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Discussion Boards => General Discussion => Topic started by: Osprey797 on May 23, 2016, 06:12:16 PM

Title: RFI filter capacitors
Post by: Osprey797 on May 23, 2016, 06:12:16 PM
When installing a Digitrax decoder (in this case a DN125) the instructions say to remove the filter capacitor where installed.

I have a Bachmann N Scale N&W J Class 611 with the PCB in the tender, which ran fine in DC analog mode on my Digitrax DCC system. I installed the Digitrax decoder onto the PCB and desoldered two capacitors C1 and C2. The decoder programmed okay, but the engine will not run. I assume that one of the capacitors has to remain, but I don't know which one.

Has anyone successfully installed a wired decoder to the J Class 611 tender? Which capacitor should be removed, if any?
Title: Re: RFI filter capacitors
Post by: Hunt on May 23, 2016, 06:37:29 PM
C3 and C1 capacitors were the ones to remove.
Title: Re: RFI filter capacitors
Post by: Osprey797 on May 24, 2016, 12:42:02 PM
Correction: I desoldered C1 and C3 capacitors. I don't think the decoder is bad because it responded to JMRI programming.
Title: Re: RFI filter capacitors
Post by: brokenrail on May 28, 2016, 10:20:28 AM
Ya take them off they are trouble waiting to happen .They will short out and blow your decoder.They were used in automotive applications and the type used are just junk.They were elimated after 1 production year and cost the manufacturer and the technitions nothing but a head ache.
Johnny
Title: Re: RFI filter capacitors
Post by: Hunt on May 29, 2016, 02:22:07 PM
Quote from: brokenrail on May 28, 2016, 10:20:28 AM

Ya take them off they are trouble waiting to happen .. . .


Not all DCC decoders are adversely effected by the capacitor(s) across the motor circuit.


Quote from: brokenrail on May 28, 2016, 10:20:28 AM

. . ..They will short out and blow your decoder.. .  .


Highly unlikely in a model locomotive context.

Quote from: brokenrail on May 28, 2016, 10:20:28 AM

. . . They were used in automotive applications and the type used are just junk.They were elimated after 1 production year and cost the manufacturer and the technitions nothing but a head ache.
Johnny


Not applicable in a model railroad context