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Offline wildstix  
#1 Posted : 02 July 2021 05:22:13(UTC)
wildstix

Indonesia   
Joined: 12/05/2021(UTC)
Posts: 146
Location: Jakarta Raya, Jakarta
Hey everyone in the mini world!

So, I have successfully swapped the trucks of my 8875 loco. It's not running backward anymore and moving much smoother than before.
However, I found another problem. Only one of the lights operating either forward or backward movement. Tried to replace the light, but it's still the same, so I guess the problem is not with the light bulb.
I'm very new in tinkering with the inside of these mini machines, so can anyone suggest me what's wrong with the light system?
Oka aka W. Kapriandi
Märklin Z scale (mini-club) purist but not a modeler!
Offline Zme  
#2 Posted : 02 July 2021 20:45:25(UTC)
Zme

United States   
Joined: 02/10/2013(UTC)
Posts: 760
Location: West Texas
Hi. Hope all is well

You could try swapping the lights. Does it work in the other location?

If the light still doesn’t work, sometimes the tines coming from the circuit board get bent and are not making correct contact. Just carefully bend them to ensure contact is made with the light.

Best wishes

Dwight
Offline Poor Skeleton  
#3 Posted : 02 July 2021 22:34:11(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 550
Location: England, Cambridge
Originally Posted by: wildstix Go to Quoted Post
Hey everyone in the mini world!

So, I have successfully swapped the trucks of my 8875 loco. It's not running backward anymore and moving much smoother than before.
However, I found another problem. Only one of the lights operating either forward or backward movement. Tried to replace the light, but it's still the same, so I guess the problem is not with the light bulb.
I'm very new in tinkering with the inside of these mini machines, so can anyone suggest me what's wrong with the light system?


Between the PCB and bulb contact spring at the end is a tiny disc diode. It's possible contact has been lost to this or perhaps it is faulty. Do you have a multi-meter? It's easy to check out if you do. Alternatively, if you short between the circuit board and the contact spring that will bypass the diode so if the light then comes on you'll know that's where the problem is.

Hope that's of help


Chris
thanks 3 users liked this useful post by Poor Skeleton
Offline wildstix  
#4 Posted : 07 July 2021 14:41:25(UTC)
wildstix

Indonesia   
Joined: 12/05/2021(UTC)
Posts: 146
Location: Jakarta Raya, Jakarta
Originally Posted by: Poor Skeleton Go to Quoted Post
Originally Posted by: wildstix Go to Quoted Post
Hey everyone in the mini world!

So, I have successfully swapped the trucks of my 8875 loco. It's not running backward anymore and moving much smoother than before.
However, I found another problem. Only one of the lights operating either forward or backward movement. Tried to replace the light, but it's still the same, so I guess the problem is not with the light bulb.
I'm very new in tinkering with the inside of these mini machines, so can anyone suggest me what's wrong with the light system?


Between the PCB and bulb contact spring at the end is a tiny disc diode. It's possible contact has been lost to this or perhaps it is faulty. Do you have a multi-meter? It's easy to check out if you do. Alternatively, if you short between the circuit board and the contact spring that will bypass the diode so if the light then comes on you'll know that's where the problem is.

Hope that's of help


Chris


Thanks for the info Chris!
However, I'm not sure that I totally get what you said, again, I'm very new to this. Do you have a picture to show which parts you are mentioning?
Oka aka W. Kapriandi
Märklin Z scale (mini-club) purist but not a modeler!
Offline wildstix  
#5 Posted : 07 July 2021 18:28:35(UTC)
wildstix

Indonesia   
Joined: 12/05/2021(UTC)
Posts: 146
Location: Jakarta Raya, Jakarta
Originally Posted by: Zme Go to Quoted Post
Hi. Hope all is well

You could try swapping the lights. Does it work in the other location?

If the light still doesn’t work, sometimes the tines coming from the circuit board get bent and are not making correct contact. Just carefully bend them to ensure contact is made with the light.

Best wishes

Dwight


I did and it still doesn't work. Only one side is on, either going forward or reverse. I appreciate the suggestion, Dwight, but I'm totally a stranger still to everything inside this mini machine. Care to share a picture so I can see what part you're talking about? 😊
Oka aka W. Kapriandi
Märklin Z scale (mini-club) purist but not a modeler!
Offline Poor Skeleton  
#6 Posted : 07 July 2021 22:25:43(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 550
Location: England, Cambridge
Originally Posted by: wildstix Go to Quoted Post


Thanks for the info Chris!
However, I'm not sure that I totally get what you said, again, I'm very new to this. Do you have a picture to show which parts you are mentioning?


Hopefully this picture will explain what I mean!

IMG_3212.JPG

All the best


Chris
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Offline Zme  
#7 Posted : 08 July 2021 05:40:01(UTC)
Zme

United States   
Joined: 02/10/2013(UTC)
Posts: 760
Location: West Texas
Hello. Thanks I did not know this.

Are those the two screws on the circuit board which need to be loosened at bit also? (For smooth and quiet operation)

Thanks

Dwight
Offline Poor Skeleton  
#8 Posted : 08 July 2021 08:32:53(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 550
Location: England, Cambridge
Originally Posted by: Zme Go to Quoted Post
Hello. Thanks I did not know this.

Are those the two screws on the circuit board which need to be loosened at bit also? (For smooth and quiet operation)

Thanks

Dwight


In more modern versions where the upper part of the frame is plastic, yes. I’ve not found it makes much difference on the all- metal 8874s, though.

The screw on the underside of the bogies/trucks can definitely benefit running by being slackened off a bit.

Cheers


Chris
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Offline wildstix  
#9 Posted : 10 July 2021 09:07:12(UTC)
wildstix

Indonesia   
Joined: 12/05/2021(UTC)
Posts: 146
Location: Jakarta Raya, Jakarta
Originally Posted by: Poor Skeleton Go to Quoted Post
Originally Posted by: wildstix Go to Quoted Post


Thanks for the info Chris!
However, I'm not sure that I totally get what you said, again, I'm very new to this. Do you have a picture to show which parts you are mentioning?


Hopefully this picture will explain what I mean!

IMG_3212.JPG

All the best


Chris


Man, this is awesome! Thanks so much, Chris!
I also had a discussion with Frank Daniels (zscalehobo) about this issue and he guessed that there's something wrong with my 8875's circuit board. As for to short those two points, I'm not sure if I have the skill to do that. 😥
Oka aka W. Kapriandi
Märklin Z scale (mini-club) purist but not a modeler!
Offline Poor Skeleton  
#10 Posted : 10 July 2021 22:51:33(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 550
Location: England, Cambridge
Originally Posted by: wildstix Go to Quoted Post

Man, this is awesome! Thanks so much, Chris!
I also had a discussion with Frank Daniels (zscalehobo) about this issue and he guessed that there's something wrong with my 8875's circuit board. As for to short those two points, I'm not sure if I have the skill to do that. 😥


I'd just hold a piece of kitchen foil over the two points to temporarily connect them together to prove the point. Once you've done that you can work yourself up to replacing the diode which isn't a difficult job but will involve removing the circuit board.

Good luck!


Chris
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Offline wildstix  
#11 Posted : 28 July 2021 09:23:54(UTC)
wildstix

Indonesia   
Joined: 12/05/2021(UTC)
Posts: 146
Location: Jakarta Raya, Jakarta
Hi again folks,

First of all, shoutout to Chris, who gave me a great idea for solving this issue, however, I will keep this as my last resort 😊
So I had more discussions with some users on this 8875 lighting issue.

The light bulb, on the side where it's not working, is always warm after use. That indicated some way or somehow the current is still flowing.
So one suggestion that came from those discussions, to try to change the diodes for the lights. That sounds worth trying. The thing is, I'm not that lucky of finding the diodes for 8875 lightings, so does anyone here has any info on where I can get them?

Thank you in advance, awesome users!!! 🙏
Oka aka W. Kapriandi
Märklin Z scale (mini-club) purist but not a modeler!
Offline Poor Skeleton  
#12 Posted : 28 July 2021 13:44:15(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 550
Location: England, Cambridge
Originally Posted by: wildstix Go to Quoted Post


The light bulb, on the side where it's not working, is always warm after use. That indicated some way or somehow the current is still flowing.
So one suggestion that came from those discussions, to try to change the diodes for the lights. That sounds worth trying. The thing is, I'm not that lucky of finding the diodes for 8875 lightings, so does anyone here has any info on where I can get them?


In my experience the diodes usually fail short circuit, which is to say the light is on in both directions, but it looks like yours has failed in a different way. These diodes are really hard to get hold of these days, being very obsolete technology, but a modern silicon diode will do the job, albeit requiring a bit of soldering. Alternatively, I have some spares from when I replaced the bulbs with LED modules in my 8874s and I’d be very happy to post a couple to you. Drop me a message with your address if you’d like me to do this.

All the best.


Chris
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Offline Poor Skeleton  
#13 Posted : 28 July 2021 15:06:45(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 550
Location: England, Cambridge
You may also find this video (from 6’08”) helpful which talks a bit about the diodes and how to bypass them if you’re fitting a two-colour LED module.

https://m.youtube.com/watch?v=sslYIvf3yow

Hope this is helpful.


Chris
thanks 2 users liked this useful post by Poor Skeleton
Offline wildstix  
#14 Posted : 29 July 2021 15:29:21(UTC)
wildstix

Indonesia   
Joined: 12/05/2021(UTC)
Posts: 146
Location: Jakarta Raya, Jakarta
Originally Posted by: Poor Skeleton Go to Quoted Post
You may also find this video (from 6’08”) helpful which talks a bit about the diodes and how to bypass them if you’re fitting a two-colour LED module.

https://m.youtube.com/watch?v=sslYIvf3yow

Hope this is helpful.


Chris


This is VERY helpful! Thank you again, Chris! Also thank you for your offer, but after discussing with Stephen from CK LED, I think I will go for changing the lights with LEDs.
Oka aka W. Kapriandi
Märklin Z scale (mini-club) purist but not a modeler!
Offline Poor Skeleton  
#15 Posted : 29 July 2021 16:55:02(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 550
Location: England, Cambridge
Originally Posted by: wildstix Go to Quoted Post
...after discussing with Stephen from CK LED, I think I will go for changing the lights with LEDs.


That is exactly what I did with my 8874s, however, there is a small detail you should be aware of. The orientation of the light insert is different in 8874/5 than most other diesel/electric locomotives in that it vertical rather than horizontal. This means the LEDS are shining upwards so the illumination into the lights is poor. Things are even worse if you go for the red/white module as one of the LEDs is on the other side of the module and won't show through.

I mentioned this to Stephen a while ago and he may now have a module especially for this locomotive, but it is something you should be aware of as you may end up disappointed and frustrated. For my locos I refitted the LEDs to be on the same side of the PCB and shining in the right direction, but I work in electronics and am used to tiny modern components!


Sorry to be throwing more problems at you, but I'd hate for you to be disappointed when the parts finally arrive with you.

All the best


Chris


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