Blend pot making a massive buzzing noise when I touch it

[StevieD_FenderP2009]

Hi guys

I've got a problem with my Tobias and it's new pre amp. I've got a Spector tone pump 9v pre amp running in my Tobias now and the tone is a billion times better. I've wired the bass as the diagram from Piotr Michalik told me to but for some reason, the blend pot is making this really loud buzzing noise when I touch it. If I earth the pot to the bridge earth cable, it stops the bass making any sound what so ever so what do you suggest?

Please help me! This is my main gigging, recording and EVERYTHING bass so I need it to work.

Cheers
Stevie

edit: here's the diagram I used:
[attachment=88986:Tonepump_diagram.png]

Edited September 8, 2011 by StevieD_FenderP2009

[mart]

[quote name='StevieD_FenderP2009' post='1366975' date='Sep 8 2011, 08:58 PM']... the blend pot is making this really loud buzzing noise when I touch it.[/quote]
This makes it sound like you need to earth that pot. You should try that first.

Oh, wait, you've already done that:
[quote name='StevieD_FenderP2009' post='1366975' date='Sep 8 2011, 08:58 PM']If I earth the pot to the bridge earth cable, it stops the bass making any sound what so ever so what do you suggest?[/quote]
This says, to me, that either:

1) when you earthed the pot, you connected the earth wire to the wrong part of the pot. I got caught out once because the bottom face of the pot was actually attached to the wiper, and the earth connection needed to go to the side, not the bottom. I can't remember exactly, but I suspect that was on a blend pot.

or

2) something else is wrong in the way you've wired up the blend pot.

[StevieD_FenderP2009]

I've tried sending an earth wire from the casing of the pot as well as trying it on the 6 connector pins coming from it. The pot it's self has been wired exactly as the diagram shows.
Do you think it could be a broken pot? Also, the only earth wire going to the blend pot in the diagram seems to be one of the 2 wires coming from the pre amp which is how I've wired it in as said.

Edited September 9, 2011 by StevieD_FenderP2009

[Beedster]

[quote name='StevieD_FenderP2009' post='1366975' date='Sep 8 2011, 08:58 PM']The blend pot is making this really loud buzzing noise when I touch it.[/quote]

Don't touch it then

[StevieD_FenderP2009]

I'd rather sort the problem out to be honest, this is my main bass and I don't want to go in to the studio with it and get told that half way through a take where I accidentally touched it that I got a huge buzzing sound come through.
I really need to sort this out guys!

[mart]

From what you've described, I think that the casing of the blend pot is electrically connected to one of the live parts. Yes, this [i]could[/i] be because the pot is faulty, but unless you're expert at soldering, it's much more likely that you have unintentionally made this connection when wiring the pot. (That's certainly what I would assume if it happened to me, cos I don't consider myself expert at soldering). This could happen by a tag being bent over slightly too far, or the wire having a little too much bare wire showing that then bends round and touches the case, or there could be too much solder on one tag, so it has spread and reached the casing, ....

If you're 100% confident of your soldering abilities, then go ahead and buy a new pot. If it were me, I'd de-solder and re-solder every connection to the pot.

(If you do re-solder the connections, you could save some soldering work by doing some more diagnostics first: if you turn the blend pot fully clockwise does it still buzz when you touch it? What about fully anti-clockwise? If it still buzzes in [i]both[/i] of these positions, then I think your problem is with the two opposite corner tags that are joined by the short white wire. If not, and it works ok when the blend pot is turned fully one way or the other, then it's one of the two centre tags that is the problem).

[StevieD_FenderP2009]

Thanks for the advise buddy, I will definitely have a go at doing that. I wouldn't say I'm the best at soldering but I'm definitely competent enough to do it. I'll have a go at eliminating the problem and see what it is.

I'll update this once I've done it
Cheers!

[StevieD_FenderP2009]

Just as an update, it's stopped working for some reason. I've tried 2 blend pots and it didn't work at all but when I connected the pick ups directly to the pre amp it did so I'm going to be wiring it to have 2 volume controls instead of 1 volume and 1 blend. I don't understand why it won't work with a blend pot but that's how it is so i'll have to try another way but if this doesn't work then i'll be scrapping the pre amp and getting a new one from somewhere. List of different pre amps i'm thinking of are:
Bartolini HR4.6 NTMB-918F 3-band Preamp/ Tone Control Module (Volume, blend, treble/bass stack, mids)
Bartolini HR4.5 NTBT-918 2-band Preamp/ Tone Control Module (Volume, blend, treble, bass)
EMG BTS system (Volume, blend, treble, bass)
EMG BQC system (volume, blend, bass/treble stack, mids)
Seymour Duncan STC3A 3 band EQ system (volume, blend, bass/treble stack, mids)

Whichever pre amp I pick or whether I end up sticking with the one I have (I'd rather do that if I can) I'll be using Seymour Duncan ASB-BO5 pick ups with it so my treble is going to cut through niiiiicely!