Beyerdynamic M88N (c)

[totoxraymond]

Hi everyone!

I was given this old beaten m88N a while ago and now I'm trying to restore it to good shape (hopefully).



Well, this mic had better day obviously and unfortunately we get nothing out of it.

So I opened this little fellow which isn't too complicated though it seems some version are glued together and might be a bit harder.
This Particular one only needs unscrewing the different parts and the capsule slides out gently.



Here the capsule itself, nothing else inside the mic body.



It seems that there are 2 coils.
The first one is located on the inside which I think is glued to the diaphragm. I measured 190 Ohms.

The second one is wound around the capsule, and is wired in series with the first one. Unfortunately it measures open.

So i guess I found the fault. This coil needs to be rewound and it is here that the challenge starts.

I've never rewound a coil before and I could really use some guidance from the experts out here.

I think my best move from now on is to unwind this coil and count how many turns, then wind it back.

For that, i will need some wire. How do i now which size? This is really thin although the inner coil is even thinner.

Also, there is some tape around the coil, which is the best tape for this application?

If anybody has any clue or tips to give i would be very thankful.


Cheers,

Thomas

 

[panman]

Hi everyone!

I was given this old beaten m88N a while ago and now I'm trying to restore it to good shape (hopefully).

View attachment 101759

Well, this mic had better day obviously and unfortunately we get nothing out of it.

So I opened this little fellow which isn't too complicated though it seems some version are glued together and might be a bit harder.
This Particular one only needs unscrewing the different parts and the capsule slides out gently.

View attachment 101762

Here the capsule itself, nothing else inside the mic body.

View attachment 101761View attachment 101760

It seems that there are 2 coils.
The first one is located on the inside which I think is glued to the diaphragm. I measured 190 Ohms.

The second one is wound around the capsule, and is wired in series with the first one. Unfortunately it measures open.

So i guess I found the fault. This coil needs to be rewound and it is here that the challenge starts.

I've never rewound a coil before and I could really use some guidance from the experts out here.

I think my best move from now on is to unwind this coil and count how many turns, then wind it back.

For that, i will need some wire. How do i now which size? This is really thin although the inner coil is even thinner.

Also, there is some tape around the coil, which is the best tape for this application?

If anybody has any clue or tips to give i would be very thankful.


Cheers,

Thomas

That is the humbucking-coil you want to rewind. The wire size is not important. What matters is the number of turns, but even there give or take +/-one turn makes no real difference. The tape is just for protection, so any thin tape will do. Make sure to wind the correct original direction! Good luck!

 

[Tubetec]

Id search for the break in the coil , then carefully unwind the broken ends of the wire half a turn , trim , twist together , solder and then add new layer of tape around the coil to secure it, thats a lot easier than having to rewind it .

Theres a ding somewhere on that coil , look at it under a magnifier to help spot it ,
When you unwind it have some small strips of tape ready to prevent the coil unraveling . Use the multimeter to
confirm you have continuity to either end of the coil.

To strip the insulation from the magnet wire hold it for a moment near the blue part of the flame from a cigarette lighter or small butane torch , dont allow the wire glow red hot or it will oxidise , just heat it enough so the insulation melts , now use very fine 1000 grit emmory paper to clean the wire before twisting togther with the other and soldering.

 

[panman]

Id search for the break in the coil , then carefully unwind the broken ends of the wire half a turn , trim , twist together , solder and then add new layer of tape around the coil to secure it, thats a lot easier than having to rewind it .

Theres a ding somewhere on that coil , look at it under a magnifier to help spot it ,
When you unwind it have some small strips of tape ready to prevent the coil unraveling . Use the multimeter to
confirm you have continuity to either end of the coil.

To strip the insulation from the magnet wire hold it for a moment near the blue part of the fame from a cigarette lighter or small butane torch , dont allow the wire glow red hot or it will oxidise , just heat it enough so the insulation melts , now use very fine 1000 grit emmory paper to clean the wire before twisting togther with the other and soldering.

Yes, better try this first!

 

[totoxraymond]

Thanks you guys for those tips,

I'll have some time in the coming week to try this out.

I'll keep you updated!

Thomas

 

[hop.sing]

Since I have a broken m88 here also, I would love to hear if you could repair it somehow?

 

[totoxraymond]

Well, not yet...

Life got in the way, more important things to repair....

Also i need a magnifier fir this repair. I will certainly attempt to repair it though.

Thomas

 

[frans]

Polar audio from the UK had spare parts for that, if i remember it right.