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Hi, Had assembled fresh Buffalo IIISE dac with Paul Hynes local shunt regulators set, Lucians WaveIO and tube output stage. Problem is: after power on, A.MUTE led blinks once and LOCK led powers on and stays (on i2S mode); if same on SPDIF - no led is working or blinks. That's with no signal. Also i get only hum from speakers: with or without signal. What might cause such dac board behavior? My system has a common ground - copper bar. So all grounds connected: IEC, DAC AND ITS HYNES PS, WAVEIO AND ITS HYNES PS, TUBE STAGE AND ITS TUBE PS, RCA. DAC PS gives ~5.24V, local regulators are set to 120ma by Hynes. Any ideas what and where to check? Thanks in advance.  Edited by user Wednesday, May 6, 2015 5:25:57 AM(UTC)
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I've found the following while once more reading the guide (ive red it almost a year before, while waiting for Hynes regulators..):
I have not yet connected the volume pot;
I dont remember doing anything with L5... what is is exactly? I left this untouched since i got the dac board.
Any of those two options might make the board act like in my post above?
Thanks.
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The DAC come with a pot out for the volume. In that kit is a shunt jumper for use when you have no put connected (along with the 3-pin header). Without a jumper in place, you will get no output.
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Thanks Brian for responce.
Vol.pot has no relation to my current issue. Though i installed it now:)
My suspision goes towards badly welded UFLs. As i disconnected all those, 'LOCK' is NOT ON anymore and 'A.MUTE' is ON. Same with SPDIF. This is how things should be normally with no signal, right?
Hum is still present on speakers. This makes me think i poorly welded UFLs on dac board and one or more of them have signal/ground short!?
Does this makes sence?
If yes, how should i remove those UFLs in best way not damaging the board?
Thanks.
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It's impossible to say what is causing the hum. It could be your output stage or a grounding issue. I don't think the hum is related to the I2S inputs, at least not directly.
Can you test the DAC in isolation? Meaning, without an output stage and chack for audio at the DAC outputs directly.
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Ok Brian, i'll try dac board with no output stage and let know about results
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Didnt try no stage yet, but found/corrected a mistake with ground in my stage (loose/bad weld). Now its completelly silent with no hum.
Still this hadnt changed situation with lock led on. But ive traced it to this: everything stays ok with D1 and D2 connected until i plug last DCK ufl cable. I plug it into dac board - still ok, but as the other end is plugged into waveio, i get same issue - after power on, lock led lits with no signal.
Do i still need to check board without the stage Brian? Or you have other suspisions?
Thanks.
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Well, the DAC is locking because it is detecting a bitclock.
Problems could be:
In the source (no output, audio volume turned down, driver issue, software problem, etc)
In the DAC (volume not shunted or turned down, check all regulator output voltages while running, while being very very careful)
In the output stage (no amplifying, etc)
You need to isolate the problem by testing the individual parts to figure out which one is not working.
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OK, the the LOCK led right from the start is a good thing. I thought wrong, about this led to go on when signal comes to dac.. Still need to figure out why i get no sound. Vol. pot is turned all the way up. I can hear by the level of very small hiss, that the pot is working. Regulators on dac board gives: all 3,3ones - 3.26V; 1,2 one - 1,16V. Are those ok? I'll keep searching further. Edited by user Wednesday, April 29, 2015 5:31:56 AM(UTC)
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Some update on my progress. Had checked everything again, even more: checked output stage (thought it came assembled and had to be pre-configured for ESS9018 dac chip as current source according my agreement with Mr. "Lampizator" himself). It seams some areas of stage came preconfigured for "current dac chip" while others were left for voltage type dacs. Particularly signal input section appeared wrong to me according the manual: "L-Pad" resistor input network. So this gave me confidence to disassemble my dac again, to try to fix those output stage "suspicions". While waiting for the parts, i did test Brian's recommendation, and tested dac board alone to output signal. And voila: everything works, like supposed to and i get normal sound. So now im fully sure - my lampizator tube stage is the problem. Today, some resistors are coming and i'll try to fix signal input section according manual. Does ESS9018 have 195ohm output resistance for one channel? Edited by user Tuesday, May 5, 2015 6:32:21 AM(UTC)
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Problem with lampizator stage solved. Now everything works.
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Originally Posted by: minionas  Problem with lampizator stage solved. Now everything works. What was the problem?
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Originally Posted by: DQ828
What was the problem?
There were several: Hum - found my own bad ground solder related to RCA ground No sound - a problem with a solder joint not fully soaked through whole pcb thickness and not reached bottom traces which led to not heating the tubes :) How i had not noticed it not glowing..i don't know, it must be due to number of testing, changing AC heating to DC and etc i guess.. Just measured the DC on top of PCB and not looked at the tubes not glowing:) After i got sound, it was very low level and distorted - this was due to strange resistor network combination on signal input section as i noted in my posts above. Now this is solved with shorting the series to signal resistors contacts and changing the parallel resistors value to 39 ohms. This makes dac chip act as current source and makes proper signal attenuation ratio of 5:1. So now music plays, with one strange issue: i get occasional strange noise coming from one channel. You can check if it is acting during music with changing the volume on integrated amp (it reacts to volume change and appears right after you touch the pot; or if this noise is in "calm" period, you can move volume up and down, nothing happens and you can just enjoy pure music). How this noise sounds..well its if you had a small bug in your ear before, as it moves near your eardrum, you get such mild drum scratching/brushing/touching sound...not very pleasant sound.. what might cause this.. one microtube on output stage? One of stage's 2 power supply tubes (i made a separate tubes supply for each channel)?
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