Heavy “whoosh” sound from Left channel KA-9100

[angelaudio]

Hey folks I recently put my KA-9100 in the main system and noticed it was making a heavy ‘whoosh’ sounds from the left channel. It almost sounds like tube rush but louder. The right channel is unaffected. I did some basic troubleshooting as follows:

1) Flipped the ‘Reverse’ switch to swap channels but sound stayed in the left speaker.
2) Connected speakers to both A and B and issue still persists.
3) Reversed speaker connections at the back, issue persists.
4) When i flip the +10db switch the sound gets louder
5) When i flip the -10db switch it gets quieter
6) Turning volume all the way up does not make the sound louder
7) Turning volume all the way down does not decrease the sound

Any ideas what could be going on? T.I.A.!

 

[eizner23]

Congratulations! You may have a faulty small signal transistor. A quick and dirty way to check if its in the preamp- switch to separate on back and plug another preamp or carefully your phone with volumn down, report back if the problem persists.

 

[angelaudio]

Congratulations! You may have a faulty small signal transistor. A quick and dirty way to check if its in the preamp- switch to separate on back and plug another preamp or carefully your phone with volumn down, report back if the problem persists.

Problem gone. So the faulty small sig transistor is in the preamp section? Thanks for the help

 

[OMGCat!]

If it goes away with another preamp that would mean the noise is coming from the pre.
Look over the schematic and get yourself a can of freeze spray (or use a can of duster turned upside down). Spray a tiny bit of the cold juice on one transistor at a time (with about 30-45 seconds between) to see if the noise gets worse or goes away. Many times noisy transistors will react to big temperature changes so this can be a quick way to isolate the problem.

 

[angelaudio]

If it goes away with another preamp that would mean the noise is coming from the pre.
Look over the schematic and get yourself a can of freeze spray (or use a can of duster turned upside down). Spray a tiny bit of the cold juice on one transistor at a time (with about 30-45 seconds between) to see if the noise gets worse or goes away. Many times noisy transistors will react to big temperature changes so this can be a quick way to isolate the problem.

I’ll give that a shot and report back with results. Thank you