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Re: Duplamat 300w transformer replacement

> From: "David Ozenne" <dozenne at 10fold_com>
> I have no experience with the Dupla unit in particular, but
> before you spend a lot of money on a new one, see if you just
> blew the fuse.  A lot of consumer transformers come in sealed
> plastic boxes with a fuse inside.  (As a tinkerer, this strikes
> me as stupid or even perhaps dishonest.)  When you accidentally
> short them or otherwise draw excessive current, the fuse blows.
> Not knowing any better, you just replace the whole thing.
> I've got a couple of transformers that "died", and I just cut
> the plastic open, took out the old fuse, and soldered in a fuse
> holder.  Better than new!
> P.S. If you get a new one anyway, send me your old one.  I'd
> gladly pay shipping!

I don't think you'd want this one. Dupla did a fine job of epoxy filling the
entire plastic case to turn it into a 13 lb 4" cube. They were at least kind
enough to put an external fuse in it. The fuse checks fine. There is no
continuity on the primary side. The secondary has continuity on the banana
jacks. Needless to say, it stays cold and has no output voltage.

Considering the construction of the unit, I think I am far better off making
one that is easily repairable. I've tracked down all the parts thanks to
some help from APD members. Basically, I'm going to copy the Dupla layout
with panel mount banana jacks and fuse holder, but put it in a vented
aluminum case that I can mount in a nice dry area under the tank within the
stands framework.

I bought the Dupla unit the first time out of basic fear of water and
electricity. Even with everything in a GFCI outlet, and a titanium ground in
the water, I am still paranoid, but it hadn't crossed my mind that
transformers are a consumable as well. When I get done, I'll probably write
something up and put it on my web site (The Dummies guide to 12A 24V
transformers;). It looks like I can build the unit for $102 + shipping, but
next time, all I'll need is a $45 transformer. The numbers look much better
than the $271 I paid for the Dupla 3 years ago.

All in all, I feel fortunate that it wasn't the heating cables that died,
that would have been serious:)

Jon Wilson