I successfully replaced R53 and lifted pin3 on U16, just needed a little whiskey to steady my hands
Voltages (in reference to TP0) are now:TP1: 6.86V
TP2: 9.93V
TP3: 5.00V
TP4: 2.49V
TP9: 12.40V
TP10: 11.15V
TP5: 10.03V
TP6: 1.88V
TP7: 3.61V
TP8: 12.02V
Voltages are all close to expected values except for TP6 and TP8.
Cool, thanks. That is indicative that its the opamp which is at fault, not the cap.
My suggestion to get you going on this is to ask Mouser to send you an LT1028CS8 to replace the faulty one you have. Also some 15R resistors in case the one you desoldered got damaged. Are you OK with this? Mouser seems to be having some delays so it could be several days before you receive the part. In the meantime only the L channel of your DAC will work.
TP6 is out of spec because the opamp's broken but TP8 looks reasonable given its being fed with an out-of-range input voltage.
My suggestion to get you going on this is to ask Mouser to send you an LT1028CS8 to replace the faulty one you have. Also some 15R resistors in case the one you desoldered got damaged. Are you OK with this? Mouser seems to be having some delays so it could be several days before you receive the part. In the meantime only the L channel of your DAC will work.
TP6 is out of spec because the opamp's broken but TP8 looks reasonable given its being fed with an out-of-range input voltage.
Fine by me, I'll be looking forward to receiving the replacement parts. Thanks for your support, hopefully replacing the opamp works as we expect!
Hi @beardman
I'm curious to know in what way the DAC's sound surprised you. And what DAC(s) you've been listening up until now which formed your expectations?
I'd be paying attention to what's feeding these supplies as the transformer can make quite a bit of difference to the common-mode noise. Are those supplies being fed by a split-bobbin EI trafo?
I'm curious to know in what way the DAC's sound surprised you. And what DAC(s) you've been listening up until now which formed your expectations?
I'd be paying attention to what's feeding these supplies as the transformer can make quite a bit of difference to the common-mode noise. Are those supplies being fed by a split-bobbin EI trafo?
To be honest, upon receiving the kit I was carried away by emotion and began to solder the capacitors from step 2 instead of starting from step 1. My head interpreted that I had to start there. Big mistake. When I found out, I removed all the capacitors (it was the only thing I had soldered). The point is that after removing the capacitors, there is a little tin left in the holes.
Could it be that this tin influences the measurements I am taking after completing step 1?
Could it be that this tin influences the measurements I am taking after completing step 1?
Looks to me there are potentially two problem areas. TP4 is much too low - could be a short or open in soldering U3 (CJ431) or could be a solder splash around U2. To dig deeper, measure the voltage across R17.
TP9 is too high by a large margin (increasing the zener currents substantially which drags up TP1, TP10) which makes me wonder whether D6 has been soldered with the correct polarity. Please check that the band marking (K) is towards L1 (ferrite bead).
I have changed the polarity of 1N4001F and now all my measurements are correct, except for TP4 which is still at 0.64v. I have soldered and desoldered the CJ431 several times and it remains the same. In fact, the measurement of the TP4 was the same without the CJ431 soldered to the board. I have checked the welds on U2. What could be the problem? Greetings and thanks.
Hi Abraxalito,
This may have been already asked, but I can't find where:
Does your dac has a clock or relies on a external clock coming from i2s?
Do you think there is a benefit to have a good clock - I am thinking about something like
"The Well Tempered Master Clock" - from another thread here.
I am going to start soldering the parts soon, but already thinking ahead.
This may have been already asked, but I can't find where:
Does your dac has a clock or relies on a external clock coming from i2s?
Do you think there is a benefit to have a good clock - I am thinking about something like
"The Well Tempered Master Clock" - from another thread here.
I am going to start soldering the parts soon, but already thinking ahead.
My best guess is you have U2 soldered in upside down. Check the photo below, the bevel on the SO-14 package goes on the left, the side of the white dot on the PCB silkscreen.
Attachments
Hi Youri - the DAC doesn't have its own clock, it gets it from BCK (bit clock) on the I2S input. Normally that's at a frequency of 2.8MHz (64 times the sample rate of RBCD)
Its a good idea to think ahead but also bear in mind that the clock can't easily be separated from the data its there to serve. If you have a source component for the data (e.g. a CD player) then the rate the data is sent out is determined by the clock inside the player. Putting another clock at the DAC won't help unless that clock is slaved to the CD player's clock.
The way to get the best clock where it matters (at the DAC) is to put the good clock right at the input to the DAC, not in the source component. I think the easiest way to achieve this is get yourself an SDcard player. I recently shared one on the 'technical' thread for lingDAC - on that player you have easy access to the clock so it shouldn't be too hard to feed that from a good clock right at the DAC.
lingDAC - cost effective RBCD multibit DAC design
Having said all that I so far haven't considered clock quality to be a major factor in DAC SQ. As I progress though perhaps I'll realize its the next bottleneck....
I'm curious - I saw you just put it up for sale on Swap Meet. Got fed up with how it sounds?
it is a little tricky,,,overall i really like the sound,,,but in my setup,,things going to be
to warm,,,my tube pre and amp playes on the warm side,,
my normal dac playes more hard,,,it went out to be a better mach,,,
it had nothing to do with bad sound from the phideca,,,it playes really good,,but still on the warm side
if i had a more cold playing setup,,, there was no doubt what i will use
hope this give a explanation why i must let it go,,,
to warm,,,my tube pre and amp playes on the warm side,,
my normal dac playes more hard,,,it went out to be a better mach,,,
it had nothing to do with bad sound from the phideca,,,it playes really good,,but still on the warm side
if i had a more cold playing setup,,, there was no doubt what i will use
hope this give a explanation why i must let it go,,,
Hi Abraxalito,
and thanks for this dac.
I've received it few days ago but today only I've had the opportunity to switch it on.
Phideca dac is connected to I2SoverUSB v.III .
No fancy power supply, original output capacitors in place.
To make the story short, I'm more than surprised about the dac performance: awesome!!!
Sound is full bodied, may be warm but on good side. Really, really happy with that.
My next step will involve replacing output capacitors and feeding with better power supplies.
Thanks again for such a high level product.
and thanks for this dac.
I've received it few days ago but today only I've had the opportunity to switch it on.
Phideca dac is connected to I2SoverUSB v.III .
No fancy power supply, original output capacitors in place.
To make the story short, I'm more than surprised about the dac performance: awesome!!!
Sound is full bodied, may be warm but on good side. Really, really happy with that.
My next step will involve replacing output capacitors and feeding with better power supplies.
Thanks again for such a high level product.
As you said, it was upside down. I have changed it. Now the TP4 voltage is 2,74v. instead of 2.5v.
Is it acceptable?
I think your CJ431 (U3) may have gotten damaged from all that extra soldering iron attention it has received. I believe we sent a spare one in the kit, best replace it.
@cixio: Thanks a lot for your feedback, great that you're enjoying how it sounds.
@beardman : I had a thought - you could try your DAC with the 3rd order filter to add a little 'coldness'.
@cixio: Thanks a lot for your feedback, great that you're enjoying how it sounds.
@beardman : I had a thought - you could try your DAC with the 3rd order filter to add a little 'coldness'.