I am repairing a 481 for a friend (and customer). The original speaker is shot. I ordered a universal speaker and capacitor kit from Doug Peck at Port Line Hobby Supplies ($10). I installed it (with negative end of cap toward speaker as was the original Gilbert) and it works fine, but I was wondering - - should the new capacitor be non-polar (or bi-polar)? The one that came with the kit is not. It works OK, but my understanding is that polarized caps like this one can be dangerous (i.e. unexpectedly explode) when used with AC. Thanks in advance for your help and expertise with this question.

You are not putting a constant DC accross the cap in the wrong polarity so it will be ok.

Tom Barker's book says "use a 25uf at 35 volts. Polarity not important"

Carl

Thanks Carl. If you and Tom B are good with it, so am I. The universal kit comes with a Mouser 8ohm 0.1W speaker of larger face diameter and smaller back-end diameter than the original speaker and a 25uf Sprague capacitor. Barker cites using a 3.2 ohm speaker, but the instructions with the universal kit mention that 3 ohm speakers are no longer available. So far so good. It seems to work OK.

quote:

Originally posted by Sgaugian:
...The universal kit comes with a Mouser 8ohm 0.1W speaker...It seems to work OK.

I'm surprised you can get the volume out of that speaker.

The diesel roar is maybe not quite as loud as before, but the horn is as loud or louder than ever.