Can yo help me to DIY fix my DAC? (the USB feature)

(** Do you have any USA source for those CM6631A boards? From China, there is a chance of arriving too late.... )
 
(** Do you have any USA source for those CM6631A boards? From China, there is a chance of arriving too late.... )

Sorry, I don't know. I'm located in Australia. You'll need to do your own searching/research.

The Chinese sellers may agree to a faster postage method at an additional cost.
 
so usb is not reporting home so to speak . being no expert on these things or any other things as it happens .
needs someone that knows how it is supposed to tick to advise further ... i mentioned a forum earlier that understand these things ... i am on a new learning curve now .
 
It really depends how handy/experienced/crazy you are! :)

The original USB chip and associated circuitry is located on the main PCB, rather than on a separate daughterboard with I2S wiring between the two. This makes it very, very tricky to wire the above board to the main PCB.

With some experimentation, you could determine where to connect the six wires as shown on the right hand side of the PCB. The datasheet for the original USB chip should shed some light on that. There could be some other quirks which pop up though.

Fine soldering skills will be required, as the solder pads on the PCB will be tiny and closely spaced.

s-l1600.jpg
 
Well, this is the DIY forum... As far as I can see, I need to:

1- Find a place for this board, it could be just on top of the original board, the unit is tall enought, and the board seems to be flat.

2- Connect the 4 USB wires from the original connector, to those 4 holes in this PCB next to the USB connector, perhaps with a short piece of shielded wire, scrapped from some broken mouse cable.

3- connect the "SPDIF" output, those 2 holes I see in this board, to the SPDIF input in th eoriginal board, with a piece of MIC shielded wire...

4- disconnect the power going to the shorted USB section on the original board, or remove the ICs.

It seems doable :idea: , the unit will look like original from the outside, and I don't mess with EEPROM things that I don't understand...

I'm not sure if I need to connect those "DATA" connections on the right of the pict.. Aren't this "USB to SPDIF" intended just to get USB input and send the output to that SPDIF connector?
 
Well, this is the DIY forum... As far as I can see, I need to:

1- Find a place for this board, it could be just on top of the original board, the unit is tall enought, and the board seems to be flat.

2- Connect the 4 USB wires from the original connector, to those 4 holes in this PCB next to the USB connector, perhaps with a short piece of shielded wire, scrapped from some broken mouse cable.

3- connect the "SPDIF" output, those 2 holes I see in this board, to the SPDIF input in th eoriginal board, with a piece of MIC shielded wire...

4- disconnect the power going to the shorted USB section on the original board, or remove the ICs.

It seems doable :idea: , the unit will look like original from the outside, and I don't mess with EEPROM things that I don't understand...

I'm not sure if I need to connect those "DATA" connections on the right of the pict.. Aren't this "USB to SPDIF" intended just to get USB input and send the output to that SPDIF connector?


The SPDIF outputs on the PCB are provided to enable the unit to function as a USB to SPDIF converter.

This should certainly work, but it does mean that you sacrifice the SPDIF input of the DAC as it will now become your USB input.

Using the I2S connections would allow you to retain the SPDIF input whilst also shortening the signal path (ie. the USB input would feed directly to the DAC stage, rather than feeding via the SPDIF input stage first and then the DAC stage). However, your proposal would be no different than adding an external USB to SPDIF converter which is what I was originally suggesting, so I say go for it! :)
 
How difficult will be to use those I2S connections?? I think I should have those connections at my board.
 
How difficult will be to use those I2S connections?? I think I should have those connections at my board.

Yes, you do. You will need to check the datasheet of the original USB chip so that you can identify which pins on the chip are the I2S connections. You'll need to then idenfity the corresponding solder pads on the main PCB, and then solder thin wires from the new USB board I2S outputs to the main PCB.
 
Update: I'm exchanging e-mails with "Savitech" (the SA9023 manufacturer), they are guiding me with this ! This people is really friendly, they sent me 5 free samples of the IC last year, and now they get involved with my repair. Much better service than the DAC seller...

They told me to disconnect the EEPROM IC from the board and try again (Y). If hat works, signing a NDA form, they will send me some EEPROM tool, (I don't know exactly what kind of tool).
 
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