Massoth Light Bar with external Power Cap

andyspencer

andyspencer

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30 Oct 2009
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Hi all,

Just wondering if anybody has added an external capacitor (not a Massoth power cap) to the current version of their digital light bar? The manual says it needs to have an electrical strength of at least 35v. I've just tried adding a 35v 3300uf cap to the connects as per the manual and all I get is weird flashing/strobing of the lights... Remove the capacitor and all returns to normal. Wanted to try this on the light bar before I added a cap to the 8 function mini decoder in my other coaches.
 
John S

John S

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5 Nov 2017
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Exeter, Devon, UK
Would suggest starting with much smaller value capacitor, if I read correctly, this is the new style lighting board, which is already fitted with a 22uF capacitor.

Massoth's advice on the subject for additional high capacitance capacitors is to include a resistor and a diode, which could be utilised to good use on the 8 Function Decoder.

Note...2200uF and below are in the acceptable range, that if installed correctly will not "trip" the CS into thinking it is encountering an overload, values above are likely to cause "tripping" of the CS.
 
Last edited:
andyspencer

andyspencer

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30 Oct 2009
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Thanks for the replies. I've just tried a 220uf cap and get the same result :(


I'm looking at page 7 of this manual which only mentions the voltage, but says it can be done without any additional electronics...
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
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Tamworth, Staffs.
Are you *sure* you have correct polarity, and connection points?
 
Greg Elmassian

Greg Elmassian

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8 Mar 2014
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yep, my first question too in the first response to him :)

Looks pretty simple... maybe you should take the cap, disconnect it... charge it with a battery and see if it holds a charge.

Stay under 35v! Wear eye protection! (don't ask me how I know this)

Greg
 
andyspencer

andyspencer

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The more I'm thinking about it, would it make more sense for the cap to be on the Dec+ and Dec- connections like if you were using a Massoth power cap unit? I've not seen the Elko+ connection on any other decoder before.
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
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Tamworth, Staffs.
The more I'm thinking about it, would it make more sense for the cap to be on the Dec+ and Dec- connections like if you were using a Massoth power cap unit? I've not seen the Elko+ connection on any other decoder before.
You could call or email Massoth?

I know Peter is no longer there, but I have heard good reports of support being a lot faster than in the past.
 
P

perpetualnewbie

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30 Apr 2019
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United Kingdom
Thank you! This is relevant to me as well. What about slapping a small resistor or choke on it to limit inrush current, with a diode t'other way for output?
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
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Tamworth, Staffs.
Any update Andy? - Original Poster..

One other thought...................
There are many 'effects' on the lighting options in the latest decoders.. None of these are turned on, I suppose?