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I have an Adcom GFA 7605 and one of the channels blew. Now there's about 60 volts on that channel's speaker terminals. I took the board out. It looks like transistors Q8 and Q16 need replacing. I don't know how to identify them. Q16 is in a TO-92 has what looks like house numbers on it. KSP

42

-209 I would have to remove Q8 to see its face. It has four pins. I did a little troubleshooting with a voltmeter by probing different spots on the bad board and comparing to the readings I took at the same points on a working channel's board. The region of the board with the inappropriate high voltage readings contains those two transistors. Q16 is not cracked but looks a bit singed and I can't tell about Q8 but one of its pins has the wrong voltage. Of course a bunch of other solder points on the board have wrong voltages too, but one or both of those transistors look to me most like the culprits. I could try contacting Adcom but it seems unlikely they would help me. How should I fix this amp?

Reply to
kellrobinson
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I have found Adcom to be very helpful when I have contacted them.

Leonard

Reply to
Leonard Caillouet

There is a listing in the NTE XRef that crosses the KSP42 to a NTE287, which is a 300V NPN in a TO-92 case. The -209 might be a beta grouping for that part, or some other special selection criteria.

--
Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in 
the address)

Never take a laxative and a sleeping pill at the same time!!
Reply to
DaveM

Helpful, thanks.

Reply to
kellrobinson

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