Soldering Mystery

[sixtwentytwelve]

Well, at least it's a mystery to me! I'm installing a couple of vintage (not reissue) toasters in a newer 330. I tinned the leads on the neck toaster and they measure about 7.6 on my multimeter, but after I soldered the leads in place and tested them again, the same leads measured zero or close to zero, nothing coming out of the toaster. Unsoldered the leads, got a 7.6 multimeter reading again. The solder joints seemed good and shiny,and I have swapped out pickups before without any problem. The bridge toaster seems to be working fine by itself and gives a good strong reading on the multimeter post-installation, but the controls are acting funny ... the bridge volume knob does not kick in until the knob is turned close to maximum, but I am assuming (perhaps incorrectly) that this might have something to do with the "missing" neck pickup in the loop.

What would be the best way to troubleshoot this issue and ensure that I have trouble-free connections for the neck toaster to the pot and the Switchcraft toggle? The pots usually seem to be the toughest part to solder, but at least you can "see" whether there is good contact between the exposed lead and the pot casing. The toggle switch connection strikes me as tougher because it's much harder to confirm good contact visually and there's very little surface to work with. If the "other" wire that connects to the toggle at the same connection point as the pickup lead is not making good contact under the solder, would that shut the toaster down? I can't figure out why I'm getting 7.6 on the multimeter pre-connection and nothing post-connection. Maybe I should remove all the solder/leads from the Switchcraft toggle and start over from scratch on those connections? Any suggestions would be much appreciated!

[cjj]

Sounds like you're either soldering to the wrong place or shorting something out. A bad solder joint will increase resistance, not make it zero. If you're getting zero between the leads after soldering, something is causing the two leads to be connected elsewhere.

It is possible that while soldering the leads to the pickup, you got them too hot and there is a short in the cable going to the pickup. This could look like it only shorts out when soldered due to the position of the cable, i.e., when it bends a certain way, it shorts out.

Posting some pictures of the wiring/connections might help us figure out what's going wrong...

[jingle_jangle]

If what you're saying is that the pickup itself measures 7.6K ohms before you solder it into the circuit, and nearly unity when it's soldered into place, that's because you're not reading the pickup once it's soldered into place--you're reading whatever the path of least resistance is.

Whenever you're soldering to a larger surface (pot case or switch flange, to ground the braid), it should be clean and well-heated. I ALWAYS use additional paste flux, applied with a handy toothpick, for each joint and for areas like the pot case. Make sure the iron tip is clean. Soldering to a pot case with a 25W iron can be an exercise in frustration. I recommend a 40W iron or soldering station with a temp control.

If the solder flows out onto the case and doesn't ball up, you've got a good joint. If it flows into the strands of wire when you're joining two wires, ditto--good joint.

Lastly, the pot/volume issue is puzzling, unless somebody has replaced the original audio taper pot with a linear taper one.

[johnallg]

John, with the toaster not in the circuit (unsoldered, not pickup in) put your ohmmeter to the two spots you are soldering to (pup switch leg and body of the pot). My guess is the meter will read zero ohms. Tackle that problem.

Another thought - where is the pup switch and the volume controls? Are they turning the pickup "off"? That would give a zero reading, but then you said no output from the pup so I would think you tried the volume control. Concentrate on the above.

[winston]

It appears that your pickups are working fine, so by logical extension the issue is in the harness itself. I suspect that you have a blob of solder or a thin piece of wire jumpering the contacts on the switch that you have not noticed. I would remove the switch entirely and test its operation with an Ohm meter. If it is fine then I would connect the leads one by one according to the factory wiring diagram found on Rickenbackers corporate website. That approach should solve your problem.

Joey's Bass Notes http://www.joeysbassnotes.com/ is also a great resource for wiring schematics and problem solving even though it is bass focused. Joey can be contacted on the Rick Resource also.

I wish you good luck with solving this problem. Let us know how you make out with its resolution.

[sixtwentytwelve]

Thanks very much -- these are all very helpful suggestions. I will so some investigation and disassembly/reassembly and then report back.

[winston]

I trust that you will locate the issue and repair it. I am looking forward to hearing that you were successful and that you are able to fully enjoy your instrument once again. I wish you good fortune in that regard.

[sixtwentytwelve]

Following up on everyone's suggestions, I was definitely getting a bad multimeter reading from the flange and control pot for the neck pickup, but as indicated previously the pickup seemed good, so I tried desoldering everything and using some paste flux in the resoldering operation. Before I resoldered, I trimmed back a bit of the pickup lead to get some fresh wire. With everything reconnected and looking good ... same problem, zero output from neck pickup, ugh. Then I remembered that I had a spare wiring harness in the parts box ... swapped that in, connected the neck pickup ... still zero output! However, that suggested that something was wrong with the pickup, not the harness or the pickup connections to the harness. I took another look at the freshly trimmed leads and noticed that, right where the shielded lead went into the gray outer covering, there was a "hole" in the white plastic where it looked like the shielded lead might be making contact with the outer lead. It's not clear to me how I could be getting a good multimeter reading on the pickup with what appeared to be a hidden short, but I separated the wires further and wrapped the exposed area on the inner, shielded lead in electrical tape -- bingo -- solid multimeter reading upon reconnection, neck pickup fully functional.

Hard to say for certain, but I think I was probably dealing with both a poor connection at the switch flange on the go-round with the first harness and a short in the old pickup lead. The toasters are 1968 vintage and it looks to me like the quality of the white plastic shielding on the inner lead might have left something to be desired ... in any event, my 2009 Fireglo 330 is now jangling perfectly with a pair of 40-year old toasters and a set of gold guards and oven knobs (bad photo attached). Thanks for the great advice ... Paul W.'s recommendation to use additional paste flux when soldering makes an enormous difference in making fast-solid connections.