the pickup shoe is fixed by a spring and there is a 21 pin ESU lokpilot FX decoder



As soon as possible I will disassemble the coach to see how the pcb is made, and possibly to connect the unused function outputs for cabin and interior lighting.

regards

Disassembling the coach was easy. It's basically a DC coach, wheels are isolated, the two copper tapes connecting the wheels are isolated.

The copper spring in the centre is connected to the slider.
This is the bottom side of the pcb, you can see the three pads for contacting the springs. I guess it's the same pcb for AC and DC.

Connections between wheels, slider and decoder are on the top side of the pcb, two solder joints you can see in the red circle

I suppose that in a DC coach these are missing.
Hope this helps

regards

Mario

Thanks for the excellent info, Mario.

I do have both AC and DC versions.

They are highly similar

Bottom: DC version with 21-pin analog dongle


Solder bridges, DC (left) - AC (right)

My AC version came with a fully functional LP v2 DCC

Apparently with standard factory programming including F4 direct control - only FLf/FLr are required

Thanks gents! The level om friendship and support is simply incredible on this forum!

Image of my board is attached- it would appear the only difference is that AC solder bridge in the corner? (which may or my not be a nightmare to alter...) If that is the case, this should be cake after the solder redo. A marklin 7175 slider fits perfectly, and I can run a wire from the slider to the center tab underneath the PCB.

Or- perhaps still use the outer positive and negative leads underneath the board, and run the pickup shoe to one of those after cutting the copper tab underneath? (therefore negating the need to do some risky soldering on the board? I'm not sure if this method can work- the board electronics are too complicated for me!

From there pop on the 21 pin decoder and I'm set!

A few issues to be considered – partly interrelated:

1. The DC version has wheel pickups at both bogeys. The AC version has wheel pickups at the far end only, not at the cab end. That’s why the AC version requires the long copper strips to provide mass/wheel contact from the far end bogey to the cab end. In the DC version, those strips are without use, as each bogey has wheel/mass contacts.

2. If you mount a pickup shoe on the DC bogey, you may want to check whether the slider can sit on top of the wheel contacts without shortcut, or you may need to remove those DC wheel contacts. If removed, you will need to rely on the far end for mass contact, and keep the long strips intact.

3. Are you planning to replace the DC axles by AC versions? If retaining the DC wheels, you want to interconnect both long strips by a piece of wire at any place, to improve mass return and to enable detection by contact track. If you need to remove the cab end wheel contacts to mount the pickup shoe, be sure to mount AC axles, otherwise the cab end won’t be detected by contact track.





4. Either method would work. The pcb leads just connect the pickups to pins 21 (black) and 22 (red) of the decoder connector.
As far I can deduct from your pics, this is a simple draft of the pc boards.


DC version: the right-sided R+ wheel contact is connected to pin 22 (red/+) through the vertical solder bridge. The left L- wheel contact connects directly to pin 21 (black/-)

AC version: The slider connects to pin 22 (red) through the upper horizontal solder bridge. The right-sided R+ wheel pad now is linked to the left L- pad through the lower horizontal solder bridge and to pin 21 (black).

If you would opt for option 1 – soldering the slider lead to the middle slider pad on the pc board, you will need to make the AC solder bridges, and make sure to completely remove the vertical DC solder bridge (otherwise, the right track would shortcut to the slider).

If you would go for option 2 – cut the long copper strip, this should be done at the R+ side, and leave the L- strip connecting to pin 21 intact. In this case, the slider lead should connect to the R+ pad, and the DC solder bridge should remain intact. In this scenario, you may want to remove the cab end wheel pickups, to prevent these from touching the R+ strip you will be using for slider connection.

Edited by user 16 June 2018 20:04:35(UTC)  | Reason: typo

Ok, job not quite done but lots of progress tonight. I opted to alter the circuit board, and not the car itself. The soldering job went smoother than I thought, and the PCB is now ready. Images below of the board with old solder removed, and then with my new joints:

I then got the 7175 slider test-mounted and it seems to be a perfect fit. I drilled the hole in the chassis and ran the wire inside the car for the center rail power.

Mechanically, the factory DC wheels have an insulated coating on the axles, which means the 7175 will not short out. I've also re-gauged them to the Marklin 13.8mm spacing. All is ok, although I did run a wire across both long copper strips for better ground connection like Bart mentions. Images are below of the feeder wire and pickup shoe, although the mounting is not permanent yet. I hope to get to that tomorrow night.

Mario- excellent idea on the capacitor. I may try and fit one in....

Thanks so much for the help! I've ordered the decoder as well.

Edited by user 15 June 2018 16:13:38(UTC)  | Reason: Not specified

I'll just solder the wire, no money or effort + a more reliable electrical contact anyways

Hi everyone,

All set! Only problem is I don't have the decoder to test it Hopefully that arrives soon enough, my dealer had to special order the ESU one. I don't think I can test it in analogue, since the decoder attachment that came with it (image #3 below) was for DC?

Some images are below, the pickup shoe took some guessing. The screw that holds the truck/wheels in cannot be too tight otherwise they cannot rotate/turn around curves. This means you cannot tighten the pickup shoe if mounted the way I show in the earlier post images. The secondary problem was that arrangement left the pickup shoe without enough spring/pressure against the center rail. The easy solution to all of this was cut two small strips of .015 styrene. I used testers orange tube glue to mount styrene-pickup shoe board. Then for the other side, I used plastruct plastic weld (a must-have for any modeller) to "weld" the styrene to the bogie. Two problems fixed with one solution!

Images below. The more I wait for the decoder, the more I'm thinking about adding LED lighting to the whole train. (the circuit for which I've been working on, and I think I can do it for about $2/car beyond the initial car. Full forum post to follow). In this case the lead car already has the decoder and everything, so why not? If I get the time before the decoder arrives I may convert the set.

Mario- for the LED's, did you use the 12v DC strips? If so, did you need resistors or anything from the decoder to the lights?

Images below! Fingers crossed it all actually works though...

Thanks Bart! That confirms my query then- did you need resistors to get the power to 12v DC for the LEDs, or was the output from the FX decoder sufficient as-is?

I was inspired by this thread to convert my own L388885 (AC version) - I replaced the LP2dcc by an LP3fx and interior lights.
As the decoder board has no function outputs, I soldered wires to pins 15 and 16.


check the 1kΩ resistor

I have added a connector for the other cars

Ebay seller Ledbaron (there may be others): ledbaron connectors Ebay

Hi- I used the fohrman tools. They sell everything you need! https://www.fohrmann.com/de/

Hi everyone,

An update on this (near completed!) project:

I [u]finally[u] received the accesory decoder in the mail, which of course popped right in and all is working! Well, almost...

So the lighting on the coach is opposite that of the locomotive. Meaning when the loco shows forward lighting the coach shows reverse. Now I realize I could just turn the locomotive around, but I thought I'd ask: is there a way to program the accessory decoder for this? (meaning reversing the lighting?) One thing I didn't check was whether the locomotive lighting was wired backwards. I'll have a peek at that tonight.

More importantly, a nightmare has arisen in the meanwhile: one LED for the reverse red lighting has fallen off the PCB somehow. if I hold it in place with a pair of tweezers it does still work, but does anybody have a clue how to reattach this? It doesn't look soldered on to begin with, and its a scary looking job regardless!

Once I sort the light reassembly out I'll post images of the full set!

I thought abut glue- but does superglue conduct electricity?

For the reversed lights: set CV 29 bit 0 to 1, and the direction will be opposite.
Cheers
Jacques

As for the other half of the battle: this is SMT ( Surface Mount Technology)
Very carefully heat, with super fine soldering iron and just a tiny drop of solder tin as heatsink, at the "loose" end of the component and gently press the LED on the PCB and maintain pressure for a few seconds until it cools off.
Normally the solder goes from shiny (hot/flowing) to dull (cold/hard)
Use magnifying glass to observe , it's indispensable!
Used to do this a lot when assembling and testing the first Bluetooth radio prototype boards 20 years ago, but I don't have the steady hands no more!
Good luck
Jacques

Hi everyone, I'm reviving this thread as I get into the project.

@bart: if you don't mind my asking, are you running capacitors at all? If not, are you getting flicker?

I think my plan is a circuit like yours:

Lokpilot FX - 1k ohm resistor - LED strip - (coach connection), then repeat from car to car. Only question mark being a capacitor (or capacitors per car)

A question for the wiser electronic minds that my own: does it matter how many cars I connect on this circuit? Or would that impact the resistor values? I suspect not, and all additional cars would do is put more draw on the decoder?

Thanks Bart! This is much easier with decoder than the circuit I was building from direct track current. (although that I will still use in most consists)

I ordered a variety pack of resistors on ebay, so once they show up I'll get to work and report back!