Scored lines on speaker voice coil former

Something isnt right here. Are the scored lines on the inside or the outside of the coil former? Are the windings damaged by the scoring? If it were the setting shims to blame for the scored lines - which seems doubtful they`d use metal, all mine are plastic - they go on the inside of the coil former. The windings are on the outside.

Take photo if you can.

Ron(UK)

phenolic

pair

end

being

the lines are on the smooth internal surface that glides over the central section of the magnet, not the coil surface.

I doubt the lines are anything to do with the failure, that is well outside the coil area. Probably due to stress on epoxy curing on a supposed stress relieving bend of the coil runout wire inside a fillet ring of epoxy where the cone meets the phenolic cylinder and before the join with the pigtail, so repairable.

Will try a pic of the lines

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

phenolic

pair

end

being

There is no overheating , scoring or any damage to the coil or elesewhere just these lines.

Could someone confirm that the woven and corrugated yellow part I've labelled purple "S" is called the spider. The cone is to the other side of it. "L" is the lead out of the coil and "G" is some sort of optical guide laid in the layup, on the manderel, of the phenolic for placing the lead-outs to then meet up with the pigtails at the cone. Moire fringing is where the coil is. A second sight guide and second of a pair score line is part in shadow off to the upper right.

There is a third and fourth pair of lines diametrically opposite these 2 pairs

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Yes the rear suspension is traditionally refered to as the spider because in early speakers it was a (usually) three legged tufnol affair a bit like the '3 legs of Man' mounted insided the v/c and screwed to the pole piece of the magnet. The v/c was centered by loosening off the screw and moving the spider around. Often a low frequency (100 hz) (120 in the USA) note was played through the speaker whilst the adjustment took place

I dont think that line G is any form of optical sight, just where the layup of the laminations of the former are recessed to feed the lower coil leadout up

I think those are just marks made by withdrawing the coil former from whatever chuck held it in the winding machine or curing oven - or both.

If there`s no rubbing or burning of the coil, you`ll probably find the o/c is where the end of the coil passes throught the cone and is soldered to the pigtail. This is sometimes repairable by scraping off the glue and reheating the 'blob'. Not worth messing around tho, replacement speakers like those are cheap.

Ron

How much time do you waste inflating customers' bills by wasting time on the pointless ?

Graham

Graham,

Since you've discovered this group, you've done just as little to contribute as you do on any other. Why don't you just go to bed...and stay there?

jak

one

seems

elesewhere

of

laid

to

coil

shadow

If it was scoring from expandable/contractable mandrel or a chuck of some sort I'd expect it to be engineered and pairs of lines exactly 6mm or something precise apart, these are about 6 to 8 mm apart and some lines have a nearby accompanying line. They are white as in scoring not grooves set in at moulding . Or more likely no marks as what is the point if the process leaves such serious imperfections where you don't want them.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

I don't know what else it could be then, if it were damage which occured in use, the lines wouldn't be so precise -a small amount of metal or grit in the magnetic gap makes a mess. It looks to me as thought the coil former has been slid off some kind of holder which has left marks where the contact points were. Are they such 'serious inmperfections'? you might possibly find every single speaker of that model has the same marks, and I doubt that they affect the performance of what is in reality a cheap speaker.

The whole exercise is academic anyway, it`s a ten quid speaker which almost certainly failed because of some other defect - probably customer misuse.

I suggest Mr Cook that you are a frustrated forensic pathologist - you obviously take great pleasure in taking things apart and performing autopsies,

;)

On Tue, 27 Jan 2009 16:56:04 -0000, "N_Cook" put finger to keyboard and composed:

I've often encountered speakers which sound distorted but are still functional. By moving the cone by hand, I can feel and hear the coil scraping against something. Would this be caused by blistered insulation as a consequence of overheating?

- Franc Zabkar

--
Please remove one \'i\' from my address when replying by email.

Any bits of swarf or grit, causing lines in service, would be only half the length of these lines. They extend the whole axial length of the coil former, into the dome space.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

There was a cartoon drawn with a drooling idiot who was called 'Skippy'

--
You can\'t have a sense of humor, if you have no sense!

Speaking of Eeyore (aka Graham Stevenson) I haven't seen him online for months, any one heard anything from him?

Ron(UK)