[K3cT]

OK, I thought γ2 needs external power to perform its best and since my γ1 Lite is USB bus-powered, I'm thinking of populating the parts required for that at γ1 DAC board.

 

[amb]

A good/clean linear regulated external supply should be better than USB power, but the difference is not night and day. My measurements show that USB power causes some minor noise floor spikes/hash, whereas it's absolutely clean and spike-free running on a σ25 PSU (or a CUI 5VDC linear regulated wallwart I have on hand that's no longer available). If you'd like a little overkill, you could also use a σ11 and know that the PSU will never be a performance bottleneck.

Of course, different computers may have different levels of USB power noise, so one can't really conclude that USB power will always be audibly worse.

 

[K3cT]

Quote:

Originally Posted by amb /img/forum/go_quote.gif A good/clean linear regulated external supply should be better than USB power, but the difference is not night and day. My measurements show that USB power causes some minor noise floor spikes/hash, whereas it's absolutely clean and spike-free running on a σ25 PSU (or a CUI 5VDC linear regulated wallwart I have on hand that's no longer available). If you'd like a little overkill, you could also use a σ11 and know that the PSU will never be a performance bottleneck. Of course, different computers may have different levels of USB power noise, so one can't really conclude that USB power will always be audibly worse.

Gotcha. I guess why not since any improvement is good in my book.

I've studied the schematics and documentations in the γ1 site. These locations ie. J1D, L4D, C1D, U1D, R14D, R15D, R16D, and U1D (I don't have the U1D installed) are all that are required to be populated for the external 5V DC PS no? Please correct me if I'm wrong somewhere.

That should be all that are required to prep the γ1 for γ2 conversion am I correct? JP1U is empty in my γ1 so that shouldn't be a problem.

Thanks, ti.

 

[amb]

Quote:

Originally Posted by K3cT /img/forum/go_quote.gif I've studied the schematics and documentations in the γ1 site. These locations ie. J1D, L4D, C1D, U1D, R14D, R15D, R16D, and U1D (I don't have the U1D installed) are all that are required to be populated for the external 5V DC PS no?

Correct.

Quote:

That should be all that are required to prep the γ1 for γ2 conversion am I correct? JP1U is empty in my γ1 so that shouldn't be a problem.

You should have a wire shunt across JP1U pins 2-3 if you have a γ1 Lite (B) configuration. This selects I2S output from the PCM2707. JP1D should also be shorted with a jumper.

 

[PScal]

Quote:

Originally Posted by PScal /img/forum/go_quote.gif I could use some troubleshooting help. I finished the gamma 1 and gamma 2 (yay!) and the initial tests passed. The gamma 1 works, but when I plug in the gamma 2, it does not work. I get an 'unrecognized usb device' error on the PC. I noticed that the 4.5v and 3.3v test points were measuring equal voltages when powered on (about 2.5 volts) despite reading a large ohm value when powered off. I also measured resistance when powered on and it seems they are shorted (<1 ohm resistance)... but as soon as I unplug it, the resistance goes up (5k ohm and greater). Has anyone experienced this before? Edit. it appears I do have a short. The 3.3v and 4.5v are continuous with ground even when disconnected. The hunt begins...

So, weird stuff is happening over here. I noticed that the 3.3v and 4.5v are only shorted after the gamma 2 has been plugged in. First thing when I plug it in, everything works. Then after a couple seconds, the voltages go crazy. My multimeter shows this, and the LED switch also comes on rock solid (red, green, red), then starts to flicker (red) after a 2-ish seconds.

After I unplug the USB, the 3.3v and 4.5v are continuous for a few minutes on the gamma 2 board. Over time, the resistance between them increases. I assumed the problem was with the DAC, as it seems to be the only thing that touches both 3.3v and 4.5v, but I can't figure out why the resistance seems to be changing over time. Any advice on this?

PS - the gamma 1 sounds very nice

 

[MisterX]

Quote:

I also measured resistance when powered on and it seems they are shorted (<1 ohm resistance)... but as soon as I unplug it, the resistance goes up (5k ohm and greater).

You cannot measure resistance when the circuit is powered on.

How to Measure Resistance with a Multimeter :: Electronics and Radio Today

Quote:

Remember to ensure the circuit under test is not powered on. Under some circumstances it is necessary to measure resistance values actually on a circuit. When doing this it is very important to ensure the circuit is not powered on. Not only will any current flowing in the circuit invalidate any readings, but should the voltage be high enough, the current resulting could damage the multimeter.

Quote:

I can't figure out why the resistance seems to be changing over time.

You're charging the capacitors.

Quote:

Ensure capacitors in a circuit under test are discharged. Again when measuring resistance values in a circuit, it is necessary to ensure that any capacitors in the circuit are discharged. Any current that flows as a result of them will cause the meter reading to be altered. Also any capacitors in the circuit that are discharged may charge up as a result of the current from the multimeter and as a result it may take a short while for the reading to settle.

 

[ShinyFalcon]

Try looking at WM8741's pins 8 and 9, if those are bridged then it will short 3.3V and 4.5V. Heat may cause whatever bridge there is to expand, shorting those two. See if these two voltage points are shorted to ground as well, they shouldn't be.

 

[PScal]

Thanks for the information. I will continue troubleshooting

 

[PScal]

Well still no luck. I am certain pins 8 and 9 are not bridged (via multimeter). The circuit seems to be stable for a few seconds (until the caps charge is my guess) then the voltages plummet. Here's a picture of my board... including melted plastic film cap. Any sore thumbs sticking out?

 

[mattcalf]

If I'm using Cardas Quadeutectic (activated rosin core flux) on my Gamma1+2 should I wait until I have flux or will I be fine soldering with it?

 

[PScal]

Quote:

Originally Posted by PScal /img/forum/go_quote.gif Well still no luck. I am certain pins 8 and 9 are not bridged (via multimeter). The circuit seems to be stable for a few seconds (until the caps charge is my guess) then the voltages plummet. Here's a picture of my board... including melted plastic film cap. Any sore thumbs sticking out?

Scratch that... cleaned off a little flux from between the pins and she's singing now. Yeah!

 

[MisterX]

Quote:

If I'm using Cardas Quadeutectic (activated rosin core flux) on my Gamma1+2 should I wait until I have flux or will I be fine soldering with it?

I would suggest waiting.
It makes it all a lot lot lot lot more easier when you have flux for the SMDs.

Quote:

Scratch that... cleaned off a little flux from between the pins and she's singing now.

Pins 13 and 14 of U4 by chance?
They look pretty close in the picture and it fits the symptoms you had described.
Nice assembly job.

 

[mattcalf]

Quote:

Originally Posted by MisterX /img/forum/go_quote.gif I would suggest waiting. It makes it all a lot lot lot lot more easier when you have flux for the SMDs.

Ok thanks for that.

Damn DealExtreme, they need to get their sh!t together.

 

[Beefy]

Quote:

Originally Posted by mattcalf /img/forum/go_quote.gif Damn DealExtreme, they need to get their sh!t together.

You really need to stop looking to the internet, when a trip to your local store is so much easier...... Solder Flux Pen 12ml - Jaycar Electronics

I built two y1's with this pen, and it works perfectly.

 

[mattcalf]

Thanks beefy, I thought I had already searched the Jaycar site for such a solution, however, on second glance I only searched for 'flux remover'.

Should've known better, Jaycar hasn't disappointed so far.

Cheers,
Matt.