[johnzm]

picked up this pair of SMG-a for cheap... for a reason.. haha!
anyways i expected problems, but i did not expect what i found. it seems there is no green at all, and in general the tweeters looked nice (i think). i measured both tweeters and got about 4 ohms (i measured from the solder joints that had the 2 ends of the tweeter wire going in, is that right?) so i think they are ok. any comments on them would be appreciated.
my main issue is that one of the speakers has a huge separation between the bass wire and the mylar right down the middle. check out the fourth and sixth pic. if you hit the zoom after the link you can see in high res how badly the wire has separated. anyways i have read enough to know that fixing the ends of the wires is not terribly time consuming, and i am prepared to do that (using DAP from what ive read will be the best way) but this issue in the middle of the planar i was not expecting to see that.
does anyone have any thoughts on repair? also the black plastic piece that the wires run under is in the way of the repair. how does that come off?

[SteveFord]

Has the wire simply come adrift or is there damage to the wire itself?

[medium jim]

My concern is the color being a rusty red, that is indicative of wire decay.  You want to see light green. 

Is there any white pitting to the aluminum wiring?

Jim

[johnzm]

bass wire actually just came off like that! no damage and the speaker makes noise, but obviously some of the noise it makes is not good! i am hoping someone here will be able to give me some good ideas on getting it stuck back down without having to re run the whole thing.

the tweeter wires looked PERFECT, but i did not inspect every inch. i also have read that red means corrosion. if they look perfect is there any way to deter the corrosion? 

[medium jim]

John:

The best advice I can give you is to call Magnepan as they are very helpful and sell repair supplies that includes the glue and will provide free instructions on how to do the repairs. 

The hard part is already been done, getting to the panels.

A lot depends on how much delamination there is as to if you need to strip and redo the wires.  Typically if you have less than 25% delamination you can prep and reglue.

Jim

[johnzm]

John:

The best advice I can give you is to call Magnepan as they are very helpful and sell repair supplies that includes the glue and will provide free instructions on how to do the repairs. 

The hard part is already been done, getting to the panels.

A lot depends on how much delamination there is as to if you need to strip and redo the wires.  Typically if you have less than 25% delamination you can prep and reglue.

Jim

have you heard about using DAP instead of the super 77 adhesive? also i understand magnepan sells the kits to re do tweeters and bass wiring, but i am trying to avoid re doing the bass wiring. do you think it will be possible to use DAP on the ones that are loose mid panel? or am i probably going to have to scrap the whole thing and start over?

also, if you noticed anything in the pictures indicating a tweeter wire corrosion let me know.

[medium jim]

I used DAP to repair some mid panel delamination, as well as, some banana peeling at the ends.  The key is to prep the affected area to remove any old glue and to create a good surface on the Mylar.

Don't use the brush in the cap, rather small brushes to paint the dap on the underside of the wire(s).  And a slightly larger one to paint the top side.  Keep the brushes wet with acetone to thin the dap for easier flow.  It will evaporate and not effect the dap.

It takes about 10 to 20 minutes for the dap to set, during that time, you want to make sure that the wires haven't relifted. Press back into place if they have.

Work in small sections and use as little dap as necessary to get the job done. Wait 24 hours before hooking them up to be safe and testing them.

Jim

[johnzm]

terrific. now, about the black plug on the mylar. looks like a few of the wires im going to have to glue back down run under it. does that sucker lift right off or do i need to feed the wire back under it and between it and the mylar?

[medium jim]

Those are the tone rings, do not try and remove them!  Apply the DAP to the underside of the wire and then manipulate them back under the tone rings.  Let them cure for about 30 minutes, more if you can and then glue the wires down on the periphery.

Jim

[johnzm]

you have been a great help. one lsat question!

is the DAP also removable with acetone?

[medium jim]

I haven't tried, but I suppose acetone would enable you to remove the DAP.

Jim

[josh358]

I haven't tried, but I suppose acetone would enable you to remove the DAP.

Jim

Sounds like it would be worth testing first, because one day, the panels will require a complete rebuild and then it will be necessary to strip them bare without damaging the Mylar.

[medium jim]

Sounds like it would be worth testing first, because one day, the panels will require a complete rebuild and then it will be necessary to strip them bare without damaging the Mylar.

If they get to the point of a complete rebuild, new Mylar would be advised and you would basically have new panels.  The new Mylar isn't that expensive to make it cost prohibitive.

Jim

[josh358]

I don't know under which conditions they advise replacing the Mylar (other than the obvious, such as a tear). But those on a budget may choose to do the rebuild themselves, and that means old Mylar. Also, do they always replace the Mylar? I've never asked but it seems to me someone said somewhere that they do it only when necessary.

[medium jim]

I don't know under which conditions they advise replacing the Mylar (other than the obvious, such as a tear). But those on a budget may choose to do the rebuild themselves, and that means old Mylar. Also, do they always replace the Mylar? I've never asked but it seems to me someone said somewhere that they do it only when necessary.

Josh:

Probably true...I will have the mylar on mine replaced if and when they go back for a rebuild.

Jim

[josh358]

I may have to have one of my drivers rebuilt from scratch, since Fedex dented the pole piece with a fork lift. Apparently they have a tool that they can try first to see if they can undent it. But I'm not even sure what condition they're in, I bought them assuming they'd need a rebuild but haven't yet listened or taken the socks off. I'm building my new HTPC right now, so I should have a source in a week or so, but then I have to try something else in there first so it's still going to be a few weeks (it's been a few weeks away for a year now, LOL).

[neolith]

I think that the measurement of 4 ohms may be somewhat fortuitous and the fuses are blown. You can check the fuses with your meter. The reason for this is that with intact fuses the 15 ohm resistor is bypassed and the tweeter then lies in parallel with the inductor and your measurement should be <0.5 ohm, the approximate DCR of the inductor.  With a blown fuse the 15 ohm resistor is in series with the inductor and the total resistance (15.5 ohms) is in parallel with the tweeter - the impedance calculates to ~4 ohms.
In any case it would appear that the tweeters are intact.

[tberd]

 I'd replace the mylar and wiring. The wire kit from Magnepan is cheap. Throw in some Sonic Caps or Obbligatos for a cheap upgrade. Replace the internal hook up wires with some CAT 5 braids. Throw any fuse holders in the garbage if yours has them.

 I have a question. Anyone replace the mylar at home? How do you know how much to stretch it? Wiring seems straight forward with Dap.

tberd

[josh358]

I wouldn't try to replace the Mylar at home. If you don't get the tension right, the resonances won't be in the right place and the freq response will be off. However, that's me, some have done it successfully. Assuming Magnepan will supply it (it has to be the right thickness), you can find out how to tension it in DIY electrostatic articles. Measure the tension on an existing working panel of the same model first.