I do not understand the purpose of U6 in conjunction with P7 and the input selector. The input selector has four positions but as far as I can see P7 only accommodates three inputs (P7 pin pairs 15/13, 11/9, 7/5). What is the purpose of P7 pins 1/2/3 and U6? I can see that pins 1 & 2 could be used to provide power to say the optical input or something similar, but the purpose of U6 evades me.
The LX45 is the FPGA that also works if I remember correctly. I would also need the JTAG cable (is this the right one)...
JTAG cable
Anything else required to use the LX45?
JTAG cable
Anything else required to use the LX45?
A computer running the free (WebPACK) version of Xilinx ISE. I use ISE 14.6, the latest is ISE 14.7, I think Sonny used ISE 14.7. The JTAG cable is the same model I'm using.
The only part of ISE that you really need is iMPACT, the programming part, but I don't think you can install it seperately.
The only part of ISE that you really need is iMPACT, the programming part, but I don't think you can install it seperately.
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The Mouser order can wait a minute.
Just flooded one side of J4 with solder and wicked it away as lightly as possible, checked for shorts, cleaned a few up, placed the FPGA back in the socket and turned on the dac and ALL the switches now operate as intended. Marcel, looks like you may have been correct about some lightly soldered legs on that side...there has certainly been a fair bit of solder wick over them during this debug process and I may have been a little too throrough.
Phew.
Still no sound from either SPDIF input. But after plugging in the I2S from the JLSounds board I have sound! Very, very quiet though. Am thinking that the Soft-Medium Loud switch is not hardwired correctly and that loud should be SW4.1-gnd, not SW4.3-gnd. Will give it a go now to check.
Excited!!
Just flooded one side of J4 with solder and wicked it away as lightly as possible, checked for shorts, cleaned a few up, placed the FPGA back in the socket and turned on the dac and ALL the switches now operate as intended. Marcel, looks like you may have been correct about some lightly soldered legs on that side...there has certainly been a fair bit of solder wick over them during this debug process and I may have been a little too throrough.
Phew.
Still no sound from either SPDIF input. But after plugging in the I2S from the JLSounds board I have sound! Very, very quiet though. Am thinking that the Soft-Medium Loud switch is not hardwired correctly and that loud should be SW4.1-gnd, not SW4.3-gnd. Will give it a go now to check.
Excited!!
If your amplifier has an unbalanced input, did you ground the negative side of the secondary winding of the DAC's output transformer?
Could you measure what level you get when playing a 0 dBFS sine wave, with the negative output of the transformer connected to the ground of your scope and the positive side to the probe tip? It should be around 1 V RMS, so about 1.4 V peak.
Could you measure what level you get when playing a 0 dBFS sine wave, with the negative output of the transformer connected to the ground of your scope and the positive side to the probe tip? It should be around 1 V RMS, so about 1.4 V peak.
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Marcel,
The WaveIO appears to have a mute connection: http://www.luckit.biz/documents/WaveIO/WaveIO_Infos.pdf
At the bottom of page 1, section 4, L8 sounds like it could be connected to pin 3 of P9 for the mute functionality. Does that sound correct?
The WaveIO appears to have a mute connection: http://www.luckit.biz/documents/WaveIO/WaveIO_Infos.pdf
At the bottom of page 1, section 4, L8 sounds like it could be connected to pin 3 of P9 for the mute functionality. Does that sound correct?
Yes, unbalanced input to the preamplifier, and no, the OPT secondary has not been tied to ground. Should I? Can test it with clip leads I suppose.
Will search for a 0dBFS sine wave file to play...wonder where Roon Radio will go after that track?? Haha.
It's a floating output, so yes, you have to connect the negative side of the secondary winding to ground when driving an unbalanced input. You'll see why when you draw a schematic of the secondary winding and its the input impedance of the amplifier and wonder how the return current has to flow.
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Marcel, see the attached image. Left channel is reading about half of the right channel which is circa 2.8V peak to peak.
Initially this was reading 20mV P-P for left channel and about 40mV peak to peak for the right channel, but the filter pcb's I have here have a problem with the soldermask and are quite sketchy to solder to so after all this yanking about debugging the main pcb I decided I had a questionable joint or two so I hardwired the filter (soldered wire to the component pins/tabs). The pcb fabricator is aware and insists that the gerbers are at fault but I have not bothered following it up considering I am not using the Jensen transformer (using a Slagle OPT). Re-wiring got me my volume, as you can see in the image, but for some reason the left channel is about 3dB down from the right channel.
Am listening to Bruckners 8th right now with the preamp balance set all the way left to even the channel volumes.
Would a failed filter capacitor cause this Marcel? Given that C51 failed earlier perhaps there is one on the filter board that has also shorted. Not sure. Is also a lot more noise of the left channel than the right.
Attachments
That is, a short in either C28 or C29 on the main PCB or some short in parallel with one of them would halve the left channel's signal and much increase its noise. Are the DC levels at the anodes of U1A, U1B, U28A and U28B all about the same (some -28 V)?
In retrospect I regret that I haven't either included solder mask or used a larger spacing to the ground fill/ground plane (or both) on the filter PCB. It's now unnecessarily hard to solder without getting shorts to ground.
Great that you can listen to Bruckner now!
In retrospect I regret that I haven't either included solder mask or used a larger spacing to the ground fill/ground plane (or both) on the filter PCB. It's now unnecessarily hard to solder without getting shorts to ground.
Great that you can listen to Bruckner now!