You probably know already, but don't turn on the power button until you have this ps issue resolved.
I'm not seeing anything wrong with your parts installation. Except for Q1 and Q2, which shouldn't have an effect on the regulator circuit. My Q1 PQU17P06 is the DPAK package and Q2 PQPF10N20 is the insulated TO220. Q1 is nearest the regulators and Q2 is nearest the batteries. Yours seems backwards, but you may have sourced different parts. Worth a quick check.
What voltage do you read between the cathode of D3 and the anode of D4? It kinda seems like you're only getting halfwave power. The reading should be around 32 volts with your transformer.
I'm not seeing anything wrong with your parts installation. Except for Q1 and Q2, which shouldn't have an effect on the regulator circuit. My Q1 PQU17P06 is the DPAK package and Q2 PQPF10N20 is the insulated TO220. Q1 is nearest the regulators and Q2 is nearest the batteries. Yours seems backwards, but you may have sourced different parts. Worth a quick check.
What voltage do you read between the cathode of D3 and the anode of D4? It kinda seems like you're only getting halfwave power. The reading should be around 32 volts with your transformer.
Cheers guys, will try taking the regs out as a first step.
Cathode D3 measured 16.9V wrt gnd. Anode D4 was -16.9V wrt gnd when I measured them earlier. Which is in the ballpark you indicated and lines up with range indicated by RS in this drawing.
Edit: Just got the first one out. Had the 7812 in U6, that confirms that part of the puzzle!
Cathode D3 measured 16.9V wrt gnd. Anode D4 was -16.9V wrt gnd when I measured them earlier. Which is in the ballpark you indicated and lines up with range indicated by RS in this drawing.
Edit: Just got the first one out. Had the 7812 in U6, that confirms that part of the puzzle!
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@hochopeper...
As sofaspud wrote, check the regs before you solder them back again so that you get the right one at the right position. There are pictures earlier in this thread as there are in RS (nwavguys) blog. So if you have bought parts according to the BOM you could use the pictures to get them right.
Brgds
As sofaspud wrote, check the regs before you solder them back again so that you get the right one at the right position. There are pictures earlier in this thread as there are in RS (nwavguys) blog. So if you have bought parts according to the BOM you could use the pictures to get them right.
Brgds
Glad the problem got tracked down. I suggest temporarily soldering some small wires from the PCB regulator input and ground to the respective regulator leads while they are off the board, then measuring the output pin to make sure you get + and - 12 volts. Just to verify they are still functional before permanently replacing them on the board. Please check those FETs too while the iron is hot.
Certainly not as glad as I am! Regulator voltages all check out now.
Thanks for mentioning the FETs too! They did need swapping. But ...
I think Q2 may have not enjoyed the relocation. Have checked the voltages quickly already but I'll try again tomorrow to get to bottom of those. All of the voltages related to Q1 seem ok.
Lesson learned for trying to whip it up in a hurry late last night though!
@hochopeper, I'm glad you found your regulator problem. Be sure to carefully run the power controller tests (removing each battery and following the instructions) to make sure Q1 and Q2 are working correctly.
@fourier, I have not revised the gerber files. The only changes since August have been to the parts list, not the PCB board. The only change I've considered making is to move the via away from the corner of the gain switch. But it doesn't seem to be a problem for the majority of O2 builders and is easily fixed if it is.
@fourier, I have not revised the gerber files. The only changes since August have been to the parts list, not the PCB board. The only change I've considered making is to move the via away from the corner of the gain switch. But it doesn't seem to be a problem for the majority of O2 builders and is easily fixed if it is.
Having a little trouble with my second build. I'm getting nothing for the initial supply voltage test using the wall adapter and measuring across the battery terminals. All I get is a rapidly descending mV reading. I tried re-flowing the power terminals, but that did nothing. I know the voltage regulators are in correctly, although I could try and re-flow those connections as well. Any ideas where I should start?
@shadow, it sounds like perhaps your DMM is set for AC voltage (rather than DC), you're not connecting one probe to a proper ground, there's a short on the board between the power jack and the regulators, or your wall transformer is toast.
Measure, with the DMM set for AC, the voltage at the wall adapter plug (without it even plugged into the O2). It should be 13.5 volts AC or more. If it's zero you found your problem. If that's OK, plug it into the O2, switch your DMM to DC, and measure at the diodes near the power jack as shown in the diagrams on the blog. You can also measure across any of the 4 big power supply capacitors. Each should be 16+ volts DC.
Measure, with the DMM set for AC, the voltage at the wall adapter plug (without it even plugged into the O2). It should be 13.5 volts AC or more. If it's zero you found your problem. If that's OK, plug it into the O2, switch your DMM to DC, and measure at the diodes near the power jack as shown in the diagrams on the blog. You can also measure across any of the 4 big power supply capacitors. Each should be 16+ volts DC.
It was set to DC, but of course it's easy an easy mistake to make. The wall plug measures 13.5V AC wasn't sure if I should leave it connected since initial test says to unplug if you're not getting 24V across battery terminals. Will proceed with raw voltage tests and report. I did find a small solder bridge whisker, which I fixed, between the center pin of U5 and the film cap next to it. Not sure if that would have screwed things over, but fixing it hasn't helped. back in a bit...
I think Q1 is toast. Just getting a descending mV reading with the pos lead at r24 and neg lead at both battery grounds. I'll try to re-flow first, but I have a spare Q1. If I never intend to use batteries in this build would it matter if I don't replace Q1?
Every thing else measures correctly by the way
Every thing else measures correctly by the way
It lives!
All tests completed fine, sacrificial headphones survived. Now with AD900 making some sweet sounds.
Thanks to RS for the design and all your efforts with the VERY detail docs!! Thanks to Turbon and Sofaspud for pointing out where I went wrong too.
Kinda feel like an id10t. Everything was working fine except me. For some reason the battery terminal pad on the far right of BT2 would not read any voltage or resistance measurements. Once I switched to the center pad all was well. Glad I went over it with a fine tooth comb though. Discovered one of the leads for the remote volume had a shoddy joint. Kind of a pain if I had discovered that after I had boxed it up. All has ended well. 
Good you found it shadow419! But anyway it's just 4 screws away...
I'll copy that greenalien - I too want to take the opportunity to wish RocketScientist and all those involved with setting up and operating the various group buys a Very Merry Christmas! I'm sure about that the ODA+ODAC will be a similar success story!
Merry Christmas!
I'll copy that greenalien - I too want to take the opportunity to wish RocketScientist and all those involved with setting up and operating the various group buys a Very Merry Christmas! I'm sure about that the ODA+ODAC will be a similar success story!
Merry Christmas!
@All, thanks for the holiday wishes and kind words.
@Alexium, it depends on the signal level and the O2's gain. Offset at the input to the O2 shifts the center point of the gain stage's output by the amount of Voffset * GAIN. So with 2.5X gain, +50 mV of input offset becomes +125 mV at the 2062's output. That means it will clip 0.125 volts sooner (asymmetrically) on the positive side of the waveform. In practice, that's unlikely to be a problem. But if you apply 2 volt of DC to the input, it will clip 5 volts sooner cutting the total maximum output in half (20 Vp-p becomes 10 Vp-p).
If it's a problem, just add some high quality 2.2 uf - 10 uF film caps (MKP, MKT, etc.) at the input. Contrary to popular belief, the right caps won't degrade the sound.
@Alexium, it depends on the signal level and the O2's gain. Offset at the input to the O2 shifts the center point of the gain stage's output by the amount of Voffset * GAIN. So with 2.5X gain, +50 mV of input offset becomes +125 mV at the 2062's output. That means it will clip 0.125 volts sooner (asymmetrically) on the positive side of the waveform. In practice, that's unlikely to be a problem. But if you apply 2 volt of DC to the input, it will clip 5 volts sooner cutting the total maximum output in half (20 Vp-p becomes 10 Vp-p).
If it's a problem, just add some high quality 2.2 uf - 10 uF film caps (MKP, MKT, etc.) at the input. Contrary to popular belief, the right caps won't degrade the sound.
Has this claim some empirical support or is it merely the regurgitation of a popularly held belief?