23(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 555
Location: Paris, France
Hi Per

When aging some components in digital / delta electronics get out of tolerances. Typically capacitor have their value reduced thus causing Alzeimer desease (changing directions).
You may try to replace the storage capacitor on the delta module BUT you need to have a good soldering iron (temperature control and fine tip) and good soldering skills.
The other solution is to replace the delta module with a mld3 decoder (will also work with AC).

Cheers

Jean
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Offline hxmiesa  
#9 Posted : 04 October 2019 11:18:33(UTC)
hxmiesa

Spain   
Joined: 15/12/2005(UTC)
Posts: 2,726
Location: Spain
Originally Posted by: hxmiesa Go to Quoted Post

After that it has been running with no problem on the layout, for the last 2 days. I keep it under observation.

Well, scratch that, because last night it started from stop in reverse direction. (from a shaddow-station)
A gave it a couple of rounds on the layout, and there werent any more fails.

Although I am not afraid of soldering on the deco-board, I am not convinced that it is the "Alzheimer" syndrome, as some of the fails happens when the loco is running, crossing from one power section to another.
Actually, I think it only happens when it is using the shaddow-station trafo.
Can a trafo cause disruption of DELTA locs? (or should I continue to focus on the BR41 specifically?)
Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
Offline RayF  
#10 Posted : 04 October 2019 14:02:49(UTC)
RayF

Gibraltar   
Joined: 14/03/2005(UTC)
Posts: 15,440
Location: Gibraltar, Europe
Originally Posted by: hxmiesa Go to Quoted Post
Originally Posted by: hxmiesa Go to Quoted Post

After that it has been running with no problem on the layout, for the last 2 days. I keep it under observation.

Well, scratch that, because last night it started from stop in reverse direction. (from a shaddow-station)
A gave it a couple of rounds on the layout, and there werent any more fails.

Although I am not afraid of soldering on the deco-board, I am not convinced that it is the "Alzheimer" syndrome, as some of the fails happens when the loco is running, crossing from one power section to another.
Actually, I think it only happens when it is using the shaddow-station trafo.
Can a trafo cause disruption of DELTA locs? (or should I continue to focus on the BR41 specifically?)


As has been mentioned before, Delta and 6080 equipped locos do not have a memory for the direction of travel. After they have been without power they will usually start running in one particular direction, independently of the previous direction of travel. It sounds to me like the change in power from one section to the next is triggering the decoder to reset the direction to the default start direction.
Ray
Mostly Marklin.Selection of different eras and European railways
Small C track layout, control by MS2, 100+ trains but run 4-5 at a time.
Offline H0  
#11 Posted : 04 October 2019 15:47:44(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 13,505
Location: DE-NW
Delta and 6080 decoders do have a memory for the direction of travel. This memory is kept alive by a capacitor on board of the decoder and it should last for minutes.
Without such a memory, analogue operation would be impossible.
1k5 ohm resistors can be used with digital operation to keep the memory alive for longer times when needed.

If the capacitor runs empty, the loco will forget the last direction of travel and will start in the default direction the next time. In the case of a BR 41 this will be smokestack ahead.

Delta forgetfulness should not be an issue with the setup described here as it should occur only if the loco was off power for many seconds.
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
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Offline RayF  
#12 Posted : 04 October 2019 16:01:32(UTC)
RayF

Gibraltar   
Joined: 14/03/2005(UTC)
Posts: 15,440
Location: Gibraltar, Europe
Originally Posted by: H0 Go to Quoted Post
Delta and 6080 decoders do have a memory for the direction of travel. This memory is kept alive by a capacitor on board of the decoder and it should last for minutes.
Without such a memory, analogue operation would be impossible.
1k5 ohm resistors can be used with digital operation to keep the memory alive for longer times when needed.

If the capacitor runs empty, the loco will forget the last direction of travel and will start in the default direction the next time. In the case of a BR 41 this will be smokestack ahead.

Delta forgetfulness should not be an issue with the setup described here as it should occur only if the loco was off power for many seconds.


Unless the capacitor is malfunctioning?
Ray
Mostly Marklin.Selection of different eras and European railways
Small C track layout, control by MS2, 100+ trains but run 4-5 at a time.
Offline H0  
#13 Posted : 04 October 2019 17:12:14(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 13,505
Location: DE-NW
Originally Posted by: RayF Go to Quoted Post
Unless the capacitor is malfunctioning?
For me "decoder Alzheimer" is a design flaw.
Delta decoders working as expected do not have decoder Alzheimer, even if they are forgetful after a few minutes.
Decoder malfunction is a different topic.

If only a single loco has this issue then a decoder defect may well be the reason.
But still this behaviour is not "by design" as I understand the situation described here.

Delta decoders to not have flash memory, but they do have short-term memory for the direction.

There could be something wrong with that single-bit memory or the power supply for that memory - or with the circuit that detects reversing voltages. Or maybe an issue with the layout, especially the shadow-station transformer.

Delta forgetfulness can only be a problem if the BR 41 is run tender ahead - because after a memory-loss it should run smoke stack ahead.
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
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Offline RayF  
#14 Posted : 04 October 2019 17:59:43(UTC)
RayF

Gibraltar   
Joined: 14/03/2005(UTC)
Posts: 15,440
Location: Gibraltar, Europe
Originally Posted by: H0 Go to Quoted Post
Originally Posted by: RayF Go to Quoted Post
Unless the capacitor is malfunctioning?
For me "decoder Alzheimer" is a design flaw.
Delta decoders working as expected do not have decoder Alzheimer, even if they are forgetful after a few minutes.
Decoder malfunction is a different topic.

If only a single loco has this issue then a decoder defect may well be the reason.
But still this behaviour is not "by design" as I understand the situation described here.

Delta decoders to not have flash memory, but they do have short-term memory for the direction.

There could be something wrong with that single-bit memory or the power supply for that memory - or with the circuit that detects reversing voltages. Or maybe an issue with the layout, especially the shadow-station transformer.

Delta forgetfulness can only be a problem if the BR 41 is run tender ahead - because after a memory-loss it should run smoke stack ahead.


I suggested that the problem may be caused by the lack of permanent memory in the delta decoder for the direction information, because I often have similar temporary "memory loss" issues with decoders of this vintage, and never with newer decoders.

In my case it is sometimes triggered by a momentary power irregularity when going over points, when the
loco suddenly reverses direction. When this happens I need to change direction twice to get the loco moving in the right direction again.

This only happens to me with Delta, 6080 and 6090 decoders, and not just on a single loco. It is a rare event in any case and does not usually cause any damage, only perhaps a derailment or two.

I don't consider it a permanent failure of the decoder because the operation is restored perfectly afterwards, and does not recur in the short term, but I do think it is a "weakness" in the design of the decoder.

I have experience in electronics, but without intimate knowledge of the way the decoder works I can only guess at the cause, and my guess is that a spike in voltage is not being properly filtered and the decoder takes it as a command to change direction. Capacitors often decay with time which is why I made the comment about the possible cause being a defective capacitor.

Of course, I could be totally wrong!
Ray
Mostly Marklin.Selection of different eras and European railways
Small C track layout, control by MS2, 100+ trains but run 4-5 at a time.
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Offline hxmiesa  
#15 Posted : 07 October 2019 10:07:04(UTC)
hxmiesa

Spain   
Joined: 15/12/2005(UTC)
Posts: 2,726
Location: Spain
Thanks for the comments, guys!

It got a couple of runs yesterday, after more than a day of stand-still. No problems.
Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
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