Peavey T-40 Bass wiring help?

sstanfield

sstanfield

Member
I have this bass from the mid 80's, and the pots are all scratchy - it needs some help. It has some pretty complicated wiring. Here is a description of the pickups and controls from the T-40 Forum I found:

Pickups- All Peavey T-40's have chrome rimmed ferrite (iron) humbuckers with a wide frequecy range and the ability to operate in humbucking and single coil modes.
-82/83 and later models have single magnet and exposed blade humbucking pickups. The single magnet design is more efficient and these pickups are noted for having greater attack and high end with more gain than the "toaster" style.

Controls- Two switches, a three way selector switch and "mystery" phase switch. Four knobs, consisting of volume and tone for each pickup.

Single coil options-Tone knob switches from humbucker to single coil at the "7" position.

Mystery Switch-Second "mystery" switch is an in-phase/out-of-phase switch that only works when both pickups are on. Brings a nasally honking sound to the bass.

I pulled the pickguard and all of the pots are 250k. I was looking through my parts bin and found four 500k push/pull switch pots. What difference would the 500kpots make to the sound. I would like to use something I already have if I can. I would also like to have this thing playable by practice this weekend (The bass we have been using lately is gone, as of yesterday.)

This thing is incredibly heavy, and I'm thinking about buying a Jazz copy body from Guitar Fetish (3 1/2 ibs.) I hope to use the 4-hole control plate with three of the push/pull pots (tone for both pickups combined) and a five-way selector switch for pickups. The jack is on the bottom edge.

Any advice or suggestions?
 
Re: Peavey T-40 Bass wiring help?

I would try cleaning the pots before replacing them. You can buy rheostat cleaner at Radio Shack. You just give each pot a squirt in the opening in the front or on the back of the pot. Most pots that aren't sealed also have four small tabs on the top which you can pry back to remove the wafer and shaft if necessary.

500K pots will be brighter and give a stronger initial attack than 250K pots. However they may not round out the sound like 250k pots do. I wouldn't want to waste the push/pulls if you aren't going to use them.
 
Re: Peavey T-40 Bass wiring help?

Push-pull pots may be too tall to fit inside the Peavey control cavity without fouling on the screening foil that lines the bottom surface.
 
Re: Peavey T-40 Bass wiring help?

idsnowdog, Thanks for the advice and information. I knew about the contact cleaner, but the nearest Radio Shack is in Flagstaff, two hours away. One of my bandmates is going there, however, so when he returns I'll try it.

I've had the push/pull pots for five years and I'm not likely to use them any time soon, so it was an idea worth considering.

Funkfingers, I tried setting them in the cavity, and I think they would work, and I was thinking I could insulate the shielding and the bottom of the pot with electrical tape, just in case. Thanks for the heads-up, though.

Anybody have an interesting schematic idea for wiring two bass humbuckers with coil splitting that would fit in the Jazz control plate?
 
Re: Peavey T-40 Bass wiring help?

With a 5-way blade, you won't need the push/pulls for splitting.
Adapt this diagram to automatically split the pickups in positions 2 and 4 (red and white connections for Duncan pickups - you'll have to find out what wires of your pickups relate to Duncan's color scheme):
http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=1h_1s_1h_1v_1t_5w_as



Or you could wire each pickup to a push/pull Volume like this:

http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=1hum_1vol_1tone_split

then take the Hot output and instead of going to the jack, send them to a 3-way Gibson-style toggle switch, the switch out to the Tone, and then out to the jack.
 
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