Ever heard of a B1243?

[Paulr1]

Hi All,

I am trying to find details od a small 3 pin in line transistor that needs replacing in my Pioneer amp. The only markings are B1243 & AD underneath it. When I search for "B1243 & Transistor" on google I get 2 useless links.

Anyone know who uses / used to use B as a prefix or anything about this transistor. It came out of a switchmode power supply for a car amp & was blown along with one side of the mosfet switches.

Any advice would be helpful as I have no idea what I can replace it with at the moment.

Cheers

Paul

[jdoorn]

Do you mean this one :
http://www.rohm.com/products/databoo...df/2sb1184.pdf

Regards, Jan

[Hoffmeyer]

Hi Paul.

Try 2SB1243 !
It's a Rohm transistor: 2SB1243

[Paulr]

Thanks for that guys - thought I was in trouble there.

Any advice on parameters for a replacement? I know its overkill, but I was looking at a MJE15035 as I have some spare & it has similar specs

Breakdown voltages are easily covered by the 15035 as is the current capacity
VCE(SAT) is the same at 0.5V typical
fT is lower at 30MHz, but in a switchmode power supply will be operated at a lot lower
Cut off currents are higher though on both ICBO & IEBO on the 15035, being 10uA compared to 1uA

As it's in a power supply I wanted to check before using

Thanks

Paul

[markp]

For most Japanese transistors: if it starts with an 'A' it is a 2SAxxxx, 'B' is 2SBxxxx, 'C' is 2SCxxxx, and 'D' id 2SDxxxx. 2SA and 2SB are PNP and 2SC and 2SD are NPN.