Harman Kargon AVI=150 Thermal shot noise

JasonLee · 18th January 2007, 03:31 PM

Hi, i m a new member. I reside in Singapore. I got a AVI-150 months ago. When i turn it on, it works perfactly in the first 5 to 10 minute. But after that, it started with a loud "Poom !" from the right speaker. I knew that it's a kind of transistor failure & cause DC off-set on the right channel. Anyone could lead me to a link to get the circuit schematic? Or maybe just let me know what transitor is used on the differential circuits?

Jan Dupont · 18th January 2007, 09:01 PM

Have you checked for bad soldering ??

JasonLee · 19th January 2007, 04:04 AM

Alreay checked & resolder all suspect joints.

JasonLee · 21st January 2007, 10:08 AM

Spend the who;e sunday afternoon to replace & swap some of the 2SC3200 (Swap) 2SA1268 (Replace new) problem is still on the right channel. But when I shake thr 2SC3206 before the protection circuit come into action. The right ch noise seems stop & then comes back. Will do a AB swap use the same transistor from left ch & see if the noise goes to the left.

JasonLee · 4th February 2007, 03:48 PM

While i do a left-right swap of the 2SC3206. Accidentaly i cause some short circuit between the legs of transistors. Causing two resister burned. (R227-R & R229-R). I dicided to stop till I get all transistors & resister before I work on it again.

JasonLee · 12th February 2007, 05:11 AM

Finally I got this AVI-150 sing again. The shot noise is from the 2SC 3206 (Driver).

18th January 2007, 03:31 PM	#1
JasonLee diyAudio Member Join Date: Jan 2007	Harman Kargon AVI=150 Thermal shot noise Hi, i m a new member. I reside in Singapore. I got a AVI-150 months ago. When i turn it on, it works perfactly in the first 5 to 10 minute. But after that, it started with a loud "Poom !" from the right speaker. I knew that it's a kind of transistor failure & cause DC off-set on the right channel. Anyone could lead me to a link to get the circuit schematic? Or maybe just let me know what transitor is used on the differential circuits?

18th January 2007, 09:01 PM	#2
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	Have you checked for bad soldering ?? __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

21st January 2007, 10:08 AM	#4
JasonLee diyAudio Member Join Date: Jan 2007	harman Kardon shot noise Spend the who;e sunday afternoon to replace & swap some of the 2SC3200 (Swap) 2SA1268 (Replace new) problem is still on the right channel. But when I shake thr 2SC3206 before the protection circuit come into action. The right ch noise seems stop & then comes back. Will do a AB swap use the same transistor from left ch & see if the noise goes to the left.

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19th January 2007, 04:04 AM	#3
JasonLee diyAudio Member Join Date: Jan 2007	Alreay checked & resolder all suspect joints.

4th February 2007, 03:48 PM	#5
JasonLee diyAudio Member Join Date: Jan 2007	While i do a left-right swap of the 2SC3206. Accidentaly i cause some short circuit between the legs of transistors. Causing two resister burned. (R227-R & R229-R). I dicided to stop till I get all transistors & resister before I work on it again.

12th February 2007, 05:11 AM	#6
JasonLee diyAudio Member Join Date: Jan 2007	Finally I got this AVI-150 sing again. The shot noise is from the 2SC 3206 (Driver).

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