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γ3 On the Move

gamma3, gamma24 (plug-in for the γ3)

Re: γ3 On the Move

Postby amb » March 7th, 2016, 7:45 pm

Hmm. Good point. It seems that all occurrences of this issue are on builds with VFDs. I recall that early during my own build with a VFD, I had a similar problem. But the display died and I changed back to an LCD. I never encountered the clicks again but didn't make an association with the change of display.
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Re: γ3 On the Move

Postby whomper » March 8th, 2016, 12:22 pm

I too have the popping sound (have VFD). it starts with USB audio playing while selecting a different input. From that point, stopping USB audio does not stop the popping noise.

I have also reported this in my other y3 thread and if memory serves me right, I had an LCD at that time.


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Re: γ3 On the Move

Postby cobretti » March 8th, 2016, 12:58 pm

Yes, I am using VFD. I also noticed that once other channel is turned on, for example my CDP coaxial , the DAC kind of "locks on" to that other input and everything is quiet. I don't even have to play any music from CDP, once I turn it on, the DAC gets quiet, no popping noise. It is a bug. I don't see why this would be power related or VFD related, unless the switching noise from VFD is changing some registry data in ATMEGA328P micro. It shouldn't get pass the isolators all the way to SRC4392 to change the data or do anything over there.
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Re: γ3 On the Move

Postby cobretti » March 8th, 2016, 1:02 pm

Maybe the VFD is poorly decoupled. I will have to have a look at that Newhaven crap. To be honest, I don't trust it much. This is the VFD #3 I got from DigiKey and all 3 are(were) iffy.
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Re: γ3 On the Move

Postby hagak » March 8th, 2016, 2:15 pm

I love the look of VFD displays but between switching noise I hear on a number of them and the sometimes not so great life expectancy I decided to stay away.
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Re: γ3 On the Move

Postby cobretti » March 8th, 2016, 2:39 pm

There is a nice square wave 215KHz switching noise on the power rails coming right from the high voltage VFD. About 10mV p-p.
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Re: γ3 On the Move

Postby cobretti » March 11th, 2016, 1:28 pm

I tested a regular LCD to see if that will make any difference with popping noise, but it didn't. The nasty switching square wave on power rails is gone of course, but no cigar. I verified the 5VDC with my scope and I don't see any glitches or any other problems. I found out that one mini USB cable was for some reason shorting the mini USB connector shell to chassis after plugged in the laptop. Go figure. I threw that USB cable away. Some cheap Chinese garbage anyway......
When checked with my multimeter, I have exactly 1Mohm between mini USB and chassis (LCDuino negative rail). New USB cable is now OK. I still have the popping noise when turned ON and switching between inputs. What else can I check?
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Re: γ3 On the Move

Postby amb » March 11th, 2016, 1:38 pm

Disconnect all inputs and outputs and check to make sure the IG and G portions of the ground plane are isolated from each other (measure resistance).
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Re: γ3 On the Move

Postby cobretti » March 12th, 2016, 5:56 am

It is open circuit, no resistance there.
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Re: γ3 On the Move

Postby cobretti » March 12th, 2016, 6:02 am

I checked everything. All voltages are there. No shorts or suspicious resistances. Clock is exactly as supposed to be, Z1 as well. Passed all the checklist. I start to suspect that SRC chip my be damaged.
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