I sold an electronic keyboard (I'm a USA Seller) to someone in the UK a while back. I emailed the gentleman, told him when to expect it yet he Emailed me sometimes 3 times a day with "WHEN DO YOU THINK IT WILL GET HERE???" First, I'm not the post office and I don't know how long it will take to "get there" vs, what I was told WHEN SHIPPED. So, we had one of those "OH I CAN'T WAIT TILL IT GETS HERE!" type. Here's the kicker. USA voltage and UK voltage (as well as many other countries besides the UK)  are not the same! I know the unit was working when I sold it, but it's my belief when it got to the person that won it, it was one of those "HOT DAMN OH GOODY IT'S HERE, plugged it in with the adapter I sent and BAM! fried it. So what does this person do? Files with Paypal for a refund. That freezes me from using Paypal, both buying and selling. Paypal found it in my favor but there's several precautions you can take before you ship.

1. If the Electronic item you're shipping has a pilot light or display, PLUG IT IN AND TURN IT ON THEN take your picture. This proves that the unit IS working before you ship it. If the buyer see's that then the "oops" is on their part if they get it and don't check their credentials and voltage differences.

2. If you shipping worldwide, by all means point out that any adapters you're including work on USA Voltage (which is 60 hz. or "60 cycles per second) and WARN your buyers that may be from a foreign country that their voltages may be different, and to check that USA items will work in their country. For example, if a 9V or 12V adapter is included, tell the potential buyers "Item works on 60 hz. current and the voltage rating it works on FOR THE USA!" Then if it's their fault that they haven't checked to see if USA items WILL work in their country, the egg is on their face. Always tell them what YOUR operating voltage is for the unit, and they will know what they have to do. This also applies if for example someone in  Japan is selling to someone in the to Peru or anywhere that isn't the same country as the one you use  the item you're selling in.

This is only a brief overview, use your own ideas along with these, and your electronic worldwide Ebay selling items will have a bit of a better overview and you're not left with some nimrod whining because of anxiousness or non-forethought.

Hope this helps!

Robert