Just use solder braid (sometimes called solder wick) to pull the solder out of the hole. I believe Radio Shack even still sells it.
For best results, make sure your tip is hot (bump up the heat if it's adjustable), and brush some liquid flux onto the braid before you begin. Then just push the fluxed part of the braid against the hole and heat it with the soldering iron.
If you don't want to go to all that trouble, solder drills out pretty easily. Just make sure you secure the board (a Panavise or similar works best), use a tip smaller than the hole, and center it (you don't want to damage any through-hole plating).
P.S.: Give yourself plenty of wick between the hole and your fingers. An annoying property of copper is that it conducts heat rather more quickly than you might expect in this situation.
ericj - another thought about your O2. If the power supply is measuring OK with the power switch off, the easiest thing to do would probably be just change out all 4 op amps as a set. If you order them might as well get a set of mosfets too, just in case, since it is all fairly cheap.
That would save a bunch of debugging time and may eliminate a failure down the road if the unbalanced rails caused any lingering problems.
Good luck!
That would save a bunch of debugging time and may eliminate a failure down the road if the unbalanced rails caused any lingering problems.
Good luck!
ericj - another thought about your O2. If the power supply is measuring OK with the power switch off, the easiest thing to do would probably be just change out all 4 op amps as a set. If you order them might as well get a set of mosfets too, just in case, since it is all fairly cheap.
That would save a bunch of debugging time and may eliminate a failure down the road if the unbalanced rails caused any lingering problems.
Good luck!
Thanks. I had bigger fish to fry over the weekend and didn't get to my O2.
The 4556 and 2068 are some of my favorite chips so i may have spares anyway. Perhaps today i should go ahead and order new mosfets and regulators, just in case.
You can also get what is known as a 'solder sucker' at Radio Shack. It is manual operation which is cheap and fast and gets all the solder out of the hole. Other places sell an ac powered Solder Sucker... which is what I use now. -Thx RNMarsh
I am also a fan of copper braid solder wick that has been liberally coated with good flux.
Sometimes you have to add a big blob of solder to a through-hole in order to suck it clean, btw, regardless of technique.
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Hi guys, thanks for the suggestions. I tried both wick and a sucker but no avail. I seen someone using the end of a match to penetrate the hole, I guess I'll try and work around it that way.
Do you think a poor connection could cause my slight channel imbalance?
That is what would make it a poor connection, IMO. IOW either an inadequate mechanical or high-resistance electrical connection. I would probably try to apply the soldering iron to one side of the board to melt the solder and insert the wire through the hole from the other side, then set about obtaining a good fillet.
To track down the imbalance it would help if you could disconnect the left channel wire from the ODAC on the O2 end, then jumper over the right channel connection to the left channel connection with a short jumper wire. That way you are feeding the right channel from the ODAC to both the right and left channel on the O2. Both channels then should sound exactly the same if the problem is the ODAC, otherwise the problem is with the O2.
The volume pot on the O2 is only accurate to about 20% between the two channels. The pot imbalance will show up the most at low volume levels. A way to correct that is decrease the value of R21, or R23 (Whichever gain setting you are using), to bump the gain in the right channel up a bit.
For example, if your R21 is 1K right now, you have 1.5K/1K + 1 = 2.5x gain. If you drop R21 about 10% to the next standard resistor value, 910 ohms, that would bump the right channel gain up to 1.5K/0.91K + 1 = 2.65x.
30 minute edit expire just passed, was going to add some photos into my previous post. I scrapped my CAT5 cable for connecting the ODAC to the O2. I just got some Van Damme Starquad Miniature microphone cable I'm going to use for a headphone recable so I cut a bit of that off and used it instead. A little bit overkill, perhaps, but it worked out well. Firmer cable, easier to solder.
As you can see, I made a bit of a dog's dinner of the ODAC soldering but I somehow got throughout without wrecking anything. I was able to coax enough solder out of the holes (but not 100%) and then force a long piece of unsheathed Van Damme through - I then bent it a little bit, soldered and then trimmed. My issue the last time was not having three pairs of hands to hold the CAT5 in place, the solder and the iron. The right channel's ground was an afterthought. I tried to get away with only using the L ground, but when I hooked everything back up I wasn't getting right channel. In my efforts to fix it, I hooked up the R ground but it turns out the issue was that the trace I cut on the O2 for the R channel had somehow got a little bit of solder in it. Fixed that up.
https://www.dropbox.com/sh/bf0c4uficuzn91u/GY1n0POL_-
As you can see, I made a bit of a dog's dinner of the ODAC soldering but I somehow got throughout without wrecking anything. I was able to coax enough solder out of the holes (but not 100%) and then force a long piece of unsheathed Van Damme through - I then bent it a little bit, soldered and then trimmed. My issue the last time was not having three pairs of hands to hold the CAT5 in place, the solder and the iron. The right channel's ground was an afterthought. I tried to get away with only using the L ground, but when I hooked everything back up I wasn't getting right channel. In my efforts to fix it, I hooked up the R ground but it turns out the issue was that the trace I cut on the O2 for the R channel had somehow got a little bit of solder in it. Fixed that up.
https://www.dropbox.com/sh/bf0c4uficuzn91u/GY1n0POL_-
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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.
Thanks for such a helpful response. By "accurate to about 20%" do you mean there could be a 20% difference in the channels? That seems a lot. I'm not sure how the measurements work.
Could a "better" pot be hand to reduce this difference?
RE: my hearing a channel difference, it turns out that I have some sort of ear infection as a result of tooth pain. Got an appointment booked for next week, really hope it isn't permanent!
My luck to buy a fantastic amplifier and DAC and then something happens that means I can't enjoy them!
Yep. And that is actually considered good for dual gang pots. Check out "total resistance tolerance" specification here:
RK097 Series - Basic information
About the only other thing is a stepped attenuator, a pricey panel-mounted gizmo about the size of a small pine cone:
High Quality Audio & Industrial Attenuators
Keep that O2 resistor modification in mind, if needed, to bump up the gain in one channel. Best of success with the ear exam!
