Hi all, meant to post in here a while ago. I build an O2 amp/DAC earlier this year. I wanted to add RCA line outs on the back, as well as move the power plug back there, but couldn't find any faceplates for sale or designs that accomodated this. I ended up designing my own in SolidWorks, and having them cut on a CNC machine. The machinist ended up following the path for the text rather than cutting it the way I had drawn up, but it still turned out well. If anyone is interested I can supply the files - SolidWorks is able to save in a variety of formats.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hello,
I have just built my own O2 DAC from the kit and am having a few problems.
I have run through the trouble shooting guide and didnt manage to solve the problem, I have also searched this extensive thread and not come across a similar problem.
The problem I am getting is that I am reading 11.06V on both the left and right channels of the 6.35mm output jack.
I think I have traced the problem to U3 and U4 because the they seem to be outputting the 11.06V when the input on pins 3 and 5 are only 1.36V.
Any suggestions are welcomed,
Thanks, Michael
I have just built my own O2 DAC from the kit and am having a few problems.
I have run through the trouble shooting guide and didnt manage to solve the problem, I have also searched this extensive thread and not come across a similar problem.
The problem I am getting is that I am reading 11.06V on both the left and right channels of the 6.35mm output jack.
I think I have traced the problem to U3 and U4 because the they seem to be outputting the 11.06V when the input on pins 3 and 5 are only 1.36V.
Any suggestions are welcomed,
Thanks, Michael
Wow, that must have been the one thing I didnt check.
My negative rail is reading +2.51V!
Looks like this could be the source of the problem, I think I am now going to check for shorts because that is not only a long way out but the inverse to what it should be.
Than you so much.
Michael
My negative rail is reading +2.51V!
Looks like this could be the source of the problem, I think I am now going to check for shorts because that is not only a long way out but the inverse to what it should be.
Than you so much.
Michael
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Well its a strange fault, I have just double checked the fault I was having and there more to the story...
Originally I got to the step that said
"Apply AC power and ensuring S1 is still ON measure the DC voltages at pins 8 and pins 4 of the remaining empty IC sockets"
And I was getting +2.51V
I just sat down again to check that that was the case and I got -11.30V on the negative rail. But then upon watching the meter I watched it slowly tick towards 0.
Now in the time it took me to write this I have powered it back up, with just U2 fitted still, and read +4.22V dropping towards 0 slowly on the negative rail.
Pin 4 of U2 is at a stable -11.90V
Maybe a capacitor problem??
Thanks,
Michael
Originally I got to the step that said
"Apply AC power and ensuring S1 is still ON measure the DC voltages at pins 8 and pins 4 of the remaining empty IC sockets"
And I was getting +2.51V
I just sat down again to check that that was the case and I got -11.30V on the negative rail. But then upon watching the meter I watched it slowly tick towards 0.
Now in the time it took me to write this I have powered it back up, with just U2 fitted still, and read +4.22V dropping towards 0 slowly on the negative rail.
Pin 4 of U2 is at a stable -11.90V
Maybe a capacitor problem??
Thanks,
Michael
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You need to carefully recheck your results. Make sure that the black lead of the meter is always firmly connected to ground. Any flux or lacquer present on the board can 'insulate' the meter probes so always be sure you have a good connection.
We are aiming for PLUS 12 volts on pin 8 and MINUS 12 on pin 4 of U2. Until you are certain that is present we can't go further.
(12 is a nominal figure... anything from 11.5 to 12.5 is within spec)
If the voltage isn't present on U2 then you trace back to the output of the two regulators and see if the voltage is there.
If one or both are missing then you look at the input to the regulators and ensure that you have at least 15 or more volts present, plus 15 for the upper reg and minus 15 for the lower.
I'm out of time for today
so work through it slowly and follow the guide as that is carefully written and should lead you to the problem area.
We are aiming for PLUS 12 volts on pin 8 and MINUS 12 on pin 4 of U2. Until you are certain that is present we can't go further.
(12 is a nominal figure... anything from 11.5 to 12.5 is within spec)
If the voltage isn't present on U2 then you trace back to the output of the two regulators and see if the voltage is there.
If one or both are missing then you look at the input to the regulators and ensure that you have at least 15 or more volts present, plus 15 for the upper reg and minus 15 for the lower.
I'm out of time for today
so work through it slowly and follow the guide as that is carefully written and should lead you to the problem area.
Just a quick thought as I may be misunderstanding you.
If you mean the plus and minus 12 volts is OK on U2 then you can safely link out (with a bit of wire) both FET's such that pin 8 of U2 connect to pin 8 of all the other opamps and pin 4 of U2 connects to pin 4 of all the other opamps.
That would bypass the FET switches and U2 and allow you test the amp works OK.
If you mean the plus and minus 12 volts is OK on U2 then you can safely link out (with a bit of wire) both FET's such that pin 8 of U2 connect to pin 8 of all the other opamps and pin 4 of U2 connects to pin 4 of all the other opamps.
That would bypass the FET switches and U2 and allow you test the amp works OK.
Yes I think there was some misunderstanding there, my fault for not being very clear!
Anyways I tried the idea your idea of manually connecting all pin 4's together and all the pin 8's together and it worked!
For the first time since I built this amp it is working!
I cant thank you enough man, i think the next step I will take is replacing the FET's and see if that cures the problem.
Have a great night, and thank you again!
Michael
Anyways I tried the idea your idea of manually connecting all pin 4's together and all the pin 8's together and it worked!
For the first time since I built this amp it is working!
I cant thank you enough man, i think the next step I will take is replacing the FET's and see if that cures the problem.
Have a great night, and thank you again!
Michael
Pin 1 is correct, pin 7 is not.
Hmmm... reading voltages around comparators can be a little tricky because the meter can sometimes influence readings but on the face of it pins 5 and 6 (the inputs to the second comparator) look OK.
Lets just think about that......
Pin 5 is actually higher in voltage (less negative) than pin 6 and so that should swing the comparator output high. So is the problem the comparator (or something around it) or is the FET faulty and over-riding the voltage on pin 7.
If you could remove Q2 then the voltage on pin 7 should come up to PLUS 12 volts. If it does, then the FET is the problem. If it doesn't then there is a problem around the comparator.
Another method that might work and involves no desoldering would be to remove U2, and then to carefully refit it with pin 7 gently bent out of the way. No need to push the IC fully home in the socket, just as long as the pins are making contact.
Hmmm... reading voltages around comparators can be a little tricky because the meter can sometimes influence readings but on the face of it pins 5 and 6 (the inputs to the second comparator) look OK.
Lets just think about that......
Pin 5 is actually higher in voltage (less negative) than pin 6 and so that should swing the comparator output high. So is the problem the comparator (or something around it) or is the FET faulty and over-riding the voltage on pin 7.
If you could remove Q2 then the voltage on pin 7 should come up to PLUS 12 volts. If it does, then the FET is the problem. If it doesn't then there is a problem around the comparator.
Another method that might work and involves no desoldering would be to remove U2, and then to carefully refit it with pin 7 gently bent out of the way. No need to push the IC fully home in the socket, just as long as the pins are making contact.