Hello,
Does anyone have experience converting to LEDs on older locos? I've managed to remove the incandescent bulbs on my 1970s BR 103 (#8854) and solder on rice-grain LEDs with tiny resistors. Upon testing, the new lights are unreliable. Sometimes the wrong end lights up (the rear lights up while moving forward and vice versa), sometimes the LEDs are very dim or don't light up at all... I seem to have missed something.

Is that a capacitor on the circuit board? Does it have anything to do with the lights?

Thanks!

Märklin's diodes from the 70's are starting to fail. I have two early 8875's where diodes have failed closed circuit, causing the bulb to be illuminated in both directions.
Perhaps they can't be relied upon for controlling you leds.

In any case you need to confirm the polarity of the diodes on the circuit board correspond to the leds

To answer the easy bit first, the capacitor helps stop the LED from flickering, which can be particularly bad if your track/wheels are dirty

To get to the more complicated stuff (and apologies if what I say here is patronising - seeing as you've got this far you may know most of this already).

LEDs are directional devices, which is to say they'll glow when the voltage is applied in one direction, but not the other. This may answer your observation that some LEDs light up in the wrong direction of travel. In this case, flip the LED round and you should be in business.

Locomotives with directional lighting will have a diode on the board to control the flow of current to the incandescent bulbs. These are quite susceptible to damage so the best thing is to remove them altogether and link them out. On diesel locomotoves these are the small disc things at eaither end of the circuit board. It's easy enough to unclasp the metal clip that holds them in place, memove the disc diode and then replace the clip, making sure it makes contact with the central contact point on the PCB. Once that's done your LEDs will take care of themselves regading directional lighting up.

If the disc diodes are still fitted but in opposition to your LED, the LED won't light up. Flipping the LED round will sort this out, but I would also recommend getting rid if the diode which does nothing useful now and only delays the point at which the LED lights up.

As for varying brightness, different colour LEDs need different levels of current - a white or blue LED can be blindingly bright with just a few hundred microamps, whilst a red or green might need ten times as much. What value resitors have you fitted? I'd suggest something like 1k would be a good starting point for red, green or yellow, whilst 10k or 22k might be better for white of blue.

A final point is that LEDs can be quite sensitive to prolonged heat, particularly the white and blue ones, so if you've been a bit slow with your soldering that might have damaged them. If you have a multimeter you can check them out with the continuity/diode check. Obviously they'll only light up with the connections the right way round, but you can check they do light up this way.

Hope that's of help


Chris

I've seen them on ebay from time-to-time but that's about it.

The difficulty is getting power to from the wheels to the interior of the coach itself. There's no easy way to accomplish this and they all add significant friction to the movement, so your locos will end up being able to pull even fewer coaches.

Cheers


Chris

Do these 'rice grains' exist based on 0402 or 0201 sized diodes? That would be smaller. And is it possible to get them with resistors inside? I wonder what type of resistors you used. You should probably try to avoid the big axial resistors like the ones that came with the leds, and use smd 0402 or 0201 resistors instead. Would it be possible to use the footprints where the mentioned diodes were mounted originally for the series resistors?
Anyway, most of my HO conversions I do with smd 0402 leds and 0603 resitors, I admit I dont do tiny Z.
Br,
Bert

Yes 0201 is small, but to inhale these you really need to make an effort I think. I use these in my work as electronics engineer quite often and I never noticed issues and never felt the need to use masks. You will need a good magnifier, soldering iron and tweezers to use them though, so for this topic, maybe start with 0402 components first.
btw, i recently purchased some warmwhite 0402 leds from a german online shop called 'ledandmore' and i am very pleased with the price and led color.

Parakiet of Belgium loves this topic!

Hi Dwight,

Are you talking about the CK LEDs or a Märklin spare part? If it is Märklin, could you please give us the spare part number?

Thanks,
Carim

Thanks for the information!

I recently talked to ZscaleHobo about these replacement LEDs. I asked if they could be used in non-steam locos (the listing says they are for steamers). I was told that they might work in non-steamers, but there was uncertainty in the answer. Now I know why. It's the thickness of the base!

Having made my own LED replacements for my #8858 BR 103 electric, I would not hesitate to add a layer of solder, as Zme suggests, to make the bases thicker. I doubt a lot can go wrong, but I have yet to buy some and to try this "fix."

Good luck!

Would like to know where my post disappeared that showed the LED replacement??! Was liked by Zme then went?

I've already endorsed adding a thin layer of solder to LED bases, so they fit snugly in some locos. Now it occurs to me that it might be possible to gently bend the contacts on the engine's circuit board to achieve a snug fit. And in cases where the looseness of LED base is extreme, it might necessary to do both: add layers of solder AND put a slight bend of the contacts.

But I don't really know. I haven't yet seen these new Marklin LED replacements, nor the locos in question.

Good luck everyone.

I would be cautious about trying to add solder to build up the thickness. Solder is very soft and will collapse under spring pressure, over time, eventually causing intermittent contact. To build up that sort of thickness I would look at soldering a piece of copper sheet onto the new lamp unit to make it thicker.

I've also been trying to think of something you might have to hand that you could use to bulk up the thickness of the base. The best I can come up with is a sliver of (non aluminium) tin can soldered to the base. A couple of small (M2?) washers might also do the trick. Having said that an off-cut of rail filed flat or a crushed rail joiner would probably also do the trick.

I wasn't initially keen on the idea of a blob of solder - my concern being that it would soon oxidise and possibly lose contact - but I don't think that's likely to be a real problem and worth a try. If it doesn't work it would be easy enough to supplement it with something else.

Any help?


Chris

It's just not possible to solder to aluminium - it oxidises too quickly.

Cheers


Chris

I'm happy to hear that the LED conversion has a solution!

Yes, it would be great if Marklin came out with a direct LED replacement for older locos. Meanwhile, it's not too terribly difficult to remove the incandescent bulbs from their bases and solder on resistor/LED combinations, as I have. And since I learned that even smaller LEDs are available, it will be that much easier to fit the replacements under the body shells.

Chris has informed me that you can't solder aluminum foil. In that event I would attach the foil to the base using a TINY dot of superglue, small enough to still allow for good contact between foil and base. (This assumes you still want to shim the base to make it thicker.)

Cheers y'all!
Sam

I agree that these older locos are worth maintaining and upgrading. I got my #8854 BR 103 Electric in the late 1970s. I cherish it. Now if I could only find the 5-pole motor for it... they're like finding hens teeth!

Sam

Hello, hope all is well.

I agree, those are good pointers for tuning the three pole locomotives and likely these tips are good for a five pole too. Clean, smooth parts are always beneficial.

If I understand correctly, it takes a bit more power to get the 3 pole motor turning, but it has more speed once moving. This motor might be a bit more noisy.

The 5 pole starts to move with less current, might have a bit less speed, but in most cases is quieter. I don’t know why, but put the shell on a Br 110 or similar and there is a growl which you might think is the motor. Perhaps all the gears in the bogies just make noise. Does anyone recall a comparison test of the pulling power of each motor.

Do the basic characteristics of each of these motors influence the performance of a snail controller? Perhaps.

These two motors are long lived, reliable, and likely will be around for some time. Fine tuning is always a good thing.

Take good care.

Zme