Replies to This Discussion

Permalink Reply by David L. on May 29, 2016 at 2:03am

Hi Brian,
Have you managed to get the circuit to work?

It is difficult to follow the wires in the photo due to the copper tape covering them in places.

Working through your questions - pots are normally pretty tough components which is why the back of one is used for the common ground.

Assuming the bits we are unable to see are okay I would guess the multiple soldering to the back of the pot has a cold solder joint within the blob of solder. (To solder to a pot rub the back with a file or coarse sand paper and then heat it and add the solder to give a nice shiny blob. Leave soldering the ground wires until you have them all ready. Twist all the wire going to the back of the same pot and tin the bare wire ie heat it with the soldering iron and then add the solder wire and it should drink up the molten solder into the wire strands. Finally place the tinned wire next to the solder blob on the pot (use a "helping hand" device which has two adjustable arms with clips so they are held in place whilst it heats and your fingers don't get burnt). Heat with the soldering iron and the blob and tinned wire solder should become molten and fuse as one area of solder. If you have too many wires to realistically twist into one big wire (which may be the case here) I would use a piece of electronics copper strip board as the common ground because each wire can then have it's own solder point along the board.

To check your solder joints with a multimeter you use the continuity setting (Google "multimeter continuity test" and look at the images and you should see the icon you need to set on the dial). If you have the probes in the correct connection point on the meter when you touch the probe tips together it bleeps. You now go around the circuit touching components either side of where there is a solder point. You move around the circuit systematically until you isolate where the faulty solder joint is. You can check large areas at a time if you wish to narrow the search down (eg negative off the mag pickup and negative on the Jack socket - a bleep there lets you know this part of the circuit is okay). Draw or print off the circuit you have and tick off each bit as it tests positive. Any non-continuous solder joints need redoing.

Copper tape is great to use as a shield on the inner surface af a box. I wouldn't use it to hold wires though because if it is grounded (a grounded pot passing through the tape grounds the tape) the circuit will immediately stop working if the positive signal connects with the grounded copper tape. So it could be the circuit is fine but at some point a positive wire is in contact with the tape. The positive lugs on a pot can often do this if a lug has moved downwards during installation. If this is not obvious on looking unscrewing the pot and pushing it back so it doesn't touch the tape will check this. The other place I have seen problems with a circuit shorting is at the Jack socket. Visually inspect this with and without a plug inserted.
Sorry for the long winded explanation (easy to show, hard to write down).
Good luck,
David
PS did you get the mini amp circuit working?

Permalink Reply by David L. on May 29, 2016 at 2:41am

This is the type of strip board I mean
http://www.bitsbox.co.uk/index.php?main_page=product_info&cPath...

Pick a small size because it can be hard to trim. You put the wire through the back so it comes out the copper strip side and solder. Each copper strip means all the holes along that strip are electrically connected. Once you have your completed common ground you add a final wire to the Jack ground lug. The strip board them needs covering in electrical tape to avoid any risk of a short circuit. I also tend to use a part of the board with no wires connected to screw through to fix it and stop it rattling in the box.

These are helping hands
http://www.ebay.co.uk/itm/Soldering-Iron-Stand-Helping-Hand-Magnify...
I am in the UK so you will need to google or eBay locally for the best price.

Regards,
David

Permalink Reply by darryl kernaghan on May 29, 2016 at 3:07am

I'm not sure if i'm seeing the pic's right,but if you feel all your joints are ok,try removing the ground at the left of switch,i've had issues with those switches before,the switch is still grounded via the tape anyway,that will eliminate 1 potential problem,you can still wire it up again if needed once you have a signal,if still no signal,undo the nut of the switch and lift it away from the tape,breaking the ground completely,the pot wiring is a bit hard to see,but if you run a wire [with alligator clips if possible], from the centre terminal of the switch to the hot terminal of the jack,that will confirm the pups output,cheap pots sometimes fail,especially after a lot of heat,but usually you'll get some noise,an easier way to get around that is solder just 1 wire to the pot,then solder the rest to that,with the tape method you've used,all fixtures should be grounded via that alone,barring the pups,the only other thing is confirm,the centre lug from the pot is going to the terminal that gets the tip of your jack when plugged in,actually,do that 1st,hope it helps

Permalink Reply by Rick Alexander on June 2, 2016 at 8:56am

I tried shielding one of my last ones similar to what I see in your pictures, and (long story short) removing a piece of the tape and breaking that "circuit" made it work. I had the bridge grounded to the pot to the jack with tape, and it didn't work.

Permalink Reply by Paul Craig on June 7, 2016 at 8:30pm

Looks like you have many issues going on.

Cold solder joints - need to get those hot enough for the solder to flow instead of puddle, Scuffing the surface and tin the surface before soldering wire is a good practice. Wire ends need to be clean as well, used wire can give you problems with soldering. Are you using the right solder? Need to be using Rosin Core Solder 60/40 or better for electronics. Plumbing style solder will not work. Go back over all the solder joints to make sure they are good. Make sure the positive circuit isn't shorted to ground somewhere. Used wire can also have breaks under the insulation that are hard to find and fix if you are using used wire.

If you have a ground wire going to all the components - ground tape isn't necessary. The ground tape could be shorting to the pins of the volume pot. Too much wire can lead to noise problems and it's good to twist the wires together for shielding.

Not uncommon for a new switch or pot being defective(not working or shorted).

You may know most of or all this stuff - disregard some of this. If not - take it all in.