[sdiy] PCM1702 DAC fakes ? or not ??

[Jean-Pierre Desrochers]

I’m working on a Yamaha Clavinova CVP900

That has its right channel dead.. no sound.
The left channel is ok.
So, looking at the attached PDF file from Yamaha,

They stated that a common issue was found on PCM1702 DAC’s used
on the main digital board. Noise or no sound at all can be encountered.

I checked both DAC and, effectively DAC IC29 had no sound
to its opamp (pin 7 on IC43).

The only ‘I thought reliable’ source to buy a PCM1702 I found
was Syntaur USA at $36.95 each.

To make sure I ordered two. Ok.

So I carefully removed the bad IC29 and soldered a new one.

The result ? Now both channels were dead !!

I thought I could have done something on the main board
while replacing the bad chip.. So I desoldered it and powered back the unit.

The left channel only came back alive… Hmmm…
So I picked the second DAC I had left on hand and soldered it
on the board.. Again both channels dead !!!

So 2 things could be happening.

New Fake PCM1702 IC’s that load the common data buses (QCLK, WCLK) when installed
and keep the good DAC from working.. ?

Or the driving IC that brings QCLK and WCLK to both DAC’s
that is getting weak and drop when 2 DAC’s are installed (That I doubt).
By the way I had no way to check digital waveforms on both DAC’s
beacause they are placed underneath a big daughter board.

 

So what do you think about that ?

Hmmm. 



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