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γ3 On the Move

gamma3, gamma24 (plug-in for the γ3)

Re: γ3 On the Move

Postby amb » May 1st, 2016, 1:47 pm

What are these measurements? And where were the probes connected to? Just curious.
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Re: γ3 On the Move

Postby cobretti » May 1st, 2016, 5:16 pm

Probed directly across the caps on y24 board, as the picture says, C1, C11 and C7. Comparison between regular through hole caps and SMD.
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Re: γ3 On the Move

Postby amb » May 1st, 2016, 8:00 pm

OK, cool. However, I don't think the difference is significant enough to affect the performance of the circuit, much less cause it not to work (as was suggested in whomper's thread).
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Re: γ3 On the Move

Postby cobretti » May 2nd, 2016, 1:49 pm

Understood. p-p noise would have to be more brutal. I also managed to lower the VFD switching noise from 50mV down to 17mV adding 4.7uF ceramic cap soldered right on LCDuino connector J1 on pin 1 and 2.
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Re: γ3 On the Move

Postby cobretti » June 21st, 2016, 2:03 pm

This : http://www.amb.org/forum/gamma3-build-problem-t3218-80.html#p31391 maybe fixed the start up problem, but I still have the popping issue I couldn't resolve. I tried everything! No luck. I was changing registry setting all different combinations and it didn't do a damn thing. I swapped the SRC chip, checked all powers 5 times, run that thing on batteries..........no change. When I go from USB to SPDIF I get a nasty DC offset on DAC output. It looks like firmware issue. Everything else works flawlessly.
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Re: γ3 On the Move

Postby amb » June 21st, 2016, 2:09 pm

I don't know how the firmware could cause a DC offset...
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Re: γ3 On the Move

Postby cobretti » June 21st, 2016, 2:27 pm

I changed the SRC chip 2x. So this is the chip #3. If the firmware is good, they must have a faulty series of these chips. The popping noise I am getting is related to SPDIF PLL lock, my best guess. When I switch to this SPDIF input without anything connected to it, the USB cross-talks through the chip and sends BS data to DAC, they start popping and go to DC offset.
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Re: γ3 On the Move

Postby cobretti » June 21st, 2016, 2:33 pm

Changing the registry http://www.amb.org/forum/gamma3-on-the-move-t3237.html#p30620had no effect. Any combination. As if they didn't exist.
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γ3 On the Move

Postby amb » June 21st, 2016, 2:39 pm

It would have to be a VERY big crosstalk from USB to S/PDIF to cause audible noise, especially if the S/PDIF is not "locked". One thing you could do is to simply unplug the ζ1 to see if it makes a difference. If the problem persists, then you know it's not such a crosstalk at work.
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Re: γ3 On the Move

Postby cobretti » June 21st, 2016, 2:46 pm

Of course it doesn't help if I unplug the USB. Not crosstalk as such, but some internal running PLL problem. It's no good until the SPDIF input has something to lock itself on, such as plugged in CDplayer (even without playing). Once PLL locked and registered, I can shut the CDplayer down.
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