What kind of transistors - pin info and replacements?

[rwc]

The more powered prosumer speakers I open the more I notice that every amp inside looks the same! From tannoy actives to event actives I'd almost say the same company made the amps, if they didn't have some ever so slight differences.

They use transistors I'm not used to seeing in power amps, with six legs instead of three(I guess the positive and negative side are in the same chip), and they aren't coin shaped with a hole on each side but rather just look like larger driver transistors.

Where can I find more information on these, what kind to get as replacements, etc? like which leg is which.. I can tell which leg is the collector leg easily by pegging the MM there and seeing + and - 40 to 80v, the emitter leg usually by following wires and traces but some of this stuff is so small and the wiring is always really short to other areas. Combine that with my not so well lit work area and it takes way longer than I like it to to find out where stuff is going.

I've fixed a decent amount of these speakers and it's never actually been the driver or the transistor that is bad, but another part of the speaker. But someday I know that will be the part that is bad and I'd like to learn as much now before it is.

Thanks.

[rolandk]

Transistors usually have their name printed on them (2N4401, etc.). Find it and do a google search to get the data sheet. They also usually have the name or logo of the manufacturer and a date code, so it can be a little tricky.

[The Scum]

with six legs instead of three

Sounds like a power opamp. It's an opamp front end with a modest power output stage.

How do the markings read? I've got a hunch that the part number starts with a "TDA."