Japanese-market (100V) gear from Japan - rating plates, step-down transformers, ジャンク wording, heavy-box shipping

[RenSynthJp]

A fair share of the threads on this board are about Japanese gear (SH-101, Alpha Juno, CS-30, PSR, Korg presets), and some of it, plus the amps and decks people use to listen back, comes in second-hand straight from Japan. Japanese-market units arrive with a few quirks worth knowing before they reach the bench, so here are some notes from the hi-fi side that carry over.

Read the rating plate first

- Japan runs on 100V AC, at 50Hz in the east and 60Hz in the west. A lot of domestic-market gear from the 70s-90s has no voltage selector at all: the rear plate just says AC100V.
- On 110-120V mains a 100V unit will usually run, but 10-20% over its rating means more heat and more stress on the caps. A step-down transformer (120 to 100V) rated comfortably above the unit's draw is the usual fix.
- On 220-240V mains, plugging in directly is instant damage. A step-down transformer is mandatory there, not optional.
- Mains frequency matters for anything that takes its timing from the mains, like older belt-drive decks with AC synchronous motors. Quartz-locked direct drives (the Technics SL-1200 family, for example) don't care.
- If you plan to rewire for local mains instead, check whether the power transformer has a tapped primary before buying. That is a bench question, and the listing will rarely answer it.

Japanese condition wording

- 動作確認済み - seller says it powered on and worked. 動作未確認 - untested.
- 現状品 - sold as-is, with no functional guarantee even if it powered on for the seller.
- ジャンク - junk / for parts. Often the cheapest bodies, and fine for a repair project if you price it that way.
- 傷・汚れあり - marks or staining. Japanese sellers tend to be very literal here, and it is priced in.
- ガリ - scratchy pots or switches, very common on old amps and synths, and usually a cleaning job.

Searching the exact Japanese model string turns up far more listings than the English name does.

Shipping heavy boxes

Couriers charge on the greater of actual weight and volumetric weight, which is length x width x height / 5000 (cm to kg) on the carton actually used. A 14 kg amp in a 55 x 45 x 25 cm box is 55 x 45 x 25 / 5000 = 12.4 kg volumetric, so it bills at the real 14 kg. EMS caps at 30 kg per parcel, so ship big pieces separately rather than consolidating them into one heavy box.

If you go through a proxy, compare fees per item vs per order. With OneMall (the source of the guide below) it is ¥300 per item on most marketplaces and from ¥200 per item on Yahoo Auctions, the first six orders consolidate free, and items are stored free for 90 days after arrival (30 days after consolidation). Optional unboxing photos (¥500 / ¥700) let you see the rear plate and the knobs before it ships. For US addresses the current carriers are ECMS, DHL and Japan Post EMS (DDP, declared value up to USD 2,500); the live quote for your address is what counts. Since August 29, 2025, US-bound parcels of any value go through customs and pay applicable duties, taxes and fees - the $800 de minimis exemption no longer applies - so add that before comparing with a local price.

The OneMall team wrote a longer guide to buying Japanese vintage hi-fi from Japan and the 100V question, with dated listing prices and per-country shipping quotes for a 14-15 kg amp and turntable. Disclosure: OneMall is a commercial Japan proxy-shopping service and that article is the source for parts of this post.

For those who have run a Japanese-market synth here for years: do you keep it on a step-down transformer, or did you rewire the primary?