I have a couple blown Alpha 230 amps here to rebuilt. Both are blown. The service manual talks about how the design takes advantage of the high frequency of the original outputs. 80MHz for NPN and 60 for PNP. The best replacements I can find have an fT of 30 (2SC5200 and compliment). Will that cause issues? And does anyone know of better parts that are available?
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Hi, I write through a translator, I hope you will understand me, I also have such an amplifier to repair, that's why I found your post. I suspect you have solved your problem by now because it's been almost a year. I think that the transistors you mention can be used are or were commonly used in power amplifiers. Remember that the project was created in the late 70's of the last century and the Japanese put in what was the best at that time. I have repaired many amplifiers, but this one causes me a lot of trouble, due to the use of current mirrors, it resembles a high-power operational amplifier. I fixed it, however, under full load, the final stage is damaged. I'm thinking about reworking the final stage as in alpha 400 because I think it caused a lot of problems for the creators themselves.