Zero DAC noise in left channel
Sep 4, 2008 at 11:18 AM Thread Starter Post #1 of 14

koruki

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Well after doing some reading I saw that the Zero DAC got a lot of good reviews from the people on headfi and went ordered one from china. It arrived all fine plugged it in and sounds great however there was interference in the left channel. very subtle sound a bit like the noise you get from wind blowing on a mic. It was on and off and later it stopped, but came back the next day. while fiddling around with it I noticed I could make it stop by holding it and applying pressure at the base of the unit (pushing upwards where the board sits) when I let go the noise would come back. The noise isnt a constant one and when music is playing I wouldn't notice it. But when I used my method of applying pressure to the base, the left channel would clear up and balance with the right channel.. So there is definitely something going on but cant figure what is causing it, for now in order to hear music without little pops and rattles on the left channel I have to hold the unit like I'm eating a burger.

I mentioned this problem to a friend who is studying engineering he said it might be related to capacitors. I've opened the unit up looked around under the board, cant find anything out of place. Very annoying hope some of you can help with your experience in audio equipment! thanks a lot in advance.
 
Sep 6, 2008 at 1:41 PM Post #2 of 14

koruki

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bump
 
Sep 6, 2008 at 1:50 PM Post #3 of 14

Meliboeus

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sometimes those hisses are caused by interferences in the mains, have you tried connecting the zero to a different output ? For example i could hear some hiss at full volume with my zero connected to the same slitter with my computer, now i've switched and it is dead silent...
 
Sep 6, 2008 at 2:19 PM Post #4 of 14

mwofsi

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Seeing I'm sitting around at home with a cracked rib and you've had no replies I might as well give you my thoughts.

Firstly, as you've just bought it you really ought to contact the supplier and give them a chance to put things right. Having got that out the way:

Your noise is possibly either a mechanical situation or interference.

Mechanical: maybe your headphone jack is making poor or intermittent contact with the socket for instance. Annoying and could be tricky to fix. moving the jack around and/or using different 'phones, (in other words a different head phone jack) might help or confirm this.
It could also be a poor connection somewhere within the unit. Do you really want to go poking your fingers around inside a mains powered unit? Capacitors are dangerous even once the unit is unplugged. It may even be caused by a dry solder joint on one of the boards.

Interference: could be situational. Something in the surroundings causing electromagnetic interference, you holding it in a certain way disrupts this. Try it in another room away from fancy lighting and computers (!), seriously I don't know the possible radiation sources but someone far more knowing than I suggested something similar, and it's something that can be tried.

How did I crack a rib: fell over running for a bus. I'm a bus driver...... It's not funny......
L3000.gif
 
Sep 7, 2008 at 7:55 PM Post #5 of 14

Pricklely Peete

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Pull the main pcb and check for sloppy clean up on solder, possible shorts, unclipped parts leads.....that isn't the norm for production units..but a few have made it past QC with these issues. Another thing to check for is fully seated opamps and the ground wire to the volume pot casing may not be making good contact.

Peete.
 
Sep 7, 2008 at 9:50 PM Post #6 of 14

AudioPhewl

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Any chance of this being a poor solder joint to the rear RCA sockets? Have you tried listening to music whilst applying small amounts of pressure to the leads?

If the noise is coming from the headphone stage as well, then this isn't going to be the answer IMO...

~Phewl.
 
Sep 7, 2008 at 11:40 PM Post #7 of 14

koruki

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I've experimented and its def not the headphone jack cause the board for the plug is seperate and I am applying pressure the mainboard. I might post some pictures. Thanks a lot of the help guys
 
Sep 16, 2008 at 3:42 AM Post #8 of 14

koruki

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Well I've narrowed the problem to the wire that runs from the board to the headphone jack. I noticed that one of the wires has a damaged/defect sleeve.

So what are my best options? Any advice is much appreciated thanks a lot. If pictures are essential I will try to get a hold of camera

pic1.jpg

pic2.jpg

pic3.jpg
 
Sep 16, 2008 at 4:59 AM Post #9 of 14

mwofsi

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Nice pictures and well done on the fault finding.

The white part that the red and white wires run into is probably a socket. It may be possible to remove it from the board in order to repair it. It may have some form of latching mechanism holding it to the board, it might be friction or it might be some sort of evil/fiendish mass production technique that's a real pig to remove.

The wires were probably connected to the socket by first having a small sheet metal terminal mechanically clamped to the wire and then the terminal's inserted into the socket. If you lucky and careful you may be able to remove the wire/terminal without damaging the socket and carefully reclamp the (loose) terminal before re-inserting it. Phew
darthsmile.gif
 
Sep 16, 2008 at 5:31 AM Post #10 of 14

koruki

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Quote:

Originally Posted by mwofsi /img/forum/go_quote.gif
Nice pictures and well done on the fault finding.

The white part that the red and white wires run into is probably a socket. It may be possible to remove it from the board in order to repair it. It may have some form of latching mechanism holding it to the board, it might be friction or it might be some sort of evil/fiendish mass production technique that's a real pig to remove.

The wires were probably connected to the socket by first having a small sheet metal terminal mechanically clamped to the wire and then the terminal's inserted into the socket. If you lucky and careful you may be able to remove the wire/terminal without damaging the socket and carefully reclamp the (loose) terminal before re-inserting it. Phew
darthsmile.gif



Actually its worse lol. The clamp its on goes straight through the board and is soldered under it. I thought about snipping the white damaged wire and soldering straight to base but seems a bit nasty lol
 
Sep 16, 2008 at 5:40 AM Post #11 of 14

mwofsi

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In that case it's probably time to brush up on your desolder technique. Remove with desolder braid as much solder as you can from each of the four pins before gently wiggling and trying to remove the socket as you pass your iron over each of the pins in turn.

Else cut into the socket with an x-acto knife and solder the wire to the terminal. And don't forget the flux in either case.
 
Sep 16, 2008 at 6:09 AM Post #12 of 14

mwofsi

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It should also be possible using similar techniques to replace the supplied socket/plug with a shop bought header and socket/terminals. It's quite awkward to get a good crimp of those terminals onto a wire even with a proper crimping tool. Industrial crimping tool versions probably have a higher success rate.
 
Nov 21, 2008 at 5:03 AM Post #13 of 14

koruki

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Update: I desoldered the original cable and threw it out and put in one i picked up from local electronics store for 30 cents. The sound is now totally clean!!, i solder straight onto the board didnt bother with the sockets.

at 30 cents a meter i only used 10 cm's so that was a 3 cents repair haha.
 
Nov 21, 2008 at 6:20 AM Post #14 of 14

bundee1

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congrats man! Your perseverence and ingenuity paid off. Thanks for sharing the solution.
 

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