New t-40 owner needs help

Hey guys,
I just picked up a great T40 off E bay a few days ago. I sat down with her for a few hrs and gave her a good cleaning, and nice setup. I decided to also check out the electronics as well. I noticed the neck PU is working as designed. With the tone control all the way up it is a single coil and with tone control around 7 it is a humbcker. However the bridge PU is a different story. It seems to be stuck in single coil mode. The tone control acts more like a volume control. If I have the tone all the way up and tap on the rear most coil I get nice strong response. Not much from the front coil. Then I turn it down to about 7 and the volume drops dramatically and the front coil still does not come on. The rear one is still the stronger one. Am I making any sense? Anyone know exactly how this circuit works. I looked at the electronics and everything looks good. No loose solder joints or anything. So how exactly does the switching happen. Is there any component that can go bad in there that would cause these type of problems? Or do I have a bad coil in the pickup? I also noticed that the phase switch will mute the bass when I am using only the bridge PU. I think this is by design correct? That phase switch is meant to be used with both PU's selected correct? Well thanks for any help you can give me with this. By the way here is a pic..

Hi for all, I asker the same to Chip and this is him answer:

"Hello, It sounds like this T-40 was made after I left Peavey for more money at Fender. I have only recently found that after I moved on, the person they put in control of the guitar department knew nothing about guitars and did some things that were just plain stupid. This pickup, undoubtedly, has the chrome cover held onto the pickup by staking (dimpling) the ENDS instead of the bottom edges of the sides. This end-dimple intruded inwardly enough to either break or short out the connection between the two coils. He also eliminated the potting compound which had made the pickups bulletproof and without feedback. About half of the later-made T-60 & T-40s have, at least, one pickup with only one coil working. Since Peavey made no spare parts, it is only be someone parting-out a T-60/40 that make a few parts available.
Chip"

Wow,

You can't get a better more informed response than that!

Thanks Chip!

Vicktor is selling a LOT of T-40 parts, check the trading post!

Well that sucks.. I'll have to take the pickup out and inspect the dimpling of the casing. Thankfully the nexk PU works fine, which is the main one I thing most of us use. Thanks for the post..

I removed the pickup and tested it. Both coils work, good news. Turns out the phase switch was shorting out on part of the cavity shielding causing problems. I removed a bit of the shielding and coated the connections on the switch with liquid electrical tape and problem solved.. Works like a champ now.

Hi all,

New member here, that just picked up their first T-40. I seem to be experiencing the same issue. I'm pretty frustrated that the guy on Ebay promised that everything was working correctly when he sold it. The body is very clean, so I trusted him. He was either lying, or didn't understand how this bass is supposed to function..

The tone knob for the bridge pup acts like a volume control, and the pickup is muted if it is 'in phase'. based on the response above, I sort-of understand the issue, but I have no idea how to fix it.

Is this something that I can diagnose / fix my self? I'm not a techy guy... Or is this something that I should take to a pro? I need some guidance here.

Thanks all,
Kalev

Sorry for the late reply. The guys who inherited the guitar dept. lead positions at Peavey changed the wiring to insure that there would be problems. The signal wire should always enter the pot through the central terminal. Not understanding that, they may have saved an inch of wire and made it worse.

Shielding on 99%+ of guitars is a placebo that makes the owner feel warm and fuzzy, but is like an incomplete window screen. If there are any holes in the screen, the mosquito will find it. To be effectively shielded, the pots need cans around them, the shielded wires grounded to the cans, and nowhere open enough to allow electro-magnetic interference to sneak in. If it's not completely shielded, then a little bit of silver nitrate paint or aluminum foil will only be there to fool the buyer.

I am also a proponent of clipping the red center-tap wire at the tone pot, to allow higher overtones to flavor the sound. The tone system we used is embarrassing to me, now.
Chip

Hey folks,
My first time posting - proud owner of a pair of t-40s and now one t-60.

sorry about the necro posting, but I'm facing two issues with two different T series guitars, one very early toaster pickup black t-60, which just as the original poster listed, was presented on ebay as 100% good to go. the body and neck are in better shape than any I've ever seen of this vintage, and I'd really hate to send it back for what I'm sure is either a bad cap or just shorting to ground
Issue is this:
Phase switch when both pickups are selected - seems to work just fine. tone and volume pots appear to do exactly what they should. select just the bridge pickup, sound drops to about 1/15th of original volume. originally thought it cut out completely, but then I cranked the volume on the amp and i could just hear it. I've been over the schematic a few times, and contemplating a switch that is shorting to ground or bad caps, but I would imagine that either of those would prevent tone control switching to humbucker.

then on to the T-60 - Sadly, this is one of the newer blade models. it is in amazing shape, but again, the bridge pickup in any mode is almost totally silent. If I pull up on the tone pot (pull the knob away from the pickguard) when the tone knob is just about center, I can just hear it, but only just. I've got a replacement toaster pickup for it, and certainly the ends are dimpled, so it could well be that the connection was broken by dimpling, but something just doesn't seem right. already (foolishly) replaced the tone cap, thinking that the prior was just not letting anything through, but that made no difference. figured by the time I had it out of the circuit enough to test, I'd more or less have it completely out of the circuit anyways, so yeah. at least in this instance I kept the original. also have backup PU and selector switches.
Anyways, I've gone on long enough, I just have one last thing to say:

To Chip Todd - I've had and sold on about 6 basses in 2 years now, and out of what i have left, if the house were on fire, the t-40's are the ones that come with me. These were very recently introduced to me and I can't believe I lived this long without one. without two. OK, I'm hoarding them now.
Very, very well done.