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Old 15th December 2010, 04:05 AM   #1
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Join Date: Jul 2010
Default Need some help


I'm new here. I would really appreciate some help.
An acquaintance of mine, (who is quite good at DIY Audio) built me a DAC off of the Gigawork Upsampling DAC with CS4398 DAC, up-sampling chip, and R-Core transformer.

It was a work of art.

He made several modifications to the board - including: bypassing the second op-amp, upgrading the op-amps, making a different LPF, changing out some output capacitors from stock, etc. I can get you more detail if it would help. Needless to say he did most of the changes that were presented on this forum except for the transformer outputs. He stayed with the op amp design. We ended up using BB 627 single chips on a converter board - for stereo output. He also put a synchronization light on the front case along with a switch to change from Toslink, Coax, USB. The case was much bigger than needed but steel with standoffs. (Once again - all quality work)

This thing worked flawlessly on both my HTPC and as an upgrade to an older Sony ES CD player via Toslink. It sounded as good as it looked.

I mean this guy does outstanding work and it shows.

One morning I was playing a CD just fine, then I put a different CD in and all of a sudden no audio output. I checked everything - my amp, cables, etc. This didn't make sense. I didn't change anything. Just changed the CD. Now I know it was just coincidence.

So - I didn't panic and read that others had had bad up-sampling daughter boards. If that board fails, no audio output. I thought for sure that was the problem. So I removed the board and put the proper jumpers on all pins except for GND and 5V. Still no audio output.

I then thought that maybe the op-amp went bad. Changed it out with another stereo NS 49710 opamp that he had built for me. Still no change.

The problem is I can't get hold of the guy who built it for me. I can't return the board as it has been highly modified, and I can't figure out what happened to the audio outputs. I don't know what happened to the guy but I have been unable to get hold of him for over 6 weeks now.

I do know that the board still synchs to both a CD and USB signal. (The front synch light lights up when it get's an input) - so I figure the receiver chip is still working? The USB light on the board lights up when plugged into a live PC. I also see that all power lights on the board are lit - so I would assume it's not a bad R-Core transformer - although I haven't measured voltages to the input of the board.

I just don't know where to go next. I am hoping you guys could point me in the right direction. I am pretty handy with electronics - but am not an expert with DAC circuits by any stretch. My son is an EE and is coming home for Xmas and I have a good multimeter for testing.

Could this be a bad DAC chip itself? Should I be checking his output modifications? Did something else go out on this board? I don't see anything obvious - nothing looks burnt and there are no electrical smells of any kind. This just totally baffles me!

Any advice on what to test next would be greatly appreciated.

I hope I got to the right board - if not, I apologize as I am new to these forums.

Thank you in advance for any help you could provide me. I invested a lot in this project and hate to just throw it all away. I'd be willing to send any other information or details you may need in helping me troubleshoot this.

Once again, I would be grateful for any advice.
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Old 15th December 2010, 06:24 AM   #2
Maniac is offline Maniac  Taiwan
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Sorry, wrong board/vendor. Even if someone is going to try their darnest to help, it would be really hard as you have mentioned that it is highly modified, and doing diagnostic over the forum is not going to be easy.

One suggestion I have is to send 60Hz signal to your DAC, and measure if there are any analog output at all. Since 60Hz signal is going to be easy for the multimeter to pick up (just set it to AC voltage), and you can see if there are any analog output and it there are, where in the chain did it broke.

Just out of curiosity, did you put the original CD back in when it first happened?
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Old 16th December 2010, 02:00 AM   #3
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What board should this be posted to? Can anyone help me here?

I just ordered another DAC chip - but feel I'm running blind here.

I don't see anything on the DAC board that would indicate anything is wrong.

This is very frustrating.
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Old 18th December 2010, 02:53 AM   #4
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I don't get this forum. I ask for help and nothing.

I guess because I am a noob - I don't warrant any help from anyone?

Could someone PLEASE point me in the right direction here?
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Old 18th December 2010, 03:07 AM   #5
tinitus is offline tinitus  Europe
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moved your thread
hope it helps

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Old 18th December 2010, 03:11 AM   #6
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Thank you - were did you move it to?

Sorry to be so dumb.
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Old 18th December 2010, 03:13 AM   #7
tinitus is offline tinitus  Europe
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look at top header, says Digital Source
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Old 18th December 2010, 03:25 AM   #8
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OK - now that I am on the right thread - sorry about that - I will give you an update.

I contacted Ian at Gigawork. (The vendor that sold the board to the DIYer who built this for me. Ian via e-mail suggested that I re-seat the DAC board and take off the upsampling board to see if it is defective. I took off the up-sampling board twice and jumpered it properly to no avail.

Stupid me - while I was pulling off the DAC board I bent two pins. While trying to straighten them out (carefully) I broke two pins off. Does anyone have a suggestion on how I can solder two pins back on? I can't find the broken pins. I have bought solid wire as small as 20 gauge but it is still too big to fit in the socket. I can't seem to find a wire this small to re-solder the broken pins.

I can't seem to communicate with this Ian Chinese guy. First he says he will send me a new DAC if I send him $35.00. I sent him payment via paypal - the next thing I know he is refunding me back. The guy has terrible customer service and does not seem to be interested in anything but selling new boards. You are lucky to get a response from him every two days. And when he does respond he makes no sense.

BUYER BEWARE that if you purchase one of these boards from him and have a problem you bill be on your own. He has NO interest in servicing you and only wants to sell new boards - where the quality is very suspect.

In the meantime - I am in desperate need of help. First - I would like to get the DAC chip back in - but don't know if or how I can get these two pins back on the socket. I'm sure someone here has done this before. I have pretty good soldering skills - but don't know the best way to get the two pins back on and in the socket.

The guy who built and modified the DAC will not respond to me. I feel totally screwed.

I'd be happy to send it to one of you and pay you if you would be willing to help me fix it. I have spent over $300 on this project and have nothing to show for it. It worked perfectly for the first couple of weeks but then just died one morning.

If someone would like to buy this from me for parts - please send me an e-mail at I'd be happy to work something out with you as I'm just trying to recover some of my loss here. The case alone is worth over $100.00.

I'd be in debt to anyone willing to help me.

I'm a stupid noob sucker for ever getting into this situation. I should have never ventured here and have learned a good lesson.
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Old 18th December 2010, 03:26 AM   #9
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Thanks - just posted an update to my situation. Would appreciate it if you would post that as well.

I appreciate any help I could get here.

Thank you so much again.
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Old 18th December 2010, 07:03 AM   #10
Mooly is offline Mooly  United Kingdom
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Perhaps if you could post some pictures of the problem socket/pins etc. You talk of a DAC board and then a DAC chip.

All fault finding has to be logical... you can not guess. You say the thing failed while in use... so you need to check all the supplies for a start (and that means ALL) to all the IC's.

And with the greatest respect please remember you are asking for help on something that some one else built, and then modified, and now you have had a look and broken something.
That's not a good combination
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