copandengr

Transistors are nothing more than a very fast switch. They are either NPN or PNP. The size of the transistor determines how much current it can flow without burning up. Any NPN Darlington type transistor rated at the same or higher current flow will work if it will fit into the space provided. Go to a good industrial electronics store and ask to see their ECG book. It will describe the electronic features of the transistors you are referring to and will quickly let you determine if the you gave numbers are interchangable. Remember to always go for more current capacity, never less.

copandengr

I have no idea why your BAC would be working as you describe it. The web page referred to in the earlier post does say that in normal operations the valve is actuated many times a second. This is what burns the transistor out in the first place. Heat is what destroys discreet components. Heat comes from too much current flow or inefficient heat sinking.

Just make sure you go for a larger transistor and make absolutely sure you install it correctly. If you put it in backwards it will stay "turned on" all the time. Most circuit boards have a silk screened outline on the area where the component mounts. When installation in a particular way is called for there will be like a circle with a flat side, or maybe the letters e,b, and c. A transistor will have a flat side on it, so install it the same way. Some transistors will have a dot on them, some will have the emitter, base and collector identified with letters. Just go the correct way.