indentifying some old p90's

[massaloch]

I picked up a couple of p90s off of craigslist that I'm trying to identify. At $10 for the pair I intended to buy them to sacrifice as dummy coils (advertised as generic non-gibson), but was suspicious as soon I got back in my car and took a serious squint at them. A local guy who generally knows his stuff thinks they're late 40's early 50's, largely based on the black dog-eared covers - narrow, shiny, round-cornered, vacuum molded (as opposed to wider, matte-ish, less round cornered, injected), but for the lack of tabs on the bottom plates. This was confirmed by a bit of research on my part, in books and on the net, but no mention of them lacking tabs until soapbars came around. There any indication that there were. Consequently I cant imagine these were in a hollowbody, and I wonder if early solidbodies might have used dogeared covers but have pups with tabless baseplates. On the top of the pups themselves, there are holes where one would expect them on soapbars for mounting, but early soapbars were mounted in the corners, presumably for lack of just such holes ... not to mention the plastic covers are definitely of the early variety ... crossover pups maybe? Could be that the plates were changed ... someone certainly took the plates off, because between the plate and the magnets there are (were - I removed them) shims about as thick and wide as a popsicle stick. No idea what the intent was, but the effect was that the center rail was no longer flush with the plate, and when screwed down, the shims pressed into the bobbin and cracked it down the center, pretty badly on one, less so on the other). Fortunately, still reading 8.6k on one and 8k on the other. Any clues? Mainly intellectual curiosity - I love a mystery - though at some point in the future I wouldn't mind finding an appropriate gibson project guitar to put them into ... though I do have an epi '56 goldtop that might have been gettng a pair of sd stacked p90's ... mark

 

[ES350]

Re: indentifying some old p90's

Early covers are indeed rounded on the edges, are clear plastic painted black on the inside, slightly flared sides, and have a small recess on the ends for the dogear tab. These were in production until around 1948, but old stock shows up till around 1951. There are no soapbar covers that look like this. There were no Gibson archtops from that period that used soapbars or tabless dogears (no way to mount them), unless you think they might be early Guild Franz P90's. But those Franz pu's look very different from Gibsons and almost never read that hot (they run about 5 to 7 K).

It sounds like you have a mixed bag---soapbars (??? age) with some old covers from the late 40's-early 50's. Since the soapbar mount did not exist in the late 40's, there are no taps for the mounting screws through the bobbin (at least on the three or four that I have from that time). But who knows?
If you had some pix, we might be able to suss it out...

 

[massaloch]

Re: indentifying some old p90's

thanks for the interest!

I've posted photos at

http://s69.photobucket.com/albums/i79/massaloch/

One of the pups had double-sided foam tape holding the pup in the cover and I haven't yet tried to separate it.

2 questions: I want to solder leads to it - individual leads or shielded 2-conductor wire? There's not much to work with so I want to do it right the first time. How would I do it properly w/o jeopardizing the pups in some way. I might temporarily put the pups into my epi (soapbars), but eyeballing the pup agains the covers on my epi, I think the baseplate may be a little big (in the corners). More permanently, I'd use the pups and covers together, and suppose I would need tabbed plates ... suggestions?

Thanks
Mark

mark

 

[ES350]

Re: indentifying some old p90's

The pu's are real...German silver baseplate, M55 magnets, heavy steel keeper, rubber grommet, Single ply black top and bottom bobbin with round corners...looks like mid 50's. Yes, the baseplates are too square in the corners for most modern P90 routs (even Gibson Historics).

The covers are real, but are earlier ('46-'51) and don't match the pu's. Late 40's P90's have thin BWB laminate bobbins (leftover pickguard material?). Can't be mounted like this without wrecking something...The double sided tape was an doomed attempt to mount them. Do it right---get some nice repro soapbar covers or some SD dogear bases, depending on what you want to end up with. Those pu's are too good to screw up with a cobjob widgit fixit. Might want to attend to that broken base with the exposed coil too...cut a piece of similar plastic to fit and glue in carefully...

As far as leads, you need a couple of the solder ground tabs that goes under one of the baseplate Philips screws...use some nice flexible Lenzite (standard Gibson wire) and leave some slack on the hot lead after you shrinkwrap it. Let me know if I can help...

 

[massaloch]

Re: indentifying some old p90's

thanks for all the info - just the sort of analysis I was looking for! I'll stash it away into my guru folder

Hmmm - for starters, since they covers and pups are mismatched, I dont mind separating them, if not forever then for a while. Given I've got an epi '56 goldtop I guess it'd be appropriate as anything to drop them into there. However, not sure if I want to route out the body At some point I'd like to find a project hollowbody to put them into, at which time I'd swap bases, but that wont be anytime soon.

Any suggestion for repro covers? If it's just the baseplates that are a size issue, would it be sacrilege to use the baseplates off of my epi's p90's, provided they fit appropriately? I guess my concern is whether or not the current baseplates and/or repro covers will require some routing on the guitar. Not that a big deal, but would just as soon avoid it?

Any idea why on one pup the leads are w/w and the other b/w? They didn't differentiate between bridge and neck pups, did they?

Once the fit is settled one way or another, I'll worry about soldering it. I'm assuming Lenzite is shielded two conductor wire? How does one differentiate between hot and the ... er ... not hot ? Visually (ie where they drop out of the coil?) I wouldn't mind if they humbucked in the center position either (my house is really noisy, hum-wise, hence the initial search for p90's to gut for dummy coils ... I might just try a couple of cheapo strat pickups). I've got a push/pull doing phase switching on their now, and that certainly helps.

Thanks again!
Mark

 

[ES350]

Re: indentifying some old p90's

The wiring varied a bit--some are B/W, some W/W...no, they didn't specify bridge or neck pu's back then. you can dummy rig a wiring jig to see what's in and out of phase in combination. Repro covers...most Gibson covers will fit with a little cutaway over the side flanges. Old P90 covers fit with no problem and these can be found on occasion...

Lenzite is the braided single conductor wire used on almost every Gibson guitar until pretty recently. It's got a heavy shield and a single conductor. Heavy duty, lasts forever; best stuff for repro work. SD uses it, some lengths available from blown junker pu's, old wiring harnesses, HT leads in TV chassis, phono leads, some new stuff available on the net. DO NOT get the lookalike with a plastic coating on the interior conductor--it melts and you get interior shorts. Get the cotton braided push back stuff...

BTW---no guru here; I've just been using P90's since the early 80's when they were dirt cheap (5$) and rebuilding them. My main guitar (kinda retired these days) is an old ES350, so that's the tone where my heart is...have fun.

 

[massaloch]

Re: indentifying some old p90's

well, the pickup that was taped to the cover is in sorry shape - it needs a professional. I spent 45 minutes teasing it from the cover by parting the foam tape, whose consistency is that of a cooled-down melted marshmallow. At least it was foam tape with some thickness that could be "filleted". The top is cracked lengthwise all the way into three pieces - two "wings" on either side of a narrow piece along which the poles are set. The bottom piece it split down the center. The top is complete if not intact, while, as you noted, the bottom has two wedges of plastic missing. The windings are a bit loose, with a few odd strands straying out a bit and - ack! - there's a strand or two stuck to the foam tape. Still reading 8.06k - phew. If I knew what kind of chemical I could use to disolve the tape but not the plastic and whatever the insulation on the wire is (enamel?) I could clean it up, and then glue the fragments together (what kind of glue?), but not sure how to deal with the windings, nor the black tape wrapped around them. In short, I'd sooner someone with experience brought it back to it's full glory ...

So ... you've been rebuilding p90's for a couple decades, huh?

Mark

 

[ES350]

Re: indentifying some old p90's

That's a dicey situation with the wind stuck to the tape...easy to blow the coil. The top of the bobbin can be repaired with a little gentle refitting and a nice neat glue job with a little bit of cyanocrylate (doesn't melt insulation). It won't be pristine, but it's far from it now...

as far as getting the tape off, a light dose of lemon oil or a petro-based cleaner may loosen it up more, but teasing the coil wire off will be tricky. If you need to rebuild/rewind it, Lollar or Fralin do a nice job. If you need some old P90 soapbar covers, I have some 50's-60's, mostly in black; maybe we can arrange something.

 

[massaloch]

Re: indentifying some old p90's

got the coil wire off the foam tape. wasn't adhere really - just looked scary. I'm going to take a stab at it and have a few of questions before I dive in.

Given that the problems are:

- tape goo
- bobbins broken and need gluing
- coil loosing up a bit - sorta sprung along the axes of the poles, but not much, leading to:
- a few outer strands - maybe a dozen - orbiting a ways out of the edge of the bobbin, meaning I suppose that were I to follow those strands around, they'd have been pulled inside the coil elsewhere
- tape isn't corraling the windings fully

I'm thinking about order to do things in. goo removal will come last because the pickup needs to be pretty solid and stable before a manipulate it much. The windings wont really be controllable until the bobbins are glued, so I suppose I should glue before tackle the windings. So:

- glue
- corral windings
- apply some sort of tape to augment the existing tape
- goo removal

'm worried about glue getting on the coil underneath the bobbin and will prob slide some paper between the plastic and the wire unless there's a better way to approach it; I figure better to leave a little paper glued to the plastic that windings ...

what do I do to tame the stray strands? I imagine I should avoid crimping them, but anything else? More generally, how much will in matter that the coil is slightly loose or scattered?

what kind of tape would be appropriate? I use the word "tape" loosely - the only part of the tape that will be have adhesive is the part that overlaps itself, as opposed to getting the windings stuck to the tape ... been down that road already

Mark