 Joined: 10/02/2006(UTC) Posts: 3,997
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 1 user liked this useful post by DaleSchultz
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Joined: 10/02/2006(UTC) Posts: 3,997
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any comments on the LEDs they use, could they be two connected anti-parallel? |
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 Joined: 21/05/2004(UTC) Posts: 1,768 Location: Brisbane, Queensland
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You might want to update the topic, the lanterns are item 7547. In regards to your question, I have installed a number of these but I am yet to connect them to power. I had originally planned to connect them to my DC power. I have taken a look at the manual and it says AC/DC power, so it seems either is fine. I have not looked at the circuitry for the LED's but Marklin may use a 4-way bridge rectifier for the AC (no affect DC). https://static.maerklin....dcddcdcc461464615060.pdf |
modelling era IIIa (1951-1955) Germany |
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Joined: 10/02/2006(UTC) Posts: 3,997
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Thanks, I fixed the typo in the topic title.
From what I described in the internals I do not think they are rectifying the power. If that was the case there would be just a single LED. A second LED is probably cheaper than a rectifier or 4 diodes. |
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Joined: 21/05/2004(UTC) Posts: 1,768 Location: Brisbane, Queensland
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Old topic but wanted to add my experiences here. So after wiring up all of my 7547 lanterns to power, I found that 2 out of ~24 did not work. I only had 1 spare lantern so I had to open them up and repair. The circuitry is very basic. There are a pair of 3.9K ohm resisters and a pair of LED's, wired in parallel and opposite polarity to each other. No bridge rectification. This means the lanterns would work in either AC or DC, though with DC power only one LED would be lit. With AC power, both LED's are lit as they each use half of the AC wave. Now onto why my two lanterns were dead. Very simple to fault find because the only possible cause of a no lighting is if one of the resisters is open circuit - and that means the entire circuit is. My multi-meter confirmed that in both lanterns, one of the two resistors was showing open circuit. I found it unlikely that the resistors were faulty though and so by re-positioning my multi-meter probes to the very top edge of the resistors, they then test OK. This means for some reason the solder to the resistors is not providing electrical connectivity. I then re-soldered the resistor contact points generously to ensure good electrical connectivity. I re-tested with my multi-meter again from the wire through to the LED and I now see correct 3.9K ohm for both - fixed!  |
modelling era IIIa (1951-1955) Germany |
2 users liked this useful post by applor
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Joined: 10/02/2006(UTC) Posts: 3,997
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good job!
thanks for confirming it is two LEDs connected anti-parallel.
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1 user liked this useful post by DaleSchultz
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 Joined: 04/04/2013(UTC) Posts: 1,291 Location: Port Moody, BC
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I had a similar experience. Out of the numerous 7547 lanterns that I installed, one did not work. I opened it up and one of the resistors actually fell out. Of course I tried to pick it up with my fingers and being as small as it is it immediately flew off into the room never to be found again. I ordered a strip of 50 on eBay for less than $2 and once they arrived, a new solder job fixed the problem. Since then no others have failed and I have a lot of resistors left over!
Peter
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1 user liked this useful post by PMPeter
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Joined: 04/04/2013(UTC) Posts: 1,291 Location: Port Moody, BC
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Reviving an old topic.
Nearly all of the 7547 lanterns that I have are manufactured with the 2 LEDs as shown in a previous post. I have now opened a new package and one of the lanterns was very dim. To my surprise the 2 LEDs have now been replaced by a single large SMD LED. The 2nd lantern from the same package was constructed the same way with the large single LED but was bright as usual. So I assume these larger SMD LEDs consist of 2 LEDs in anti-parallel construction and that in the one lantern one of these LEDs is not functioning. Has anyone else discovered this and does anyone know what this SMD LED part number may be?
Peter
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