DCC Specialties. Jack Wabbit explosion.

[Myracan]

Hey all. I just blew up a Jack wabbit stationary decoder. Tell me I'm not crazy. I have installed 4 JWs all working as expected. Just finished programming 5th one. Proceeded to program 6th one. Long story short BOOM. Large capacitor blew up scared the #@@# outa me. After inspecting blown cap I noticed positioning of large cap was rotated 180 degrees compared to the other 5. Seems the cap that blew, the polarity is reversed to the other 5. Now I am no electronics expert but I'm just assuming this blew because polarity was reversed. This looks like an electrolytic cap so polarity matters? My question do you think other damage may have been done to the board, can i just replace the cap (correct polarity of course) or is it toast?

[John]

Contact the manufacturer, don't take the cap off the board .. let them exchange it -- free of charge -- thats a manufacturing defect if its as you describe

[Myracan]

Contact the manufacturer, don't take the cap off the board .. let them exchange it -- free of charge -- thats a manufacturing defect if its as you describe

Problem is I bought these last 2 off of an ebay seller. Not sure they would warranty it. As far as I understand Tonys Train Exchange is the seller/ manufacturer. Would they warranty it even tho I didn't purchase from him. I dunno. If the world was normal I'd just order a new one from Tonys but doing that now with transborder shipping tarriffs duties and who knows what else gets tacked on I'm not going to risk it. So if I can replace the cap thats what I will do.

[signalmaintainer]

Hey all. I just blew up a Jack wabbit stationary decoder. Tell me I'm not crazy. I have installed 4 JWs all working as expected. Just finished programming 5th one. Proceeded to program 6th one. Long story short BOOM. Large capacitor blew up scared the #@@# outa me. After inspecting blown cap I noticed positioning of large cap was rotated 180 degrees compared to the other 5. Seems the cap that blew, the polarity is reversed to the other 5. Now I am no electronics expert but I'm just assuming this blew because polarity was reversed. This looks like an electrolytic cap so polarity matters? My question do you think other damage may have been done to the board, can i just replace the cap (correct polarity of course) or is it toast?

Yes, polarity certainly matters with an electrolytic capacitor. They tend to protest quite demonstrably when the anode is hit with negative DC.

[John]

Problem is I bought these last 2 off of an ebay seller. Not sure they would warranty it. As far as I understand Tonys Train Exchange is the seller/ manufacturer. Would they warranty it even tho I didn't purchase from him. I dunno. If the world was normal I'd just order a new one from Tonys but doing that now with transborder shipping tarriffs duties and who knows what else gets tacked on I'm not going to risk it. So if I can replace the cap thats what I will do.

Doesn't hurt to ask Tony's   .. explain the problem . worst case, you end up buying a new one .. or you fix yourself . .

[tehachapifan]

Insert obligatory "earth shattering kaboom" reference here. I mean, c'mon, the decoder is called a Jack Wabbit???

[peteski]

Yes, Aluminum electrolytic caps (and Tantalum) caps are polarity sensitive.  Both will experience spectacular failure if installed backwards.

The liquid electrolyte in Aluminum will heat up to the point of boiling. That builds the pressure inside the metal can to the point it blows open. The top of a cap has some grooves stamped in it to weaken the metal so it can crack open under pressure.  It kind of blows its top off!

Tantalum caps fail in even more spectacular way.  The tantalum (which is a type of metal) plug inside them heats up to the point in starts glown red. The cap can catch on fire.

Yes, this type of failure should be covered by the manufacturer.

[Myracan]

Thanks for responses guys. Heres another thot. After studying this thing a bit that large capacitor would only be used to throw solenoid type switch machines would it not? Seeing as I am only using tortoises that cap is not even needed perhaps. Would this thing work if I removed that blown cap, provided no other damage has been done to it? A bit of a jump down the rabbit hole but I gotsta know. If you don't here from me again then I blew myself up lol.

[signalmaintainer]

Thanks for responses guys. Heres another thot. After studying this thing a bit that large capacitor would only be used to throw solenoid type switch machines would it not? Seeing as I am only using tortoises that cap is not even needed perhaps. Would this thing work if I removed that blown cap, provided no other damage has been done to it? A bit of a jump down the rabbit hole but I gotsta know. If you don't here from me again then I blew myself up lol.

I'd just replace cap. Easy-peasy.

[Myracan]

I'd just replace cap. Easy-peasy.

Thats the plan. Order from Ali Express yesterday. It was difficult finding one that matched the blown one. 25v 8200uf. I will post if successful or not. Cheers.

[garethashenden]

Contact the manufacturer, don't take the cap off the board .. let them exchange it -- free of charge -- thats a manufacturing defect if its as you describe

I still think this is the correct thing to do. Additionally if I were the manufacturer I’d want to know about a fault like this so that it can be addressed with the supplier.

[signalmaintainer]

I still think this is the correct thing to do. Additionally if I were the manufacturer I’d want to know about a fault like this so that it can be addressed with the supplier.

It was not a component fault, but an installation ***** up, as the OP noted in the first post.

Replacing the cap is straightforward and less troublesome.

[peteski]

It was not a component fault, but an installation ***** up, as the OP noted in the first post.

Replacing the cap is straightforward and less troublesome.

Bad or improperly installed component - either way it is still a manufacturing defect.

[Myracan]

It was not a component fault, but an installation ***** up, as the OP noted in the first post.

Replacing the cap is straightforward and less troublesome.

Received new cap and replaced. Easy peasy. Programmed all 4 decoders. All work great. So no other damage. Also still have all my fingers.