I'm using the O2 for a week now with some Senn's HD 650's, and I have to say they're quite the pair. Great stuff...
Nice picture....of your thumb
WWell I thought I'd share my list of Objective 2's that I built thus far. My favorite is still the clear one.
1st. Silver All Around
2nd. B3 Case in Gold
3rd. Clear Front with Black Case
The last few pictures are of the Remote Mount I did for the AC Adapter port. The guy who wants this amp asked me if I could do that and sure enough I did it. Still doesn't make much sense why it was front mounted in the first place, but I guess it's because of how the board is layed out. It really doesn't bother me though, it's nice having everything in one place.
1st. Silver All Around
2nd. B3 Case in Gold
3rd. Clear Front with Black Case
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The last few pictures are of the Remote Mount I did for the AC Adapter port. The guy who wants this amp asked me if I could do that and sure enough I did it. Still doesn't make much sense why it was front mounted in the first place, but I guess it's because of how the board is layed out. It really doesn't bother me though, it's nice having everything in one place.
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Just received my O2 from JDS Labs.. very pleased otherwise, but I'd have happily paid for better jacks 
- Kenwood KH-K1000 are very tight fit on the headphone jack, DT-770 is somewhat ok..
- I can't get my Cordial 3.5mm interconnect out of the input jack, I can move it slightly then something just stops it, even tried moderate force. Oh well, it's not like I need to remove it anyway.
edit: Heh, now I got my interconnect out.. needed very good wiggle up and down.
- Kenwood KH-K1000 are very tight fit on the headphone jack, DT-770 is somewhat ok..
- I can't get my Cordial 3.5mm interconnect out of the input jack, I can move it slightly then something just stops it, even tried moderate force. Oh well, it's not like I need to remove it anyway.
edit: Heh, now I got my interconnect out.. needed very good wiggle up and down.
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Yes they are the blue ones.. might be a bad batch or whatever. Too much hassle to send it back. Maybe I'll change them someday for the real diy experience.
Time for my "odd" question. My O2 came with the Triad 12VAC 200mA power supply. Obviously, most of the wall warts sold are of the "DC" variety. However, mine has died quite recently and I'm interested if anyone - in the U.S. has found a local vendor that might carry such a part? I don't even care which end it has on it since I can solder the correct on on from the Triad supply.
I do realize my 2nd option is to do an Internet order to get the Triad replacment wall wart. I was just looking at saving some time and thought I'd ask if anyone has done the same with a local shop?
I've tried Radio Shack, Batteries Plus, etc. Nothing seems to be in stock or stocked at those areas except for the DC output adapters.
Thank you,
I do realize my 2nd option is to do an Internet order to get the Triad replacment wall wart. I was just looking at saving some time and thought I'd ask if anyone has done the same with a local shop?
I've tried Radio Shack, Batteries Plus, etc. Nothing seems to be in stock or stocked at those areas except for the DC output adapters.
Thank you,
Hey guys,
So I've failed with my O2 build attempt... Another noob looking for help from the pros.
The resistances seem to check out, but when I connect the AC U6 quickly becomes too hot to touch. When I was building I was rushed towards the end and messed up with Q2 - I made a solder bridge. Up until then I had been very careful about grounding myself and not touching the pins. Can an overheating U6 be a sign of Mosfet failure?
I don't know what the next step should be - with U6 overheating I don't feel ok about leaving the plug in to check voltages. Should I attach a bigger heatsink to it for testing?
I may be able to get new regulators or mosfets from a local electronic store (Conrad in Frankfurt), though they probably won't be the same brands...
I'm also concerned about whether I could have damaged Q1,2 or U5,6 with too much heat. I had my soldering iron above 350 degrees C because I was trying to make quick connections, but my solder wire is pretty thin and I think that I heated for too long while feeding the joints.
Should I link to pictures of my PCB or something like that?
aiyaiyai...
So I've failed with my O2 build attempt... Another noob looking for help from the pros.
The resistances seem to check out, but when I connect the AC U6 quickly becomes too hot to touch. When I was building I was rushed towards the end and messed up with Q2 - I made a solder bridge. Up until then I had been very careful about grounding myself and not touching the pins. Can an overheating U6 be a sign of Mosfet failure?
I don't know what the next step should be - with U6 overheating I don't feel ok about leaving the plug in to check voltages. Should I attach a bigger heatsink to it for testing?
I may be able to get new regulators or mosfets from a local electronic store (Conrad in Frankfurt), though they probably won't be the same brands...
I'm also concerned about whether I could have damaged Q1,2 or U5,6 with too much heat. I had my soldering iron above 350 degrees C because I was trying to make quick connections, but my solder wire is pretty thin and I think that I heated for too long while feeding the joints.
Should I link to pictures of my PCB or something like that?
aiyaiyai...
Remove the batteries, if there are any, turn the O2 power switch "off" (out), then plug the AC adaptor in and see if U6 is still heating up.
With the power switch "off" the O2 power supply is still on but not hooked to the mosfets and the rest of the amp. If U6 heats up with the power switch off you have a power supply short, otherwise the short is in the rest of the amp.
Wow, thanks for the rapid tech support. The little guy is here mocking me.
U6 is heating up with the power switch in the 'off' position. Scolding hot, very quickly. I had a 'what the hell' moment and quickly plugged the cord in to measure V over the battery slots.
B1 gives 11.9 V, B2 gives 0, as far as I can tell. I didn't want to leave the plug in long.
Need to run to pick up dinner, but will be watching keenly for things to try.
P.S. Adapter is one I found in my dad's shed. From a light I think. I can write down the specs shortly.
Yeah, that is the first most important thing. Needs to have AC output, not DC like most adaptors.
If the adaptor is OK and in the range of 12VAC - 20VAC then work through the steps I posted starting with post #1855 in this thread. That was for a fellow having the same issue as you but with a dead positive supply instead of the dead negative. For the negative supply you would look at D4, C3, C5, U6, C7, D5 and R2 instead.
Also read through this thread helping another fellow debug an O2 power supply. A boatload of good troubleshooting info in there.
http://www.diyaudio.com/forums/headphone-systems/204736-my-objective-2-will-not-turn.html
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Yeah, that is the first most important thing. Needs to have AC output, not DC like most adaptors.
If the adaptor is OK and in the range of 12VAC - 20VAC then work through the steps I posted starting with post #1855 in this thread. That was for a fellow having the same issue as you but with a dead positive supply instead of the dead negative. For the negative supply you would look at D4, C3, C5, U6, C7, D5 and R2 instead.
Also read through this thread helping another fellow debug an O2 power supply. A boatload of good troubleshooting info in there.
http://www.diyaudio.com/forums/headphone-systems/204736-my-objective-2-will-not-turn.html
Thanks for the links. The supply is
Input: 230-240V-50HZ
Output: 12V Max 12VA
So it is AC. It gives only 12.8 VA, though, so I know I need a better one. I thought I could use it to test the circuit. I'm looking intently for shorts but can't find one at the moment. Maybe I just killed U6.
If I link to some pics would you be willing to be critical of my joints?
Unfortunately solder bridges wouldn't show up well in a photo. Best thing to do is use a magnifying glass and take a look at them directly. Especially the solder joints on U6 - it is very hard to see a bridge between those pins without the magnifier.
You should get -24.9V or so to ground (metal shell of the gain switch) at the non-banded side of D4, going into the regulator.
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