[Wood]

Yes I asked the same a while back. qusp argues that .1uf bypass is necessary.

http://www.head-fi.org/forums/f7/val...ml#post6302565

Got me thinking it might be worth while replacing the .1uf bypass with something better, and then adding, in addition, say a .01uf bypass cap as well, triple bypass so to speak.

 

[MikeW]

I put a 10uf silmic 2 across the + and ground coming off the voltage regulator in the DC30, for the +5v rail. Now there was no measured DC coming out of the DC30, but for some reason when you put the 10uf cap in line it changed the +5 out to +5.35 and it would not go lower. I tried putting a 01. uf film cap across and it did not effect the voltage much, but it did not remove the AC! crap

I wonder if this has a similiar effect in the dac on the power reserve mod, are those caps increasing the voltage going to the board?

 

[Wood]

Mike, perhaps you could try powering the Chamelon, with the Valab 3 power supply, rig up 3 wires, to test if you still get hiss. It might at least eliminate some factors. I am assuming of course your not getting hiss with your Valab 3. So if you still get hiss then it might indicate the problem lies elswhere and not with the DC-30.

 

[driguy]

Mike, you got rid of your A/C problem. Be happy! Did you HEAR any difference? I measured mine and did not have ANY A/C whatsoever but that is neither here nor there. Be sure you are measuring the 5 volt rail after the cap. If it is still above 5 volts then just lower it with the variable resistor and you are done. No need to go into the theory as to why it is measuring higher. Still, very odd that you had A/C after one regulator and not the other.

 

[MikeW]

i can not lower it enough, and i can't plug it in while it's 5.5+ volts on that rail it might fry somthing. I don't have a lower cap value to try. that's not a bad idea wood, but it's a pain in the ass for sure.

 

[Wood]

Yes its a hassle, last resort stuff, but just to test of course, but hey, then again, your pretty fast with the iron I noticed.

 

[driguy]

Hi Pat,
I noticed that you still have the stranded wire on the SPDIF input. If you have any decent single strand wire you will probably see a nice sound increase by getting rid of the stranded stuff especially but not limited to the high frequency digital signal. Silver is best but even nice copper (even 28 gauge is fine) will work fine there. Of course, both signal and ground will have to be changed. At least it is only a couple of inches! I will be curious to see if you notice the change.

Tony

 

[Bill Allen]

Pretty funny how you guys a have to simplify what I'm rambling on about. Team effort, thanks! I know sometimes I get sounding like a cryptic audio review from Srajan of 6 Moons.

Pat-perfect picture showing the floating Spdif input mod and factory installed green .1uf cap. Steve Nugent reports a .1uf Wima radial film cap will work just fine here at ultra low cost. I will suggest TeraDak do this at the factory and save everyone the drama.

Like Qusp mentioned a couple pages back you have to be careful about digital signal integrity when you go messing with the surface mount caps and resistors in the digital path. IMO most of these bits are best left to the experts as you can do more harm then good.

Tony reports that his Chameleon DC-30 came with the yellow wire factory attached and that its only warm to the touch. They must have changed the value of the resistors to the voltage regulator to make it run cooler. Maybe the new wiring diagram will reveal something for those of us still running hot.

Speaking of hot, if Wood's Chameleon DAC gets sounding any better he may experience SHC (Spontaneous Human Combustion). Not good!

 

[Wood]

No worries I've already prepared the BCW mod 'bucket of cold water'

 

[Bill Allen]

Good call on the BCW Woody.

For the rest of you who have your Chameleon DAC hitting on all cylinders may I suggest you march down a buy a big supply of Depends. We don't want any inadvertent bowel movements. (IBM's)

Safety First!

 

[driguy]

Mike, am I correct by inferring from your last posts that you are measuring your 5 volt rail without it hooked up to a load? That is a Bozo No No. Without a load you will get incorrect readings. There is no place for the current/voltage to drain. The regulator needs this to work properly. If you did this you charged up the capacitor and that is why you have too much voltage. Drain the cap (short the leads) or disconnect it altogether. Connect the power supply to the DAC. Then set your voltage to 5 volts again. I do not think that 5.5 volts will hurt anything. The receiver chip voltage is supplied by the 3.3 volt regulator and the other chip is good up to 7 volts according to the PDF I looked up.
Now that you have the voltage set correctly again, measure the voltage at the DAC card, not at the DC-30. If you are still getting A/C then try installing the cap on the DAC board where it comes in after the 3 pin connector. One leg to the 5 volt pin and the other to ground.
Also, please remember that the receiver is being fed by another regulator which has some more power supply rejection rate so that little bit of A/C is probably not getting through to that chip. If you would please measure the positive voltage going into the receiver card (do not remove the card). Just use the pins there. Also, can you measure the 5 volt supply going to the DAC chip board? It is labeled there with the four pins going to that sub board. I am curious as to whether you have any A/C at those points.
Tony

 

[MikeW]

Here's some new pics of lattest mods. I don't know if I did that power supply cap properly. Maybe someone can take a look at it.

Once i installed it this way, the voltage is a solid +5v dc out, and there is 0.003 ac in it now, down from 0.036 ac.

Unfortunatly it does not seem to effect the noise. Which im probably exagerating anyways. For example if any song has it's own noise floor at all, it completely drowns out the dac. I can't really hear it at all at normal/loud volume levels with music playing.

 

[MikeW]

yeah i been measuring without load, I just powered everything up and took the measurments like you said.

from the main PCB +5 v to the Dac board there is 0.003 ac going into the dac board, from the pin that comes from the main pcb to the digital input board, where they are connected +5v there is 0.003ac going into the digital input board.

From the IEC inlet, there is 0.003ac. There is no ac detected on any of the +7.5 volts.

That's interesting what you said about the output voltage with that cap, I had it wired up differently earlier, it was wired directly to the voltage regulator + and ground and that is where I had 0 AC, but I was afraid to try it with the high output voltage reading.

It also looks like my +5v is a little low @ 4.93 volts under load. My +7.5 also dropped from 8.86 to 8.23 under load.

 

[PatOMalley]

Quote:

Originally Posted by driguy /img/forum/go_quote.gif Hi Pat, I noticed that you still have the stranded wire on the SPDIF input. If you have any decent single strand wire you will probably see a nice sound increase by getting rid of the stranded stuff especially but not limited to the high frequency digital signal. Silver is best but even nice copper (even 28 gauge is fine) will work fine there. Of course, both signal and ground will have to be changed. At least it is only a couple of inches! I will be curious to see if you notice the change. Tony

Tony, Refresh your page because I put a new pic up showing silver for both pos and neg coming off the coax input. That wire is 6n soft annealed silver. Nice and easy to work with in that location as the board will have to come out a couple more time and the wire is less than stiff.

 

[PatOMalley]

Quote:

Originally Posted by Wood /img/forum/go_quote.gif Yes I asked the same a while back. qusp argues that .1uf bypass is necessary. http://www.head-fi.org/forums/f7/val...ml#post6302565 Got me thinking it might be worth while replacing the .1uf bypass with something better, and then adding, in addition, say a .01uf bypass cap as well, triple bypass so to speak.

Triple bypass? Ya think? I am not so sure removing them is the wrong thing to do. You usually bypass a poor cap with a better cap but in this case that is reversed. If you use a good capo then you do not need a bypass. Hmmm. Maybe bipolar is the way to go and remove the bypasses? Nichicon has 'em.