[orenskl]

Hello,


I have been enjoying my AKSA55 for several month now, until recently one of the channels started making strange noise when I switch the power off, instead of the usuall low volume soft "thump" I am getting a very loud crack from the right channel, I have started talking to Hugh about this but lost contact since his ISP connection is gone .... but at least Hugh confirmed that all my DC readings are OK.

One thing I was able to find out is that when I connect the input pins (signal and GND) together and short them to ground this "switch off noise" goes away. I have tried re-soldering all the input components (incl T1 and T2) but this did not help.

I am pretty lost in the dark, if anyone can help I would appreciate that.

Thanks

Oren

[AKSA]

Hi Oren,

I'm baaaccckkkkk!!

Not a very good service, I'm complaining bitterly, we will see what happens....

I've just had an idea.  I suspect your input cap might have gone leaky, hence noisy.

Try replacing it temporarily with a junkbox 470nF, see if the cracking noise goes away.

You might also resolder R1, the 47K bias resistor on the T1 side of the input cap.  It's possible that this resistor has a dry joint.

Hope this helps,

Cheers,

Hugh

[orenskl]

Hi Hugh


Thanks for geting back to me.

I replaced both C1 and R1 and get the same results.

Oren

[AKSA]

Hi Oren,

Hmmm.  This is getting quite tricky.....

Try this;  resolder the voltage amp and the Rbe of the voltage amp (T3).  Then remove the bootstrap cap, the 100uF in the center of the pcb.  Now try turning it on and off, see if there is still a loud crack.

If no, replace the bootstrap cap, if not, put the old one back in as it's clearly OK.

Now I've reliable coms, just email me with the continuing saga!!

Cheers,

Hugh