Repairing Turnout Motors 74990

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Repairing Turnout Motors 74990

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Drongo		#1 Posted : 15 June 2013 09:27:48(UTC) Retweet
Joined: 03/06/2008(UTC) Posts: 1,264 Location: Sydney, NSW		I don't know if this has been mentioned on the forum before, however, I wish I'd seen this video 6 months ago - it would have saved me some money. I have over 100 turnouts in my layout and most of them are 74990's and I've been having unreliability problems with them, so I decided to swap them to 74991's. As one showed it wouldn't work correctly, I swapped it. After swapping about 30 of them I realised that some of the 74490's were under warranty and I asked Marklin if they would repair/replace them. They said they would look at them and take it from there. As freight from Australia to Germany is expensive, I decided to wait until I had a box full to send them. Then as the box was just about full, I discovered this video, and I thought I'd give it a go. I tried 10 of the 74990's and all but 1 worked perfectly. The 1 that didn't was because I buggered the soldering. Regards Greg
		Take it easy . . . . or any other way you can get it !!!!

7 users liked this useful post by Drongo		Janne75, waorb, MikeR, GSRR, DumbGuy, grnwtrs, Alsterstreek
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Iamnotthecrazyone		#2 Posted : 15 June 2013 10:00:28(UTC) Retweet
Joined: 22/01/2012(UTC) Posts: 1,048		Ok, I wouldn't call it repair more like salvage. I had done it once investigating what the problem was. I am not able to listen to the sound of the video while doing this but you do realise that by fixing it that way without replacing the switches you no longer have the feedback function that will indicate the current state of the turnout?


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eroncelli		#3 Posted : 15 June 2013 10:09:47(UTC) Retweet
Joined: 16/02/2011(UTC) Posts: 124 Location: Bergamo - italy		The video is nice, but problem and solution are well known since long time. New Maerklin version has limit switches with improved performance, but still some problem might arise. Technically speaking, use in analogue mode is still possible, without the switches, provided that the command signal is a pulse and not continuos (in this case the winding would burn by overheating)


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intruder		#4 Posted : 15 June 2013 11:27:13(UTC) Retweet
Joined: 16/08/2006(UTC) Posts: 5,382 Location: Akershus, Norway		I removed the switches completely from my turnout motors, and soldered in a short piece of wire across the terminals. The motors work perfect, but limited switching time is important Edited by user 15 June 2013 19:38:58(UTC) \| Reason: typing error
		Best regards Svein, Norway grumpy old sod
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efel		#5 Posted : 15 June 2013 23:02:33(UTC) Retweet
Joined: 23/02/2005(UTC) Posts: 801		The 74490 end shutoff contact problems (and workaround) has been described on the forum for a long time. Unfortunately, we can read on forums that 74491 suffers the same defect. (maybe less often? difficult to make statistics) Fred


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waorb		#6 Posted : 15 July 2013 15:10:40(UTC) Retweet
Joined: 31/05/2011(UTC) Posts: 868 Location: Brazil		Originally Posted by: youngagain I don't know if this has been mentioned on the forum before, however, I wish I'd seen this video 6 months ago - it would have saved me some money. I have over 100 turnouts in my layout and most of them are 74990's and I've been having unreliability problems with them, so I decided to swap them to 74991's. As one showed it wouldn't work correctly, I swapped it. After swapping about 30 of them I realised that some of the 74490's were under warranty and I asked Marklin if they would repair/replace them. They said they would look at them and take it from there. As freight from Australia to Germany is expensive, I decided to wait until I had a box full to send them. Then as the box was just about full, I discovered this video, and I thought I'd give it a go. I tried 10 of the 74990's and all but 1 worked perfectly. The 1 that didn't was because I buggered the soldering. Regards Greg Hello Greg! Greetings from the other side of the world. First of all, thanks for sharing this solution. Me and my father started a layout here in Brazil 5 years ago, and in this time some 74490 failed. Sometimes just one side, sometimes both sides. The freight from here to Germany isn't so expensive, but the mail roundtrip from Brazil to Germany it's huge (more than 45 days). I had sent almost five or six 74490 two times to Germany (so, ~12 broken pieces), openned problem tickets at Märklin's Customer Service, etc... They always exchanged the 74490 in warranty without questions... No problems with some 74491 until now. Last week I saw your topic with this solution, and applied to 5 another broken 74490. Was amazing simple. This weekend we started to verify each one of our 50 turnouts, and found another 3 with problems in one side of each. All of them was soldered with no more problems. You can see our layout in a video (outdated) I made last year, at the following link: https://www.youtube.com/waorb Thanks again, and congratulations for your layout. It's awesome. Best regards, Walter
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1 user liked this useful post by waorb		Joseph Meiring
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oranda		#7 Posted : 19 May 2014 20:03:49(UTC) Retweet
Joined: 21/04/2014(UTC) Posts: 122 Location: ENGLAND		I followed the video above and managed to get 3 out of 3 point motors working again. I am very pleased :-) As they were only a few months old and postage would make it mad for me to post them to Märklin in Germany for repair. Even from the UK! If I buy any more of these motors - I think I will do the modification at the outset The bolt that is thrown across seemed to be very slack in the assembly Just what do the micro switches do ? Thanks for a great tip.
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1 user liked this useful post by oranda		Joseph Meiring
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