New amplifier problems

[radu8982]

Hi. I recently started a project to build a stereo hi fi amplifier, but I came across some problems.One amplifier module burned and the other sounds weak about 25W at +-40V.I did not used all the original transistors 2sa872(2n5401) , MJE5731A TIP50(MJE15030-MJE15031) ,MJ15025 MJ15024(2SA1943 2Sc5200).
I want to fix the working module ,the schematic i used is the one below.

[jaycee]

You cannot simply substitute transistors in this way. The circuit will be oscillating and the compensation will have to be re-designed to cope - assuming your substituted parts are suitable for the circuit.

Your big problem is that MJE15030/1 drivers and 2SA1943/2SC5200 outputs are a LOT faster than the original devices. The drivers are also used in a Sziklai configuration with the BF422/423 predrivers - this is also prone to oscillation unless correctly compensated.

[radu8982]

I would have used the original transistors but i can not find them in my country.I want to know how the schematic should look like with the transistors i am using.I also want to replace the BF423/BF422(below is a picture of how i got BF423) with 2N5401/2N5551 if it s posible and probaly 2sa1943/2sc5200 with 2STA2121/2STC5949.If the transistors are not appropriate please help me find some wich are.

[rrrremus]

Radu, you cannot expect people to be of any help when you did not use the parts that the designer recommended.
I also live in Romania at this time and i never buy electronic components from this country because most are fake. You can buy with confidence from Farnell or from Mouser.

[radu8982]

With some help i got a working module and i want to now how to make it safe so i won't encounter problems.