Need advice with Adcom amp repair. Question about matching transistors.

[JW]

Hey folks,

I had a mishap drilling into my Adcom 535 amp and destroyed a transistor on one side. It is a 2SA608K transistor. I attached this part of the schematic (Q611 top right hand corner.) I have some replacements on hand. I'm just not sure if these transistors need to be matched for both L&R channels.  I only included the left channel schematic, but obviously the right channel is identical.

Please let me know if they need to be matched.

Thanks guys!

 

[JohnRoberts]

Hey folks,

I had a mishap drilling into my Adcom 535 amp and destroyed a transistor on one side. It is a 2SA608K transistor. I attached this part of the schematic (Q611 top right hand corner.) I have some replacements on hand. I'm just not sure if these transistors need to be matched for both L&R channels.  I only included the left channel schematic, but obviously the right channel is identical.

Please let me know if they need to be matched.

Thanks guys!

Q611 does not look like matching would be useful.

You may want to look for other related parts that were damaged by the failure.

JR

 

[Audio1Man]

Hi JW
John is correct. Q611 is a current limiter. Almost any PNP will work. This stage is part of a protection that will keep the input circuity from failure if the output stage fails.
Duke

 

[JW]

Very cool.

Thanks so much guys. I did damage  a couple resistors too with the drill, but I sourced those, and haven't powered it up at all. So, should be good to go once I replace that transistor.

Thanks!