I've noticed Boomboxes offered for sale which are from the Japanese market (mostly late 1970s-early 80s). Many do not use the stadard AC plug and have different transformers....100 volt vs. 110 volt.

what do I need to know about these...I don't want to fry internal components.

What I know...

The AC plug is standard, just not polarized like modern U.S. plugs. Japanese domestic plugs work in U.S. outlets.

Voltage (if it isn't switchable, which it usually isn't) is 100v, 50 or 60 Hz (because Japan uses different frequency current in different parts of the country).

U.S. 117-120v. current may fry a piece of Japanese electronics and it may not, depending on the tolerance of the transformer and the actual current in your area. Much of the U.S., I hear, is on the low side. Chances are, if you get fried, it will be over time and not right away. I've had a Victor (Japanese domestic JVC) VCR plugged directly into my U.S. house current for ten years with no problems whatsoever.

However, just to be on the safe side, I use small 117-100v. step-down transformers on most of my Japanese-domestic electronics. Step-downs can be had on the Internet, and they're plentiful at every major electronics store in Tokyo (Laox, Ishimaru, etc.).

One more thing. The Japanese FM band is 76-90 MHz. If you buy a unit with that FM frequency range, your listening in the rest of the world will obviously be limited. However, many radios sold in Japan receive the entire ("wide") 76-108MHz FM band so they work both inside Japan and outside of Japan for travellers and tourists.

(Sometmes you will see TV channels 1, 2, and 3 printed over the upper end of the 90-108MHz portion of the FM band, because those three Japanese TV channels transmit in the 90-108MHz range. Those numbers mean nothing outside of Japan.)

As an add on to this, I have never fried anything plugging a 100v Japan box into our current and I have several. I cant really say over a LONG period of time what may happen. If something does burn i'm not sure you would be able to pinpoint it to the voltage difference either because power supply components can fail anytime. I would say, plug er in and jam!!!