Crackling noise - Sansui AU101

Carlosraj · 17th January 2010, 10:57 AM

Hi everyone,

I am new to this forum and would greatly appreciate if anyone could assist me with this problem.

A friend of mine gave me an old Sansui AU101 amplifier to help him fix it. When I power on the amplifier and turn on the volume, even without an signal plugged in, it gives out a crackling sound from both channels and gets louder and louder. If I bypass the preamp and connect directly to the left and right power amp circuit, it works perfect. I have replaced all the small signal transistors(2SC871) and capacitors on the preamp board but the problem still exists. Pls advice, anyone. Thanks.

Tony · 17th January 2010, 12:14 PM

that is an old amp, make sure all contacts like volume controls are clean...if you can replace them, that will be a good idea...

Mooly · 17th January 2010, 12:22 PM

Service manual available free here,
HiFi Engine | Download Free User/ Service Manuals, Amplifier, Receiver, CD, Tape, Tuner, Video

If the noise reduces as you turn the volume down and is on BOTH channels might e worth looking at the PSU for the preamp.
A quick scope check should find a fault like that in minutes

poynton · 17th January 2010, 01:21 PM

This needs moving to solid state.

This section is for problems with the forum itself.

.

17th January 2010, 10:57 AM	#1
Carlosraj diyAudio Member Join Date: Jan 2010	Crackling noise - Sansui AU101 Hi everyone, I am new to this forum and would greatly appreciate if anyone could assist me with this problem. A friend of mine gave me an old Sansui AU101 amplifier to help him fix it. When I power on the amplifier and turn on the volume, even without an signal plugged in, it gives out a crackling sound from both channels and gets louder and louder. If I bypass the preamp and connect directly to the left and right power amp circuit, it works perfect. I have replaced all the small signal transistors(2SC871) and capacitors on the preamp board but the problem still exists. Pls advice, anyone. Thanks.

17th January 2010, 12:14 PM	#2
Tony diyAudio Member Join Date: May 2003 Location: Palatiw, Pasig City	that is an old amp, make sure all contacts like volume controls are clean...if you can replace them, that will be a good idea... __________________ http://www.electronicslab.ph/forum/i...?topic=32688.0

17th January 2010, 01:21 PM	#4
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	This needs moving to solid state. This section is for problems with the forum itself. . __________________ If it ain't broke, break it !! Then fix it again. It's called DIY !

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17th January 2010, 12:22 PM	#3
Mooly diyAudio Member Join Date: Sep 2007	Service manual available free here, HiFi Engine \| Download Free User/ Service Manuals, Amplifier, Receiver, CD, Tape, Tuner, Video If the noise reduces as you turn the volume down and is on BOTH channels might e worth looking at the PSU for the preamp. A quick scope check should find a fault like that in minutes

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