This might be a better fit for the DCC forum (so I moved it there), but if the markings on the cap (capacitor?) are still visible, it should tell you what specs are required. The text markings all correlate. https://www.electronics-notes.com/a...nents/capacitors/capacitor-codes-markings.php If you are willing to do some microsoldering, you can theoretically replace the component, which probably retails for under a dollar. Just beware, the polarity of the component is marked on the body and if reversed will lead to its failure.
According to the product page, there's 2 sets of wires to the board: https://www.digitrax.com/products/sound-decoders/sdxn146k1e/#lightbox[product]/0/ The spec sheet: https://www.digitrax.com/media/apps...dxn146k1e/documents/Spec_Sheet_SDXN146K1E.pdf Have you considered the warranty and repair section from Digitrax? "Digitrax gives a one year "No Worries" Warranty against manufacturing defects and accidental customer damage on all Digitrax command stations, boosters, throttles, decoders, power supplies and layout control devices. That's it! A simple, straightforward warranty with no tricky language!" https://www.digitrax.com/support/returns/
two wire that are on the speaker and two that are on the cap. as far as warranty. there is none it is over a year.
The capacitor is a 100uF capacitor and is a keep-alive. Are you 100% certain the capacitor is dead? You can order a replacement via DigiKey/Mouser/etc, I'd suggest something along the lines of 35V or 50V as the voltage rating.
Unless you are really into small electronics repair, I'd suggest sending the board back to Digitrax for repair or replacement. Even though it's out of warranty, your cost for a new or repaired board is going to be $17 plus your shipping cost to them. Also of note, when shipping the decoder back to Digitrax by the USPS, be sure to request proof of delivery so you know when your package arrived at Digitrax. You really can't beat Digitrax "No Worries" repair even on decoders that are out of warrenty, I've used them several times when I let the magic smoke out of a Digitrax decoder.
Replacing that specific cap should not be too difficult....it's installed on 2 wires. It's not like desolder and resolder on the board itself And since you are doing that, you may want to consider using surface mounted capacitors in parallel to have a larger capacitance