Could use a hand - Picking replacement output devices for Yamaha M-45
There was a mishap with a slipped meter probe and a bright blue flash, more about that in a minute...
I'm assuming that the output transistors are toasted; they are 2SC3182 and 2SA1265. A search on Mouser lead me to this pair of Fairchilds:
http://www.fairchildsemi.com/ds/2S/2SC5242.pdf
http://www.fairchildsemi.com/ds/FJ/FJA4213.pdf
...which look like viable replacements. Are they good substitutes? Also, should I get the "O" or "R" version? (The hFE ratings are different between the two.) This amp is one of Yamaha's class AB/A where a switch on the faceplate biases the output devices into class A up to 10W, according to the literature. I don't know enough about circuit design to know if the Fairchilds will work in that situation. The schematic will be posted this evening, if need be.
So about the slipped probe, I shorted the "upstream" end of the emitter resistor to a jumper that ties into the corresponding transistor's collector. Most likely the drivers are toasted, too? I have yet to disassemble the amp and do any testing. The main 10 amp fuse blew right away. No semiconductors have burn marks - the board has a black mark; the resistor's lead and the jumper both have divots from the short.
There was a mishap with a slipped meter probe and a bright blue flash, more about that in a minute...
I'm assuming that the output transistors are toasted; they are 2SC3182 and 2SA1265. A search on Mouser lead me to this pair of Fairchilds:
http://www.fairchildsemi.com/ds/2S/2SC5242.pdf
http://www.fairchildsemi.com/ds/FJ/FJA4213.pdf
...which look like viable replacements. Are they good substitutes? Also, should I get the "O" or "R" version? (The hFE ratings are different between the two.) This amp is one of Yamaha's class AB/A where a switch on the faceplate biases the output devices into class A up to 10W, according to the literature. I don't know enough about circuit design to know if the Fairchilds will work in that situation. The schematic will be posted this evening, if need be.
So about the slipped probe, I shorted the "upstream" end of the emitter resistor to a jumper that ties into the corresponding transistor's collector. Most likely the drivers are toasted, too? I have yet to disassemble the amp and do any testing. The main 10 amp fuse blew right away. No semiconductors have burn marks - the board has a black mark; the resistor's lead and the jumper both have divots from the short.
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