Jimothey Posted September 10, 2018 Share Posted September 10, 2018 I'm trying to finish my 4 to 5 string conversion P bass so I'm trying to set the intonation and it seems like I've got no output? But here's where I'm getting confused when I plug it in to my little practice amp I don't get any sound except for a slight hum but if turn the volume knob down the hum stops then starts again if I turn the volume knob up again Am I being stupid or does that mean I am getting an output?? Quote Link to comment Share on other sites More sharing options...
KiOgon Posted September 10, 2018 Share Posted September 10, 2018 Sounds like something is earthing out to screening or wires shorting, a picture of the pots/wiring might help. John 1 1 Quote Link to comment Share on other sites More sharing options...
Grangur Posted September 10, 2018 Share Posted September 10, 2018 Seems to me you are getting an output, but maybe something is short-circuiting the pickup. Go over everything. Look for things like a long wire soldered to a pot touching the can of the pot. Also, if you've screened the cavity, take the pickguard off, connect up the bass, with the PG dangling off. Then see if it works. It's possible screening is touching something and shorting it to earth. 1 Quote Link to comment Share on other sites More sharing options...
Jimothey Posted September 10, 2018 Author Share Posted September 10, 2018 Thanks I'll take a pic and try lifting the pickguard off on my lunch break Quote Link to comment Share on other sites More sharing options...
HazBeen Posted September 10, 2018 Share Posted September 10, 2018 Have you shielded the cavity? If so you may be shorting the jack input if it touches the shielding. Quote Link to comment Share on other sites More sharing options...
Jimothey Posted September 10, 2018 Author Share Posted September 10, 2018 (edited) Here's the wiring, the ground to the bridge is a bit short so I can't really lift it off too far but that hasn't made a difference My other P is quiet without sheilding the cavity so I haven't done this one as yet Edited September 10, 2018 by Jimothey Quote Link to comment Share on other sites More sharing options...
KiOgon Posted September 10, 2018 Share Posted September 10, 2018 (edited) I can't see - is there a earth wire coming from the jack socket? Edit: Assuming the black I can see is going to the bridge! Edited September 10, 2018 by KiOgon Quote Link to comment Share on other sites More sharing options...
Grangur Posted September 10, 2018 Share Posted September 10, 2018 10 minutes ago, KiOgon said: I can't see - is there a earth wire coming from the jack socket? Edit: Assuming the black I can see is going to the bridge! Or is the black from the pot going to the jack and the green going to the bridge? Also, where the white/hot connection from the pup goes to the volume pot, the tag looks bent. Is there anything there touching the foil on the back of the pickguard? Quote Link to comment Share on other sites More sharing options...
Jimothey Posted September 10, 2018 Author Share Posted September 10, 2018 Sorry its a bit of a rubbish photo! All the blacks (numbered 1) are grounds they go Pickup - Pot - Pot - Jack (Sorry I'm colour blind so I might be completely wrong??) the thicker green (numbered 2) cable goes from the middle pin on the volume pot to the other pin on the jack then the cable (numbered 3) goes from the jack to the bridge I hope that make sense?? Quote Link to comment Share on other sites More sharing options...
Jimothey Posted September 10, 2018 Author Share Posted September 10, 2018 (edited) 5 minutes ago, Grangur said: Or is the black from the pot going to the jack and the green going to the bridge? Also, where the white/hot connection from the pup goes to the volume pot, the tag looks bent. Is there anything there touching the foil on the back of the pickguard? I checked all the pins, solder etc and nothing is touching the foil Edited September 10, 2018 by Jimothey 1 Quote Link to comment Share on other sites More sharing options...
Grangur Posted September 10, 2018 Share Posted September 10, 2018 That all makes sense. Thanks for that. You're clearly Red-Green colour blind, but we can work with that and it doesn't matter here. For your info; cable "3" is green. The other cables are red. So it's done in a logical-ish way. On that basis, it's not impossible that your up has gone open circuit. Do you have another pup you can connect? Quote Link to comment Share on other sites More sharing options...
Grangur Posted September 10, 2018 Share Posted September 10, 2018 it's possible that a good way to move forward next is to check the pup by removing the pup from the volume pot and connect it straight to a jack socket and find out if you get output then, Quote Link to comment Share on other sites More sharing options...
Jimothey Posted September 10, 2018 Author Share Posted September 10, 2018 (edited) No unfortunately I don't have any spares or a soldering iron on me but I've got a multimeter so can I check the pup by coming off the hot and ground and I don't get any readings then would that mean the pup is shot?? Edited September 10, 2018 by Jimothey Quote Link to comment Share on other sites More sharing options...
Grangur Posted September 10, 2018 Share Posted September 10, 2018 Yes, @Jimothey, that's about it, but you need to disconnect one leg of the pup from the circuit, otherwise you would be measuring the resistance of the volume pot. Or, do my other suggestion and connect the existing pup to a jack, and see if that works. This way you, at least find out if the pup is the issue, or if it's the circuit Quote Link to comment Share on other sites More sharing options...
Jimothey Posted September 10, 2018 Author Share Posted September 10, 2018 12 minutes ago, Grangur said: Yes, @Jimothey, that's about it, but you need to disconnect one leg of the pup from the circuit, otherwise you would be measuring the resistance of the volume pot. Or, do my other suggestion and connect the existing pup to a jack, and see if that works. This way you, at least find out if the pup is the issue, or if it's the circuit I'll bring my soldering iron in tomorrow and give that a go thanks @Grangur for the advice 1 Quote Link to comment Share on other sites More sharing options...
Jimothey Posted September 11, 2018 Author Share Posted September 11, 2018 (edited) @Grangur I did what you suggested and attached the pup straight to the jack and still nothing so I've just ordered a new pup nothing special as I'm still not 100% sure whether I'm going to change the neck to a standard sized 5 string and fit some 5 string split coils but they should be here in a couple of weeks so I can have a play about with it and see how I get on 😀 Edited September 11, 2018 by Jimothey 1 Quote Link to comment Share on other sites More sharing options...
Grangur Posted September 11, 2018 Share Posted September 11, 2018 Hey @Jimothey, somewhere I've got a really nice P-bass split coil pup. It's an American make. It sounds really good. The footprint is the same as a 4 string one, but it works with 4 or 5 string basses. If I can find it I'll let you know. 1 Quote Link to comment Share on other sites More sharing options...
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