Yesterday (friday) evening i finally had some time to find out what was wrong with the XTi4000 amplifier. First of all i shorted the input to the
power amplifier. At point 1 of the U10-A opamp (the output) i make a connection to the ground of the amplifier and the 'bang' noise was gone.
Offcourse there was also no audio sended to the amplifier.
I measured all the components round this circuit and replace the ones that i had in stock. But still no solution. After this i decided to shorted the
output from the DA converter to ground. When shorted the 'ch1 +' output to ground, the 'BANG' sound was gone. To try furter i remove
R52 and R18 for channel 1 input and R20 plus R17 for channel 2 input, all 6.34k resistors and routed the output for channel 2 from the DA converter
to the input of channel 1, offcourse i used some temporally 6.34K resistors (axial trough hole types) to replace R52 and R18.
Resulting the 'BANG' sound was gone and the power amp from channel 1 passes audio from the input of channel 2.
So it looks like the CS4272 converter has a malfunction, but i'm not shure because i do not have lot of experience with AD/DA digital audio converters.
Can it be something else like a non accuracy clock signal or something like that?
Just to test i shorted the analog inputs from the CS4272 to ground, but this doesn't affect the problem. So it looks like the analog circuitry is ok.
But there is something that i don't understand. The amplifier started with the muted circuits activated. The schematics says that this circuit is located
AFTER the input of the power amplifier. I compared switch times and signals with both channels with my 100MHz oscilloscope and a Fluke DMM. Both channels worked exactly the same, so i think this circuit works fine. But i dont understand how can passed the 'BANG' produced at the input with activated mute.
Thank you all!
Patlover1983Member Since 28 Jan 2011
Offline Last Active Yesterday, 06:36 AM
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