Blue Mallet - rear lights brighter than front after decoder upgrade

Ralphmp

Ralphmp

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Second issue of the day from me.

I've replaced the 2 x 55021 decoders in my Blue Mallet.with a Massoth XL. All works as expected in terms of driving characteristics and sounds, but the rear lights are noticeably brighter than the front. (Loco is set to 14 speedsteps, Navigator programmed for 14 speedsteps and digital operation, so I don't think this is a "speedstep mismatch" issue.)

As part of programming the decoder I reduced the output voltage to the lights as (a) the loco uses 5v bulbs and (b) the first time I fitted a decoder I didn't do this and the 5v light bulbs shone very brightly and very briefly!!!. I set a value of 6 in CV50, CV53 and CV112 which should give around 5v output to the lights.

However, I believe the loco has a stabilization feature which provides a constant 5v when running, so I'm wondering if by reducing the input voltage to this from track power to 5v I've somehow introduced the "dim front light" symptoms. Has anyone else has seen this issue or could anyone shed some more light (sorry!) on the problem.

Thanks again!
 
Possibly your correct. However, we really need to know how you have connected the XL. Does the loco have an adapter plug socket or have you hard wired the decoder in.
 
Sorry, should have made it clear. I used the 55026 adapter plus the two sets of motor wires that came with the XL. (I followed the guidance from Whatlep in a previous GSC post - very clear).
 
LGB used 6 volts for their lights and smoke units in many engines.
When programming lights, they send short high frequency pulses at V+ to the lights, the pulse width is relevant to the number placed in the controlling CV.
I find LGB decoders usually have bright lights with a setting of 4 or 5, not 6 on my engines, but I have to remember the V+ line from my decoder is 24 volts (My DC supply is 30 volts for my DCC unit).

If you have a system with lower track voltage then the cv value for the brightness would be a higher number.
 
Phil, as you've connected your XL via the existing LGB main board, then the voltage stabiliser(s) on the board will still be in operation and doing their job - as far as I understand, you can leave the XL lighting function at full voltage and the onboard factory electronics will drop it to whetever the lights need. I certainly didn't need to adjust anything on the decoder when I put an XL into my factory-sound (serial) black DR Mallet to replace the archaic 55020+55030 setup that it originally came with.
You should only need to drop the lighting voltage CV on the XL if you were to connect the lamps directly to the XL, bypassing the factory board in the loco.

Jon.
 
My understanding is that the the front and rear light outputs always have the same dimming level. However with outputs A1 to 4 It's possible for some to have different dimming levels than others.
This suggests that you may have connected some of the lights to one or more of these outputs.

Rather than dismantle the loco I suggest you first swap one bulb from front to rear just in case it's a simple matter of the front ones being from a different batch to the rear.

If that's not the problem change CVs 53 and 112 from 6 to 198 this will set all four outputs A1 to 4 to dimming value 6.

If that doesn't change anything then I suggest double checking the wiring. If all is correct you could swap the reverse light wire to a spare output (A1 to A4) and dim it independently (starting at 6) to match the front.
 
Thanks for all the suggestions in response to my post last September. I guess we'll never know what the issue/resolution was as I've recently removed all the original boards and replaced with an XLS.

I plan to install a pulsed smoke unit and needed to remove the original gubbins plus the XL decoder I fitted to make sufficient room.

(and I'm happy to report that all lights are working at the same brightness level now)
 
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