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Offline PMPeter  
#1 Posted : 05 June 2019 22:27:00(UTC)
PMPeter

Canada   
Joined: 04/04/2013(UTC)
Posts: 953
Location: Port Moody, BC
Does anyone know the specs or diode type for the Viessmann 5211 switch decoder? Diode D12 suddenly let out the magic smoke last night while I was working on a totally different area of the layout.

Burnt diode


I might be able to get a partial number off of it when I unsolder it from the board, but part of it is gone if I compare it to diode D2.

Thanks
Peter
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Offline Purellum  
#2 Posted : 05 June 2019 22:47:02(UTC)
Purellum

Denmark   
Joined: 08/11/2005(UTC)
Posts: 3,021
Location: Mullerup, 4200 Slagelse
Cool

Just guessing, it looks very 1N4001-ish BigGrin

Maybe you could unsolder D2 and see it you can find the numbers on that, or if you have other 5211s, have a look at them.

Per.

Cool
If you can dream it, you can do it!

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Offline French_Fabrice  
#3 Posted : 05 June 2019 23:08:32(UTC)
French_Fabrice

France   
Joined: 16/05/2011(UTC)
Posts: 1,195
Location: Lyon, France
Hello Peter,

I don't own 5211, but I've built many 5291 (kit to solder, no more for sale).
Looking at the schema, the diode D12 is 1N4936.

However, the schema is not exactly the same as your photo, but there is good hope...
I provide the doc of the 5291.
https://www.marklin-users.net/up...e/3436_viesmann-5291.pdf

Cheers
Fabrice
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Offline DaleSchultz  
#4 Posted : 05 June 2019 23:19:22(UTC)
DaleSchultz


Joined: 10/02/2006(UTC)
Posts: 2,994
pretty sure a 1N400x would do the trick...
Dale
Intellibox + own software, K-Track
My current layout: https://cabin-layout.mixmox.com
Arrival and Departure signs: https://remotesign.mixmox.com
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Offline Purellum  
#5 Posted : 05 June 2019 23:31:11(UTC)
Purellum

Denmark   
Joined: 08/11/2005(UTC)
Posts: 3,021
Location: Mullerup, 4200 Slagelse
Cool

Originally Posted by: DaleSchultz Go to Quoted Post
pretty sure a 1N400x would do the trick...


So am I; but apparently the 1N4936 is a faster diode.

A lot of replacement possibilities though: https://www.el-component.com/diodes/1n4936

Per.

Cool



If you can dream it, you can do it!

I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide.

In case this is not legally possible:
I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.

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Offline DaleSchultz  
#6 Posted : 05 June 2019 23:47:17(UTC)
DaleSchultz


Joined: 10/02/2006(UTC)
Posts: 2,994
I agree, looks to be 1N4936
Dale
Intellibox + own software, K-Track
My current layout: https://cabin-layout.mixmox.com
Arrival and Departure signs: https://remotesign.mixmox.com
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Offline Hannes Porsche  
#7 Posted : 06 June 2019 00:00:27(UTC)
Hannes Porsche

South Africa   
Joined: 08/12/2015(UTC)
Posts: 27
Location: Western Cape, South Africa
Hi Peter, sorry to see such damaged product.

D12 certainly was subjected to severe overcurrent in the forward direction, more than 1,0 Amps. Alternatively subjected to severe reverse voltage exceeding 50 Volt ( 1N4001).
If the current was supplied by C 2 or from there around, the copper tracks underneath, and feeding D12 should also have cooked. See if track discolouring has occurred.
So replacement of the diode by say 1N4005 or higher will be OK.

Sorry I do not know Viessmann products, but looking at the third terminal on the above PCB there may very well have been a real problem that was connected to it.
It would be wise to check those items connecting to the "output " terminals.
Chances are good an external fault is the origin of the problem.

Hope you manage,

HANNES VAN ZYL

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Offline PMPeter  
#8 Posted : 06 June 2019 01:26:39(UTC)
PMPeter

Canada   
Joined: 04/04/2013(UTC)
Posts: 953
Location: Port Moody, BC
Thanks everyone.

I have some 1N4935 diodes which are what I needed to repair a K83 a few years ago. Not sure what the difference is between a 1N4935 and a 1N4936?

Anyway it puzzles me why it failed since it controls uncouplers in a switch yard that I have not operated in at least a year. Testing the uncouplers did not reveal any problem, but this yard is my brittle C track yard that to a large degree is held together with glue. If I try to take the uncouplers out for a better look inside, I will end up with a cup full of broken C track connectors. So for the price of a diode I think I will repair the decoder and give it another try. If that diode blows then I know another chunk of C track and switches will end up in the garbage.

Hardly any trace of damage below the PCB. So a little careful cleaning should be all I need.

Peter
Offline Purellum  
#9 Posted : 06 June 2019 08:31:38(UTC)
Purellum

Denmark   
Joined: 08/11/2005(UTC)
Posts: 3,021
Location: Mullerup, 4200 Slagelse
Cool

Originally Posted by: PMPeter Go to Quoted Post
Not sure what the difference is between a 1N4935 and a 1N4936?


1N4935 is rated to 200 V, and 1N4936 is rated to 400 V.

In this case it shouldn't matter which one you use.

https://www.vishay.com/docs/88508/1n4933.pdf

Per.

Cool

If you can dream it, you can do it!

I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide.

In case this is not legally possible:
I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.

UserPostedImage
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Offline Danlake  
#10 Posted : 06 June 2019 11:06:06(UTC)
Danlake

New Zealand   
Joined: 03/08/2011(UTC)
Posts: 1,409
I once fried a diode as well in my Viessmann 5211 switching decoder.

The decoder was wired up to digitally control a Marklin M track turnout and it happend when I accidentally made a shortcut (layout was powered) while trying to change the bulb for the turnout...

Best Regards
Lasse
Digital 11m2 layout / C (M&K) tracks / Era IV / CS3 60226 / Train Controller Gold 9 with 4D sound. Mainly Danish and German Locomotives.
Offline Bigdaddynz  
#11 Posted : 08 June 2019 08:29:10(UTC)
Bigdaddynz

New Zealand   
Joined: 17/09/2006(UTC)
Posts: 16,566
Location: New Zealand
I suspect Peter has a 5291 K83 given the component markings on the circuit board. I made up a few of these about 12 years ago and I recently picked up another one from some items our club was selling.

In the instructions, D12 is listed as a 1N4936 (I see Fabrice already answered this question in his post).

I mentioned in another thread a few months ago that I had been greeted by some electrical smells when powering on my layout after a few months of not using it. Turned out it was a 5211 that cooked - you can see the component just above the DIP switch has cooked (not sure what it is) and the capacitor to the left has popped its lid.

You can see similar components in behind the large transistors.

IMG_20190608_181619.jpg
Offline PMPeter  
#12 Posted : 08 June 2019 16:25:11(UTC)
PMPeter

Canada   
Joined: 04/04/2013(UTC)
Posts: 953
Location: Port Moody, BC
My decoder shows 5211 on the cover.

I replaced the diode and had to add some jumper wires on the back since the 2 soldering pad leads were damaged and would not accept any more solder even after scraping off the varnish.

It is back in place and all the devices are connected back in and working fine. Still puzzled why this would suddenly fail in an area not being used for quite awhile. I believe this is one of the units I bought on eBay a few years ago and it may have been over-stressed by the previous owner and suddenly failed.

Anyway for now it is back in operation.

Peter
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Offline Bigdaddynz  
#13 Posted : 08 June 2019 23:08:12(UTC)
Bigdaddynz

New Zealand   
Joined: 17/09/2006(UTC)
Posts: 16,566
Location: New Zealand
Originally Posted by: PMPeter Go to Quoted Post
My decoder shows 5211 on the cover.


Yes, they all do including the 5921's.
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