I got green LEDs as replacement for my vintage marklin 7188 signals. They work fine in analog mode with classis 4-button switch box.
The leds do not work when signal is powered from a k83 decoder in my digital layout. Surprisingly, lights works when switching yellow current and signal ground connections. However, then the solenoid does not get power, so no pulse switch.

The led bulbs are not polarity sensitive and work fine when fed from digital track power. The k83 decoder connection somehow changes the nature of current out to yellow plug.

What is happening? Is there a solution?

Ben

The k83 uses DC for its internal electronics, and switches that to drive the solenoid in the signal. So the signal solenoids should work correctly. However the bulb relies on a connection back to the rails for its return path. You may need to make a connection from the signal base plate to the brown track connection on the k83 if you are using C track or K track, or don't have the signal base plate clamped to M track.

Hi Jean, I took a look at the ebay listing. It says the LEDs are EUR 10.74 a pop!
(Aside from the listing saying "the seller does not ship to Canada")
That would make almost more worth it for me to buy newer signals

What about soldering new tiny LEDs oneself or rewiring the lights from the signal as Alan suggests?
- Mark

Hi Mark
You are right, my example the LED was right but the price was wrong.
Here is the same article, same price but for a quantity of 5
https://www.ebay.de/itm/25486788...f55ae:g:MH8AAOSwER1gKW7i
This is the price you must be prepared to pay to forget about changing bulbs and reducing drastically the current drain
On my layout, except on the decoupling masts all bulbs are gone (trains, signals, switches, houses, etc)
To be noted: some LED replacements are really "shitty" like the Viessmann LED bulbs E5.5. Very often, the LED is not attached to the socket and can get destroyed easily
Cheers
Jean

I did some testing and found the answer: this particular LED
https://www.ebay.com/itm/294482539108?var=593044434873

The green LED is polarity sensitive when powered from DC source, with current to bottom of LED.
The green LED works with standard AC power (yellow, brown) from white transformer, regardless of polarity (switching wires).
The green LED works with digital AC power (red and brown) from CS3, regardless of polarity (switching wires).
The green LED connected to k83 decoder (yellow current wire and brown ground) only works when brown connects to bottom of led (current), instead of yellow. So now it is polarity sensitive, just like DC transformer source, but with ground as lead. A yellow-brown wire switch does not activate the solenoid, obviously, which requires normal yellow current and brown ground.

I have white LEDs from another supplier and they work fine in all setups (incl normal yellow-brown from k83), and are also not polarity sensitive in DC.

Thus, the green LEDs are polarity sensitive from k83, like they are from the DC source, except that the wires are now switched. The white LEDs are not DC polarity sensitive, so yellow-brown wire to LED does not matter, which provides a quick test for suitable replacement bulbs.

Now contacting vendor and ask what they suggest, since these are advertised as Marklin bulb replacements.

Hi Ben,
The seller from the link you provided does not ship to Canada, according to the listing.

Was that the vendor you were contacting, and did you manage to get them shipped to Michigan?

- Mark

Edited by user 14 May 2022 20:20:21(UTC)  | Reason: Not specified

The ebay vendor told me that this issue has not reached them before.
My use is specialized, though all Marklin gear (7188 + k83). The bulbs work great in analog AC and digital AC, which is their typical use. The k83 produces a polarity switched DC signal (why?) that these LEDs don't support (I tested with several k83 units).
Perhaps the vendor will include this property, as other LED replacement bulbs do not have a DC polarity restriction.