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Replacing or Repairing Marker Lights and Headlights on 141 Class

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DiveController
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Hi Everyone,

I was wondering if anyone could direct me to a resource to help me with this. I have googled online and searched on the site without finding an article that will help (there may be one, I just didn't find it)

 

The lights on my 161sa began to flicker at certain points on my simple test oval. I attributed this to needing a good clean. A day or two later I have no lights on Cab 1 end with the usual single red marker operating correctly on the rear and all red and white lights, illuminating correctly when driving Cab 2.

I have taken the 'brave' step of removing Cab1 and the remaining body to expose the PCB and cabs. It appears that light is transmitted to the headlight using a fibre optic/prism from a source below the cab and I am not sure if there is a separate source for the marker lights as they can operate independently under DCC.

Could someone advise on whether they think this a a blown bulb, loose wire or something else.

There is no Irish outline model shop nearby, the nearest model shop is 35-40 miles away and I don't mind attempting the fix unless it is overly complicated.

Thanks in advance

Kevin

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Hi Kevin. Have you been trying the lights on DC or DCC? Suggest checking the switches under the loco (i.e. for DC light settings), and if DCC, try a decoder reset. Just in case it's a decoder programming issue. I inadvertently messed up a few CVs on one of my MM locos and the lights appeared to have failed, but it was just the decoder settings for lights. One of the lights had a strange flashing sequence. After a CV8=8 reset all was well again. Might be a red herring, but just in case it's not a wiring, pcb nor lamp fault. Noel

 

PS: After CV8=8 reset bare in mind the locos address reverts back to the factory default of 3 just in case you think the loco is dead because it no longer responds to its former address.

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Hi Noel,

Sorry, should have said the loco was running on DC only although this is a good chance to chip her now she's open if I can resolve the white lights issue. I think some of the decoders like Lenz Silver 21+ have the ability to set to the lights to several different preset sequences, on , off, flashing in or out of phase with other lights. Can't remember the CVs off the top of my head. Hope it;s not the PCB!

Edited by DiveController
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The 141's use leds and these usually don't flicker before blowing they usually die suddenly! I have a feeling it might be a dodgy PCB which I believe was an issue with a few of these locos. I've never stripped one of these locos down completely but I assume there are 2 leds at each end of the loco. According to the service sheet there's an led board that sits into each end so I imagine the leds are wired onto this.

 

It may simply be a loose wire so check that out first.

 

To check the led would require it being removed from the loco or you may be able to apply power to the ends of the wire feeding the led but be careful to use the correct voltage.

 

If it's the PBD that's at fault then the printed circuit powering the cab 1 lights may have burned out. It's possible to insert a jumper wire once you can identify the circuit but it would require some delicate soldering work.

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Posting a few photos to show what's under the cab which is pretty straightforward

The photo are for newbies and if you've decoded a fleet of locos and have an engineering degree in model locomotive design please don't waste you time reading on…..

image1.jpeg

Body removed from chassis (in two parts) and slotted vertically back into each other

On the chassis from left to right (Cab 1 on left towards Cab 2 'at back')

Instrumentation panel and driver's seat, cab back wall abutting the printed circuit board (PCB), blank 21 pin decoder sitting atop the PCB, light switches on blue plastic housing to switch on/off lights on front or rear of loco when running on DC (when running in consist, for example), ovoid housing for speaker when sound decoder is fitted on top of some wiring to Cab 2

NOTE ON Manual LIGHT switching:

Switch 1 turns on or/off all lights on 'Cab 2' and switch '2' operates the lights on 'cab 1', (which seems counter-intuitive). If turned off, the headlight and marker lights on the appropriate end are turned off when traveling in that direction and the red marker light on that end does not illuminate when the traveling on the opposite direction.

image3.jpeg

Removing the cab detail (engineer's instrumentation, seating etc.) is simple and involves removing two screws on top of the right and left sides (behind the white wire and to the right of the red)

image4.jpeg

This exposes a double prism which is slotted into place and reflects light from the LED upwards and then forwards as the headlight (the LED is located at a lower level than the headlight itself, as the engineers cab is directly behind the headlight)

image9.jpeg

The observant reader will have observed that the white wire is disconnected in this case and is the source of the problem here. I was not certain that the MM141s had LEDs (which they do) as opposed to bulbs and hence the likelihood of an LED failing is far less than that of an incandescent (Thanks, IT)

I guess the purchase of a small wire stripper is now in order, not to mention a small soldering iron.

I am still not certain where the wire needs to be soldered exactly or whether I need to remove the bogie to do that …. ( I believe that the motor is incorporated into the bogie under cab 2 (rear wheel drive!, the only way to go:D)

Edited by DiveController
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Glad you found the source of the trouble!

 

The leds are mounted on a flat circuit board that fits underneath the cab, it may be stuck to the bottom of the cab detail in those photos.

If you can't see where to solder the wire you may have to remove the other cab and check the wiring on the opposite end's light board.

 

Anyway, it's a simple enough fix.

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