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basic*illusions 25th February 2005 11:43 PM

Questions About Pioneer VSX-* Transistors
The subject is a Pionner VSX-D557 5.1 DD Surround Receiver. It was purchased recently in non-working condition for next-to-nothing. My hope was (and still is) that I can repair it and put it in my kids' play room. The receiver is in excellent physical condition and shows no sign of misuse externally. The issue with it is no power from the front right speaker output - though all four of the other outputs are fine (it apparently has discrete amplifiers), and the sub out does send an appropriate signal.

After pulling the shroud and inspecting the inside of the machine, I quickly discovered that the right channel suffers from two fried transistors (2SA1962, and 2SC5242.) Only the collector on the 2SA1962 remains intact; the other five stems being melted completely away from their respective contacts. There are also clear signs of arking from the emitter on the part of the 2SC5242.

Now to the questions:

1.) Is this simply a blown set of transistors that I can easily switch out myself, or is this an indication of something more serious that is likely wrong with the receiver?

2.) If the potential for a repeat of the transistor failure is caused from somewhere else in the machine, is there also a realistic danger of potential fire - considering the signs of arking from the 2SC5242 emitter?

3.) Are the model numbers for these transistors interchangeable, i.e., will 'any' 2SA1962 and 2SC5242 transistors work - or must they be replaced with the Toshiba models currently in the machine?

I hate to ask so many questions in my first post here, and for this I apologize. I have extensive experience with cleaning and maintaining vintage audio, but this is my first forray into actual repair (beyond simple issues like light and switch replacement/restructuring.) I'm sure I can switch these out in about 15 or 20 minutes - but I'd like to think that I am not going to burn my house down if I do.

Any information/advice would be greatly appreciated.


anatech 25th February 2005 11:53 PM

Hi Michael,
Any of those number will work as long as they aren't fakes. Toshiba is the only one that makes that number as is Japanese custom (unlike US Jan).
There are more blown parts for sure. That is the normal way they blow.
Once you get it running it should be okay as long as you don't crank it. Make sure the fan works properly.

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