Banjoman Posted November 10, 2022 Share Posted November 10, 2022 Hi there, I hope someone can give me some advice. I'm trying to get a Tokai Jazz Sound up and running. A bass that has great sentimental value. There is no sound coming out when it is plugged in, just a buzz. There are three pots, I have opened it up and there are two A250k pots and one marked 6382 250k. I presume thats two volumes and a tone. The ground terminal of the jack has no wire but there is continuity with the metal plate. One of the a250k pots only has one wire going to it which links straight to the pos jack terminal. This pot also has a wire on one terminal which is soldered on to the pot with a473z capacitor in line. There is continuity from the body of the pot to the ground of the jack. This looks unusual to me but then I don't really know anything about bass wiring! Or is it something different like dead pick ups? Any thoughts any one? Quote Link to comment Share on other sites More sharing options...
Chiliwailer Posted November 10, 2022 Share Posted November 10, 2022 Your Jack socket needs an earth and a live connected to it, looks like it’s not got an earth. If you type ‘Jazz bass wiring’ into Google and do an image search then you’ll find a wiring diagram (can be a few ways to wire it) - or wait a while and no doubt a BC’er with more time will give you a more in depth answer! Quote Link to comment Share on other sites More sharing options...
Banjoman Posted November 10, 2022 Author Share Posted November 10, 2022 Thanks for your reply. That was my first thought but the plate that the pots are mounted on appears to be doing the job of the earth wire. There is continuity from the plate to the earth terminal and no signs of there ever having been a wire soldered on there Quote Link to comment Share on other sites More sharing options...
Bigguy2017 Posted November 10, 2022 Share Posted November 10, 2022 As well as can be seen from the photos, the wiring appears correct. The control plate, pot bodies and jack sleeve are all common ground, with a plain wire to the bridge earth. Make sure all the pot and jack nuts are nipped up tight. It's possible the pickups are not working. So, do you have a soldering iron? Do you have a DVM? If yes, then unsolder black and white pickup wires from the pots and use DVM on Ohms/resistance range to test the pickups - they should read around 6K. If not, you need to make up a test cable - normal mono jack to croc clips - if no croc clips then twist wires together.... plug jack end into amp, clip (or twist) black and white pickup wires (one pickup at a time) to other end of cable. Does the pickup work? Test both... If pickups are OK then (obviously) it's a fault with the pots or wiring. (The top pot looks like it has been replaced in the past). Use DVM to measure pots - expect 250K or thereabout. (DVM across outside lugs reads the track - 250K, outside to centre should vary with knob position 250K to 0) I pickups and pots are OK then it's a (simple!) wiring problem - take a very good look at all the joints and follow the wires - re-do the solder joints... See attached wring diagram - you are using the LH version. Jazz Bass WIRING 01D.pdf Quote Link to comment Share on other sites More sharing options...
gary mac Posted November 10, 2022 Share Posted November 10, 2022 Even with a metal plate, I still prefer to also rely on a ground to the jack. 1 Quote Link to comment Share on other sites More sharing options...
Bigguy2017 Posted November 10, 2022 Share Posted November 10, 2022 You can test the pots and wiring this way... remove the pickup leads from the pots (two white, two black) plug bass into amp - adjust volume (!) touch the centre lug of a volume pot - big hum on amp - turn pot - does volume pot work? Turn tone pot - does in alter 'tone' of big hum? If all the above work then the pots, jack and wiring are functioning correctly. Quote Link to comment Share on other sites More sharing options...
Banjoman Posted November 10, 2022 Author Share Posted November 10, 2022 Excellent replies, thank you! I have a soldering iron and meter. I will have another look at it and get back to you all in the next day or two. Quote Link to comment Share on other sites More sharing options...
Banjoman Posted November 10, 2022 Author Share Posted November 10, 2022 Last question before I start on this. What are the chances of there being two dead pick ups? As far as we know the bass was working properly last time it was used but unfortunately the original owner is no longer with us, I'm trying to get it working again for his sister. Quote Link to comment Share on other sites More sharing options...
Chiliwailer Posted November 10, 2022 Share Posted November 10, 2022 7 minutes ago, Banjoman said: Last question before I start on this. What are the chances of there being two dead pick ups? As far as we know the bass was working properly last time it was used but unfortunately the original owner is no longer with us, I'm trying to get it working again for his sister. Slim, but I think someone posted on here in the summer that heat had melted the pickup connections, IIRC. You could wire them to the jack directly to check out if they are ok or not. Quote Link to comment Share on other sites More sharing options...
KiOgon Posted November 10, 2022 Share Posted November 10, 2022 Sorry, late to the party! Good advice above and as said the wiring looks OK. Many manufacturers don't or didn't bother with a earth wire to the jack when mounted on a metal control plate, but as Gary - I always do a hardwire earth to every component, it only takes one to become loose and you can loose the continuity. Testing everything with a multimeter should find the problem/s. Good luck 😉 If you decide on a new loom, easy option, ☺️ I'm here 1 Quote Link to comment Share on other sites More sharing options...
Banjoman Posted November 10, 2022 Author Share Posted November 10, 2022 Ok, I have desoldered both pick ups and there is no resistance reading on my meter. Also there is no continuity at all through the pick ups. Is that normal? I have touched the ends to a jack lead plugged in to an amp and there is just a buzzing. Both are the same. Quote Link to comment Share on other sites More sharing options...
KiOgon Posted November 10, 2022 Share Posted November 10, 2022 Definitely not normal, idealy - do you have another pair of pickups you can try? If you can inspect the external solder joints where the pickup wires are and the wires are in tact, the probability is that the coil windings have for some reason been broken/damaged or detached from the solder tags inside. Quote Link to comment Share on other sites More sharing options...
tauzero Posted November 11, 2022 Share Posted November 11, 2022 You should be seeing something from maybe 8k ohms to 16k ohms from each pickup. That order of magnitude, anyway. Can you extract the pickups and check the wires at the other end? Quote Link to comment Share on other sites More sharing options...
Banjoman Posted November 11, 2022 Author Share Posted November 11, 2022 I will remove the pickups later today and inspect them Quote Link to comment Share on other sites More sharing options...
Woodinblack Posted November 11, 2022 Share Posted November 11, 2022 How long has it been sat since it was last working? Quote Link to comment Share on other sites More sharing options...
Banjoman Posted November 11, 2022 Author Share Posted November 11, 2022 I would estimate 5 years. Quote Link to comment Share on other sites More sharing options...
Banjoman Posted November 11, 2022 Author Share Posted November 11, 2022 I have removed a pick up. The wires are firmly connected, continuity through the wires but not through the pick up. Looks like we have two dead pickups.🙁 Quote Link to comment Share on other sites More sharing options...
Hellzero Posted November 11, 2022 Share Posted November 11, 2022 Refresh (recharge) the solders on the pickups side first as they could have become dry over the years. If it's still not working and you're not reading any resistance (somewhere between 6 and 8 kOhms), then they are dead and should be rewired or replaced... Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted November 16, 2022 Share Posted November 16, 2022 That two pickups would go open circuit is highly unlikely. 1 Quote Link to comment Share on other sites More sharing options...
prowla Posted November 18, 2022 Share Posted November 18, 2022 You could try touching the multimeter pins to the pickups solder points on their underside rather than the other end of the wire. 1 Quote Link to comment Share on other sites More sharing options...
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