philips cd104 tda1540 NOS modify error...

[poki921]

Dear all
I've modified my philips cd104 to NOS mode
It works normally at first
But after two hours the sound sounds twittered and noisy.
Here are three pic attached
With playing the testing cd I made that produce continuous 1k wave
The first two picture are from left and right from cd104 after the op I/V
The last one is the normal result by my cd 304mk2 .







Thx!!

 

[JonSnell Electronic]

Check the steel feed through pins on all pc boards.

 

[poki921]

Check the steel feed through pins on all pc boards.

checked! I've re-soldered them all and put a cooper thru inside.

 

[rfbrw]

Try using freezer spray.

 

[poki921]

Try using freezer spray.

Don’t get the point??

 

[JonSnell Electronic]

Try using freezer spray.

That will help to pin point a faulty component, if there is one.

 

[poki921]

I only use the freezer to test the oscillation of the IC before
Don’t know the methods to debug the failure of pcb

 

[canvas]

I've seen similar waveform before. It was due to the wrong bit length setting from the source, e.g. input 24bits stream into a 16bit DAC.

 

[poki921]

I've seen similar waveform before. It was due to the wrong bit length setting from the source, e.g. input 24bits stream into a 16bit DAC.

Ya same guess from me
Maybe there will be some signs by duo channel measurements

 

[poki921]

Sorry
Forget to mention that if replace the decorder PCB
Trouble fixed so the problems might be in the decoder board.

 

[poki921]

here is the wave form from saa7000 PIN14 CLCF and connect to TDA1540 PIN28
I can count it's 14bit
But.....should it be a square wave?

 

[rfbrw]

What does the signal look like when it is not connected to the TDA1540 ?

 

[poki921]

What does the signal look like when it is not connected to the TDA1540 ?

It looks the same

 

[rfbrw]

Can you undo the changes you made ?

 

[poki921]

Yes I can.
But It works for couple hours
So I don’t think it is the modified problem