Non working DAC

[Paco]

Hi all,
I have a CEC DX51 dac that a friend gave me because it doesn't work. I have no idea of digital electronics. The dac looks perfect, I connect it and there aren't any problem. It's a modular system and the DAC section uses four BB PCM1704 chips. When I play music trought it I can only hear some kind of white noise. Any ideas?

Best regards,
Paco

[rfbrw]

What chip lineup does it use i.e SPDIF receiver, digital filter etc ?

[Extreme_Boky]

Check if the input SPDIF connectors' middle pin(s) are soldered to the PCB. Is there an LED for "signal lock"? Is it on when you press play on your CD mechanism / player?

Extreme_Boky

[Elso Kwak]

Originally posted by Paco
Hi all,
I have a CEC DX51 dac that a friend gave me because it doesn't work. I have no idea of digital electronics. The dac looks perfect, I connect it and there aren't any problem. It's a modular system and the DAC section uses four BB PCM1704 chips. When I play music trought it I can only hear some kind of white noise. Any ideas?

Best regards,
Paco

No idea of digital electronics and trying to repair? Hey ho!
First check all powersupplies for correct voltages and inputconnector for bad contact especially when soldered directly to the PCB. Have a scope ? Odd question, yes??

[Paco]

Hi all,
Thanks for your replies.
More info: I’ve used the coaxial and the “superlink” (a CEC proprietary connection that uses a RS232 cable) and none of them work make the DAC work correctly. The noise is different when using one or the other conection (there’s more noise with the coaxial) but no music at all.

What chip lineup does it use i.e SPDIF receiver, digital filter etc ?

The decoder module uses CS8414, the digital filter uses BB DF1704E and the DAC uses 4 BB PCM1704. I can send photos if it could help.

Check if the input SPDIF connectors' middle pin(s) are soldered to the PCB. Is there an LED for "signal lock"? Is it on when you press play on your CD mechanism / player?

Hi Extreme_Boky, at a first glance, it looks ok. When I play music the led “play” on the DAC turns on but I only have noise at the output.

No idea of digital electronics and trying to repair? Hey ho!

Hi Elso. I just wanted to see if I could see something wrong and I couldn’t. If I can have an idea of where’s the problem from someone who knows about digital electronic there’s a possibility to repair it. If I can’t solve the problem I’ll order a DAC and use the housing and the PSU’s components to build a new DAC.

First check all powersupplies for correct voltages and inputconnector for bad contact especially when soldered directly to the PCB.

I’ll do it.

Have a scope ? Odd question, yes??

I don’t have a scope but I have an ATB Precision measurement equipment (that I use to design loudspeakers). I know that it has a 2-channel Oscilloscope with FFT Analyser and 100khz of max sampling rate, but I have no idea of what should I measure in a DAC, so this function is mainly useless for me right now.


Thanks for your help!
Regards,
Paco

[rfbrw]

If you haven't already done so, download the datasheets for the CS8414, DF1704 and the PCM1704. Having done that you can then check to see that all the voltages are present and correct.
If all the voltages are correct the next step would be to test the CS8414. With the SPDIF disconnected test pin25.It should be high. When you reconnect the SPDIF pin25 should go low indicating signal lock

[Paco]

Hi rfbrw,
Thanks for the info. I'm overcrowded with work at the moment (weekends included) so it's difficult to me to make tests. I've found replacements for the DAC board in ebay very cheap and I've ordered one of them to replace the existing. I think that the problem is here, but I'll be sure shortly.

Best regards,
Paco

[adsiuksles]

Hi all,

I have problem with CEC DX51 too. Theres is no sound in the right channel, left is full working. Maybe some of you have any ideas, or can help me to find technical manual?

Thank you!