Coding of Japanese transistors

Do you also have lots of Japanese transistors in your junkbox with hard-to-understand coding ?

Those codes might not be so difficult to understand. You might be richer than you think and this article can help you finding a useful application for those forgotten semi conductors.

Most Japanese transistors have been coded according to the JIS, which stands for “Japanese Industrial Standard”. The JIS looks as follows:  Number – 2 characters – Serial number – Suffix

The number is one less than the total amount of contactwires. (A standard transistor with base, collector and emitter has a 2 as a start for the coding. Examples; 2SA1187, 2SB646, 2SC733)

The two characters refer to the application as follows:

SA: PNP HF transistor
SB: PNP AF transistor
SC: NPN HF transistor
SD: NPN AF transistor
SE: Diodes
SF: Thyristors
SG: Gunn devices
SH: UJT
SJ: P-channel FET/MOSFET
SK: N-channel FET/MOSFET
SM: Triac
SQ: LED
SR: Rectifier
SS: Signal diodes
ST: Avalanche diodes
SV: Varicaps
SZ: Zener diodes

The serial number is in the range 10 till 9999. The optional suffix indicates that the semi conductor has been approved by various Japanese authorities.

Note: Since most common transistors have a code starting with 2S, this part is often omitted;  A 2SC733 can be found as C733.

Also be aware that the internet is your best friend in order to find out with what type of transistor you are dealing with. For example I found some transistors with code C1921. I searched for 2SC1921 and found

http://www.paulswan.me/arcade/datasheets/2SC1921.pdf

Here I discovered I owned some transistors from Hitachi designed for hi voltage video circuit applications.