Welcome to the forum   
Welcome Guest! To enable all features please Login or Register.

Notification

Icon
Error

Share
Options
View
Go to last post in this topic Go to first unread post in this topic
Offline Johnvr  
#1 Posted : 17 May 2017 19:20:41(UTC)
Johnvr

South Africa   
Joined: 03/10/2010(UTC)
Posts: 1,269
Location: Cape Town, South Africa
Hi all,

Yesterday I fried a 60945 Marklin Sound Decoder for Steam Locomotives Angry Angry Angry

My friend Joe had come over and we were installing a 60945 MSD in his Steam Loco.
The loco was running up and down the track, and we tested all the lights on the decoder. Everything was working.
We then put some smoke fluid into the smoke stack and turned the smoke unit on.

Suddenly the CS2 went on the blink, the decoder started burning and smelling, and it was all over in a second.
The decoder was well and truly fried, and the decoder now only burns and lets off smoke if we connect it again.
I suspect that the smoke auxiliary function touched a ground somewhere on the chassis, and short-circuited the decoder.

Which has got me thinking about installing a fuse.
I am thinking about installing a fuse between the CS2 and the Track.
After all, blowing a fuse is much less expensive than blowing a 60945 or a CS2 even.

Do you think that blowing a fuse would have prevented the decoder from burning out ?
Why didn't the CS2 detect the excessive amperage and shut down before the decoder burned out ?
If you think it is a good idea to install a fuse, what rating should the fuse have ?

I'd like to get your thoughts please.

Regards,BigGrin
John



thanks 2 users liked this useful post by Johnvr
Offline Webmaster  
#2 Posted : 17 May 2017 19:44:31(UTC)
Webmaster


Joined: 25/07/2001(UTC)
Posts: 11,161
How about the decoder controlling a relay that connects the smoke unit to track power & chassis ground instead?

Since you don't give any info on the loco model or motor setup, it's hard to know why it happened.
Normally there are protective diodes to prevent decoder burnout, and I thought mSD would have that just like ESU...
Juhan - "Webmaster", at your service...
He who asks a question is a fool for five minutes. He who does not ask a question remains a fool forever. [Old Chinese Proverb]
thanks 1 user liked this useful post by Webmaster
Offline RayF  
#3 Posted : 17 May 2017 20:01:00(UTC)
RayF

Gibraltar   
Joined: 14/03/2005(UTC)
Posts: 15,838
Location: Gibraltar, Europe
Decoders are sensitive pieces of electronic equipment. I've blown several over the years whenever I've failed to take proper care with my wiring and connections. This is usually caused by me being in a hurry to finish the conversion and not checking everything properly.

It doesn't take long for a decoder to fry if voltage or ground is applied to the wrong part of the circuit. The damage is usually done in milliseconds and in my opinion a fuse would not have even started getting warm in this time.

Apart from the motor the biggest consumer of current in a loco is a smoke generator. For this reason they are often connected through a relay as Juhan has suggested above. In John's case either the decoder output was insufficient to handle the current draw of the smoke unit or the function wire to the smoke unit was shorted somehow. The relay would have helped here.

I don't think a fuse between the CS2 and the track would protect the decoder, though it could well add a level of protection to the CS2. You state that the CS2 started "going on the blink". This would be the over-current protection kicking in, so that at least did work well.



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.
thanks 4 users liked this useful post by RayF
Offline Johnvr  
#4 Posted : 17 May 2017 20:24:16(UTC)
Johnvr

South Africa   
Joined: 03/10/2010(UTC)
Posts: 1,269
Location: Cape Town, South Africa
Originally Posted by: Webmaster Go to Quoted Post
How about the decoder controlling a relay that connects the smoke unit to track power & chassis ground instead?

Since you don't give any info on the loco model or motor setup, it's hard to know why it happened.
Normally there are protective diodes to prevent decoder burnout, and I thought mSD would have that just like ESU...


Juhan,

It was Joe's Marklin 37015 , the K. Bay.Sts.B , green loco with two large drive wheels.
It comes fitted with a 21-pin plate in the Tender, with the decoder on the plate.
The Smoke Unit came separately and one needs to remove the body to install the smoke unit manually.
There is no possibility of a relay in this case.

Regards,BigGrin
John

thanks 2 users liked this useful post by Johnvr
Offline JohnjeanB  
#5 Posted : 18 May 2017 16:18:34(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 3,083
Location: Paris, France
Hi John and friends

I had in the past a short between one output and the ground and the decoder 60645 I think swichted itself off and restarted. On another one it fried after many hours of operation. So there is a protection but it is far from being 100% effective😳
Now i have to buy more at 73 euros (60945) and it does not look the price will go down soon.
Cheers
Jean
Offline Goofy  
#6 Posted : 18 May 2017 19:02:47(UTC)
Goofy


Joined: 12/08/2006(UTC)
Posts: 8,993
Originally Posted by: Johnvr Go to Quoted Post
Originally Posted by: Webmaster Go to Quoted Post
How about the decoder controlling a relay that connects the smoke unit to track power & chassis ground instead?

Since you don't give any info on the loco model or motor setup, it's hard to know why it happened.
Normally there are protective diodes to prevent decoder burnout, and I thought mSD would have that just like ESU...


Juhan,

It was Joe's Marklin 37015 , the K. Bay.Sts.B , green loco with two large drive wheels.
It comes fitted with a 21-pin plate in the Tender, with the decoder on the plate.
The Smoke Unit came separately and one needs to remove the body to install the smoke unit manually.
There is no possibility of a relay in this case.

Regards,BigGrin
John



Check if copper plate contact for the smoke generator did not touch the body of smoke generator.
Maybe you did install smoke generator wrong?

H0
DCC = Digital Command Control
Offline Minok  
#7 Posted : 18 May 2017 22:29:10(UTC)
Minok

United States   
Joined: 15/10/2006(UTC)
Posts: 2,310
Location: Washington, Pacific Northwest
The controllers already have short circuit protection in case the track power is grounded short, but that likely would not have helped in your case. Adding a fuse to the to-track power feed isn't usefull as the MS/CS/etc already have circuits to provide that protection as they monitor the current.

In your case, the output or power stages of the decoder board likely cooked off. It may well be a short from the smoke function output line to the body. You would have needed a fuse between that output and the smoke generator, and even then you would have to take care that you install the fuse correctly without a short before the fuse.. so there's still an opportunity to mess the fuse install up.

The power stages of the decoders can only handle a limited current and would fry long before the MS/CS likely could ever detect a short.
And then it could have been a board level failure to the smoke generator output lead (f1?).. a defect in the board. Of the contact was some how grounded via a screw, etc.

The best solution is just handle the decoders wisely (ground yourself first to dissipate static), be deliberate and slow in the work you do (don't rush or skip visual checks), and you can use a multimeter/tester to check outputs are not grounded before applying power if your paranoid.

But fuses, I don't think would have helped in this case unless it was a precisely specified fuse installed just on the smoke generator output and installed correctly and there wasn't an issue ON the decoder board or how it was contacting the body of the loco. The fuse only protects against things that are bad AFTER the current gets through the fuse.
Toys of tin and wood rule!
---
My Layout Thread on marklin-users.net: InterCity 1-3-4
My YouTube Channel:
https://youtube.com/@intercity134
Offline rugauger  
#8 Posted : 19 May 2017 16:14:05(UTC)
rugauger

United Kingdom   
Joined: 19/12/2003(UTC)
Posts: 1,205
Location: Swindon, Wiltshire
Originally Posted by: Minok Go to Quoted Post

...
The best solution is just handle the decoders wisely (ground yourself first to dissipate static), be deliberate and slow in the work you do (don't rush or skip visual checks), and you can use a multimeter/tester to check outputs are not grounded before applying power if your paranoid.
...

+1 for the multimeter! And use of it is mandatory, not paranoid Wink My boss always says: "check, check and check again"...
I agree that a fuse would not have helped since its "reaction time" would have been too long in any case.

Perhaps next time install the smoke generator and then before you wire it up to the decoder, test its function with an analog transformer first by simply holding a wire to the connector. Then, once you're happy there is no short, connect to the decoder and check everything with a multimeter.

Finally, are you sure there is no place in the tender for a relay? You can get miniature relays with a very small footprint these days.
Richard
Offline DaleSchultz  
#9 Posted : 20 May 2017 00:06:14(UTC)
DaleSchultz

United States   
Joined: 10/02/2006(UTC)
Posts: 3,997
bummer of an experience for sure.

Have installed relays for smoke units, for example in my 3048
http://cabin-layout.blogspot.com/2004/02/installingdigitaldecoder.html

But the relays I obtained are really designed for 12 Volts, and I think the decoders put out more than 12V.

What relays have others used?

Edited by user 20 May 2017 03:44:59(UTC)  | Reason: typo

Dale
Intellibox + own software, K-Track
My current layout: https://cabin-layout.mixmox.com
Arrival and Departure signs: https://remotesign.mixmox.com
Offline mario54i  
#10 Posted : 20 May 2017 18:19:36(UTC)
mario54i

Italy   
Joined: 28/03/2007(UTC)
Posts: 283
Location: Torino,
Miniature solid state relays are quite effective for moderate currents, say to 1 A.
This is an example
http://www.mouser.it/Pro...JKYUEHNj3mgE1OnoxQ%3d%3d
Besides being much smaller than conventional relays, even miniature ones, the input drive is an LED, it works at 5 - 10 mA max. It could in principle be driven even by logic level decoder outputs.
Just be aware that output is not a mechanical contact, it's a transistor, it can't bear high overload even for short time.
Offline H0  
#11 Posted : 20 May 2017 19:05:42(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Originally Posted by: mario54i Go to Quoted Post
It could in principle be driven even by logic level decoder outputs.
According to NEM 660 the permitted load on logic level outputs is 0.5 mA.
Unless your decoder permits a higher load, you still have to add a transistor to drive that "solid state relay".

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
UserPostedImage
Offline DaleSchultz  
#12 Posted : 20 May 2017 20:45:11(UTC)
DaleSchultz

United States   
Joined: 10/02/2006(UTC)
Posts: 3,997
Originally Posted by: mario54i Go to Quoted Post
Miniature solid state relays are quite effective for moderate currents, say to 1 A.
This is an example
http://www.mouser.it/Pro...JKYUEHNj3mgE1OnoxQ%3d%3d
Besides being much smaller than conventional relays, even miniature ones, the input drive is an LED, it works at 5 - 10 mA max. It could in principle be driven even by logic level decoder outputs.
Just be aware that output is not a mechanical contact, it's a transistor, it can't bear high overload even for short time.


Thanks, that looks very interesting. I assume that one would then include a resistor on the function output of the decoder to ensure that the current is limited to 10mA. I think the load should stay well below 1A for a single smoke unit. I guess one could put a diode in the load side so that it chops half the digital current if there is a chance a smoke unit will exceed 1A.

I wonder how hot the relay gets?



Dale
Intellibox + own software, K-Track
My current layout: https://cabin-layout.mixmox.com
Arrival and Departure signs: https://remotesign.mixmox.com
Users browsing this topic
Forum Jump  
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

| Powered by YAF.NET | YAF.NET © 2003-2024, Yet Another Forum.NET
This page was generated in 0.705 seconds.