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Hi elwabb,

pls post a picture of that specific transistor. The abbreviation ...C4370A is commonly used by japanese transistors and the not shown postfix is usually a 2S... - completing the part number to 2SC4370A. Nevertheless to make sure a picture might tell us/me the manufacturer of the device by identifying the logo (if there's any one at the device). This could be any other "strange" looking letter or some sort of a lasered logo specific for that manufacturer.
You might find something similar to that shown here:

In case it comes out as the mentioned KTA4370A you're in luck and you already got the right datasheet.
According to my quick investigation there's also a divice known as 2SC4370A, but I couldn't find any datasheet to download. Nevertheless the manufacturer supposed to be NEC and the device comes in a TO-251 package.
I finally found at least something:

It supposed to be an NPN audio driver/output device with Vce=160V, Ic=1.5, Ptot=20W, hfe=70-240 and an ft=100MHz(!) and comes in a TO220 case.
Hm, not bad that buddy, in particular the ft of 100MHz would be a good reason to consider that transistor in the next design ;)

According to the PDF-files a recommended replacement would be the 2SC4159 (Sanyo), 2SC3298 (Toshiba), 2SD1587 (NEC), 2SD1772 (Matsushita) and finally the 2SD1763A (Rohm).

Hopefully that was of any considerably help ...
hi elwabb,

I compared both datasheets with the result that they're both almost identical except for the Vce rating. The NEC type has a 20 volt lower Vce than the KEC one. If the voltage in your equipment (whatever it is) comes close to or exceeds a Vce of 160V you better be sure who's the manufacturer of it in case you really wanna replace it. Besides I haven't checked the voltages of the recommended raplacements for the NEC 2SC4370A. You might do a little further investigation yourself ;)

thanks alot,I don't have a high resolution camara to take pictures of it but I'll try to describe it to you/you all To-220 type it has a K up top cenert the under it it has C4370A then under that has a Y then a space then a 044.Thanks I really appriciate your help.
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