A look inside a Lane Poor MM5.

[belwar]

Well here is a rare oportunity for some of you.. I decided to hack apart my Lane Poor MM5 (which by assumption is near identical to the MM4). I photographed everything as I went, and I have the high res photos if anyone really wants one.

I haven't taken measurements of the bobbins yet, that will be the next time I get bored... Anyway here goes. I used a large belt sander with a 60 grit belt to grind through the layers. Very tough to do as the magnets stick to the metal platten.


Picture 1: Here is the outside of the pickup, the MM4 is in a musicman style case, but the MM5 is put in the soapbar style casing.



Picture 2: This picture is the first layer when you sand through the top. The whole pickup is encased in thin brass shielding soldered to ground.



Picture 3: Bottom view of the pickup (serial number removed).



Picture 4: Here is a side view. What you can see is that the "shell" or case of the pickup is harder. The inside is more silicon like, while the outside is cured very hard. Two completely different materials. The outside sands very easy, but the inside is very gummy.



Picture 5: Bottom view of the pickup, again more shielding..



Picture 6: I've slowly picked away all of the silicon from the foil, and now you can see the ground wire soldered to the foil, You can also see that the foil is tightly held together with solder. Very nice looking.



continued....

[belwar]

Picture 7: I've removed the foil from the bottom of the pickup. Immediately you can see there are two distinct bobbins. The bobbins are made from single side copper clad circuit board. There are two small pieces of circuitboard glued to the bottom of the two bobbins to hold it together for assembly. Its wired like a standard humbucker. End to end connected, start 1 is hot lead and start 2 is ground. Like me, you are probably gathering by now that it is NOT a side

winder.



Picture 8: There is a small little brass insert thingy that holds the two wires in place.



Picture 9: Top of the pickup, foil removed



Picture 10: THE MONEY SHOT. I've sanded through the copper on the top of the bobbin, and now you can see the inside of the pickup. It's a standard humbucker, no poles, wire wound directly around ceramic magnets. Sloppy bobbins.



Picture 11: The underside, sanded slightly more. Note that part of the copper on the circuit board is removed. This creates an area where the leads can be soldered. There are no holes in the bobbin. The wires are brought around the edge of the bobbin.



Picture 12: Closeup.



Picture 13: Closeup 2

[belwar]

... and lastly

Picture 14: Side view of bobbin.

[David Schwab]

Interesting, and kind of what I expected.

What was the DC resistance reading on this one?

[David King]

Well after all that speculation don't we all feel a bit silly? I know I do.

These are very smart from a production standpoint but I find the copper cladding and the brass foil a bit redundant. I'll bet Lane was hoping to get by with just the copper but needed to add the brass when the noise still hadn't abated completely.

What are the dims on those magnets? are the super powerful or just ho-hum i.e. C5/C8 or maybe C2?


I take it the wire is plain old 42 single SPN?

[jonson]

not too far removed from Kents potted pickups other than coils wound on mags and Kent wrapped in ali foil.

[David Schwab]

Originally Posted by David King

Well after all that speculation don't we all feel a bit silly? I know I do.

I'd like to see one of the side winders... but this is what I expected of the humbuckers, and said so back in one of the original threads on LP pickups.

So I get a cigar!

Seriously though, this is what they sounded like to me. Low inductance, low turns pickups. My first prototypes from 4 years ago were made like this. That led me to the old forum where I was trying to find out why they were so low output! Of course they were also lo-z.

[Possum]

Where are the alien bodies now that we know how the craft operates :-) What is the deal with these pickups, did some famous bass player use them or something, I've never heard of these before. This is like watching a CT scan.....

[Joe Gwinn]

Originally Posted by belwar

Well here is a rare opportunity for some of you.. I decided to hack apart my Lane Poor MM5 (which by assumption is near identical to the MM4). I photographed everything as I went, and I have the high res photos if anyone really wants one. ......

Picture 4: Here is a side view. What you can see is that the "shell" or case of the pickup is harder. The inside is more silicon [rubber?] like, while the outside is cured very hard. Two completely different materials. The outside sands very easy, but the inside is very gummy.

Someone knew what he was doing. The soft potting is required so that the unit won't over time tear itself apart from the effect of temperature variation on mismatched temperature coefficients of linear expansion.

The potting material may be a silicon rubber or a urethane. The easiest way to tell is to burn some. If silicon, the ash will literally be sand. Urethane will burn completely, leaving little or no ash, unless there was a filler of some kind. One can also usually tell from the smell of the smoke, if one has samples with which to compare.

The shell is likely an epoxy or a polyester, unless LP had them injection molded. If the shell material melts when touched by a soldering iron, the shell is injection molded. If not, it's probably cast epoxy or polyester. Again, the smell of the smoke will tell.

[David King]

Interesting set of tests Joe. Thanks for that. Polyester almost never looses it's styrene smell even decades after it is cast. For that reason, I'm pretty sure that the outer potting is epoxy or polyurethane. I know the Lane cured the pickups in an oven (twice if that article is accurate) and that would lead me to believe that both the inner and outer matrixes were epoxy based.

David, good point, I'd missed that this particular pu was an HB.

[Sheldon Dingwall]

Originally Posted by Joe Gwinn

Someone knew what he was doing. The soft potting is required so that the unit won't over time tear itself apart from the effect of temperature variation on mismatched temperature coefficients of linear expansion.

The potting material may be a silicon rubber or a urethane. The easiest way to tell is to burn some. If silicon, the ash will literally be sand. Urethane will burn completely, leaving little or no ash, unless there was a filler of some kind. One can also usually tell from the smell of the smoke, if one has samples with which to compare.

The shell is likely an epoxy or a polyester, unless LP had them injection molded. If the shell material melts when touched by a soldering iron, the shell is injection molded. If not, it's probably cast epoxy or polyester. Again, the smell of the smoke will tell.

I'd really like to know what the inner compound is. The outside IIRC was epoxy.

Joe, do you mean silicone rubber (I've never heard of silicon rubber)? If that's the case, how would you tell?

I'm still looking for an RTV potting compound.

[David Schwab]

Originally Posted by David King

Polyester almost never looses it's styrene smell even decades after it is cast.

This is true! I broke open a non working Bill Lawrence pickup once that had to be 20+ years old, and I could smell the polyester resin.

I'd like to know what's in the pickups too. I use potting epoxy... don't know if that's different from normal epoxy. It cures hard.

[David King]

Originally Posted by Sheldon Dingwall

I'd really like to know what the inner compound is. The outside IIRC was epoxy.

Joe, do you mean silicone rubber (I've never heard of silicon rubber)? If that's the case, how would you tell?

I'm still looking for an RTV potting compound.

It could be Devcon Flexane
ITW Devcon | Two of the most recognized brands in all of industry; Devcon® and Permatex®.
though I don't see a need to heat cure that. There's probably a gummy-setting epoxy out there that works as well for less $$. Maybe Lane just shorted the hardener ratio?
I found this place Hexion.com - Epoxy Elastomer Modified Resins - EPON
I also saw a couple of patents regarding elastomer epoxies. Add a hundred parts Bisphenol A to the mix and go.

Any of the two part silicon RTV casting resins would accomplish this as well.
John Greer- Silicone Mold Making Rubber, RTV Molding Rubber

There's also a latex option from JGreer too.

[David Schwab]

He might just bake it to make it cure faster?

[Possum]

OK I googled Lane Poor, now I know. They are cool because you can't get them anymore Another myth busted.

You might look into jewelry supply websites and look for injection mold making materials. There are all kinds from RTV to stuff that bakes at around 300 degrees. I think he must have had injection covers made, would be a pain in the butt to do a double molding affair. The filler though looks odd, like sandy, maybe just an artifact of how Belwar sanded them?

[Possum]

Are the coils completely solidified?, It looks like it from the top, if they are he was using something water thin to pot the whole pickup, I've never encountered anything like that, maybe he vacuum baked them?

[belwar]

yeah they are nice and potted to the core, but not with wax, nor with the same black goop. I'm thinking its either bondable wire, or some form of laquer. I wonder if you could use an oven to bond the wire.. hmm

[David King]

They were vacuum baked.
Furnaces are used to fuse bondable wire.
Typically when AC motors are rewound they are dipped in a vat of varnish which is then baked for many hours until all the windings are fused together.
This varnish isn't like the wood coating varnish as it's all oil and resin without dryers or volatiles. It's the same stuff used to coat power transformers.

[Joe Gwinn]

Originally Posted by Sheldon Dingwall

I'd really like to know what the inner compound is. The outside IIRC was epoxy.

Joe, do you mean silicone rubber (I've never heard of silicon rubber)? If that's the case, how would you tell?

Yes. Burning will still yield sand.

I'm still looking for an RTV potting compound.

RTV is a silicone rubber. It's pretty easy to get, but one must go to a plastics supplier.

[Possum]

Micromark has RTV silicon mold stuff and any jewelry supply place will have the baking type and RTV, there are many kinds of the stuff. I used a see through silicone mold material that you baked so you could see when cutting the mold apart without damaging the wax model.

Lacquer makes a really crappy potting liquid, it doesn't penetrate more than a few layers deep, probably why Fender only used it a short period, plus on some insulations its like putting an expiration date on it because it will degrade the coating, I've rewound a fair amount of vintage Fender ones like that. It does have a unique tonal thing going though.

[David Schwab]

Fender still uses lacquer on the bass pickups.

I use vanish. I don't have a vacuum setup yet, but it does get all the way to the inside.

And vanish and plumbers tape work really well together.

[Joe Gwinn]

Originally Posted by David King

Typically when AC motors are rewound they are dipped in a vat of varnish which is then baked for many hours until all the windings are fused together. This varnish isn't like the wood coating varnish as it's all oil and resin without dryers or volatiles. It's the same stuff used to coat power transformers.

The traditional varnish for motor and transformer windings is Glyptal Home Page.

Motor windings are dipped and baked twice, to ensure that the windings are mechanically solid and so won't fret (and thus short) from vibration while running.

Transformers are usually dipped once, unless intended for severe vibration service, in which case they too may get the double dip. Small high-voltage transformers (such as TV flyback transformers) were sometimes double dipped as well, to eliminate all voids where corona discharges could happen.

Glyptal is and was also used as a threadlocker, long before loctite was invented. Glyptal is a dark red color, and you often seen fasteners in electronic equipment daubed with glyptal so they won't loosen in use.

GC sells Glyptal in small bottles for touch-up and repair.

[Possum]

You use "vanish?" Is this paint on stealth material? Did it? They still use lacquer on bass coils? On poly coils its probably not a problem, PE though are the dead ones I've seen too many of.

[Mike Sulzer]

Motors and power transformers are subject to high temperatures as well as vibration. The varnishes, etc., are designed for this type of environment. If pickups need to be potted, is the usual mixture of waxes not good enough?

[David Schwab]

Originally Posted by Mike Sulzer

If pickups need to be potted, is the usual mixture of waxes not good enough?

I don't want to deal with wax, and varnish works great.

Some pickups are potted in lacquer, and Rick Turner uses shellac, so I figured why not varnish?

[David King]

I think the issue here is that longer coils will see some significant stretching and shrinking due to ambient temp changes. If you encase the wires in something solid you have a higher probability of failure over time as the wire can no longer slide around a little as it reacts to temp changes.
Wax works but it clearly changes the tonality of the pickups in some cases according to folks around here. The question is whether there is a happy medium, a goop that's stiff enough to keep the sonic purists happy and gummy enough to keep the wire from breaking when the guitar spends 10 hours in the hold of a transatlantic flight at minus 20º and then gets warmed up to 105º at the other end of the trip...

[belwar]

Originally Posted by Joe Gwinn

Motor windings are dipped and baked twice, to ensure that the windings are mechanically solid and so won't fret (and thus short) from vibration while running.

That would explain why Lane baked the pickup twice..

Originally Posted by Joe Gwinn

Glyptal is and was also used as a threadlocker, long before loctite was invented. Glyptal is a dark red color, and you often seen fasteners in electronic equipment daubed with glyptal so they won't loosen in use.

GC sells Glyptal in small bottles for touch-up and repair.

The wire is relatively dark red. It looks like motor windings. It looks darker than standard polysol. Can you tell me what GC is ?

[David King]

SPN soderon is red. I'm pretty sure that's what this wire was. I doubt very much that any Glyptal was used in these pickups. That stuff makes a mess and stinks to high heaven. It's intended to penetrate larger wire gauges and fill the voids between them, much too thick to get through a 42 awg coil I bet.

Lane baked twice because the first bake solidified the windings and the second bake solidified the black epoxy shell. There were never any injection molded shells, too many shapes to recreate.

[Joe Gwinn]

Originally Posted by belwar

The wire is relatively dark red. It looks like motor windings. It looks darker than standard polysol. Can you tell me what GC is ?

GC is GC Electronics, a widely distributed distributor of chemicals for electronics.

This is not glyptal, but it's a varnish for another purpose: GC Electronics - 10-5002 - Allied Electronics

GC may no longer carry glyptal.

A call to the Glyptal Corp should yield a lead. Glyptal 1201 appears to be the original Glyptal.

[Possum]

If he was baking it for the coil then its obviously bondable wire. I wonder what temp that stuff fuses together. I think I had a Korean pickup I took apart once that was bondable and it was on a plastic bobbin so couldn't be too hot....

[David Schwab]

Originally Posted by David King

I think the issue here is that longer coils will see some significant stretching and shrinking due to ambient temp changes. If you encase the wires in something solid you have a higher probability of failure over time as the wire can no longer slide around a little as it reacts to temp changes.

Has that actually happened though? I have a Hi-A pickup I bought in 1976 and several very old EMGs and an even older Overlend EMG, and they all still work fine.

[David Schwab]

Originally Posted by Joe Gwinn

The traditional varnish for motor and transformer windings is Glyptal Home Page.

Wow, that's a truly dreadful website! They don't really tell you much of anything there.

Originally Posted by Joe Gwinn

This is not glyptal, but it's a varnish for another purpose: GC Electronics - 10-5002 - Allied Electronics

I've seen those varnishes before. A bit pricy, no?

[David King]

Possum,
I'm only going by the Bassics article referenced in the earlier thread, it makes no mention of bondable wire, only epoxy being sucked into the coil and then baked in a vacuum oven. That's not to say the article is factually correct but I'll bet that ordering bondable wire probably costs more. And since Lane was clearly conscious of his bottom line and since he'd already invested in the vacuum oven, I'm pretty sure he would want to use it whenever he could.

David,
I have seen many epoxy potted pickups go south, I think it has more to do with the winding tension than the epoxy used but Joe Guinn seems to imply above that a softer potting material might promote longevity in the coil.

I gathered up some more circumstantial evidence about the "bad batch" of LP pickups. At least one of them has the windings and magnets in phase so not hum-canceling at all.

[David Schwab]

Originally Posted by David King

I have seen many epoxy potted pickups go south, I think it has more to do with the winding tension than the epoxy used but Joe Guinn seems to imply above that a softer potting material might promote longevity in the coil.

It's not a bad idea.

One thing to notice here is the actual coils are encapsulated in regular epoxy. Then that cured assembly was encapsulated in the gummy stuff.

So that can't be the reason he did it that way. Maybe the other stuff was cheaper than the epoxy?

I gathered up some more circumstantial evidence about the "bad batch" of LP pickups. At least one of them has the windings and magnets in phase so not hum-canceling at all.

That's not good. I figured maybe some of them didn't have the shielding grounded.

[David King]

Originally Posted by belwar

yeah they are nice and potted to the core, but not with wax, nor with the same black goop. I'm thinking its either bondable wire, or some form of laquer. I wonder if you could use an oven to bond the wire.. hmm

David,
Thanks, I did miss that detail.
I'm wondering now if the rubbery layer was to reduce microphonic handling noise?
Epoxy is about the cheapest stuff out there that doesn't take long and doesn't shrink as it hardens (or stink like polyester.)

Maybe it is bondable wire after all? Anyone ever price that stuff?