Simon. Posted April 14, 2011 Share Posted April 14, 2011 Holla folks, I have an '86-ish MIJ Fender Jazz which was converted to fretless many moons ago, and after being my main bass for a long while has been stored in a flight-case for about 6 years. I recently decided to treat it to some new parts and transform it into a Bitsa special. The first stage was today, and after a strip down and clean, it was time to put in some new Wizard 64's. Installation of the pick-ups wasn't a problem, but I did discover what I believe to be some serious weirdness with the wiring configuration. First off, the two pick-up earths and the cavity/bridge earth wires were all connected to the body of the same volume pot, which isn't a big deal, but there were no earth connections to join between the two volumes pots and the tone control. Basically the Bridge volume & Tone pots were not earthed. Secondly, and majorly odd, was the fact that there was no earth connection to the jack socket, only a 'hot' wire. By the looks of it there had never been either, as there was no solder residue on the earth tab of the jack socket. Last off, the tone cap is wired from the centre (hot) tab of the tone control to the hot tag on the jack socket. I was pretty sure the tone cap was supposed to be between the earth tab of the tone pot and the general earth connection? Based on a BassLine wiring diagram, I've sorted the first two issues, but wasn’t 100% sure about moving the tone cap. Any thoughts? Cheers. Quote Link to comment Share on other sites More sharing options...
tommorichards Posted April 14, 2011 Share Posted April 14, 2011 Bam. Below is normal wiring on the jazz. Does sound strange... Did it work properly when you used to use it, or while in storage did someone mess with the wiring to mess with your head? Quote Link to comment Share on other sites More sharing options...
BOD2 Posted April 14, 2011 Share Posted April 14, 2011 On a Jazz bass, since all of the controls and the jack are mounted on a metal plate, the metal plate itself acts as a ground connection between the jack and the pots. This method does rely on good contact between the pots/jack and the metal plate and it's usually advisable to add the actual ground wires just to be sure. Some people will then point out that this creates extra earth connections, and that it actually creates a "loop" of earth wires between all the controls - a "ground loop". However... it's not this type of ground loop that causes problems in sound equipment and poor earthing, due to the wires actually missing, is more likely to cause problems than these so-called "loops". Quote Link to comment Share on other sites More sharing options...
Simon. Posted April 14, 2011 Author Share Posted April 14, 2011 Hi guys, thanks for the quick responses! tom - that wiring diagram is identical to the BassLines one I was using as a reference, so it good to know I was on the right track. BOD2 - Using the control plate as the common earth does make a lot of sense, especially if you are trying to cut costs, which I guess might have been one of the aims on Fender Japan. It's been a lot of years since this bass was played, but I don't recall having any real problems with it when it was in action. I [i]think[/i] it did suffer a bit with earthing issues/noise, which was one of the reasons it went off into storage. I always thought the pick-up outputs were rather feeble, which hopefully the 64's will improve upon. The tone cap position is a weird one. I'll put it all back together first and try it out, and then see what difference moving it to the correct position makes! Thanks again folks. Quote Link to comment Share on other sites More sharing options...
icastle Posted April 14, 2011 Share Posted April 14, 2011 [quote name='Simon.' post='1199452' date='Apr 14 2011, 02:34 PM']The tone cap position is a weird one. I'll put it all back together first and try it out, and then see what difference moving it to the correct position makes![/quote] It does the same job, albeit it in a rather cack handed way. From your description of pots not being earthed together and a single wire going to the jack socket, I'm guessing that they were trying to avoid soldering onto pot casings where possible. Quote Link to comment Share on other sites More sharing options...
mart Posted April 14, 2011 Share Posted April 14, 2011 +1 to icastle's reply. In the circuit linked by tommorichards above, the tone filter circuit takes the signal from the hot wire, through a variable resistor, then through a cap, and to the ground. As your bass is wired, the circuit takes the signal from the hot wire, through the cap and then the resistor, before going to the ground. The different order makes absolutely no difference to the way the circuit works. Quote Link to comment Share on other sites More sharing options...
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