Neumann U87ai needs repair and testing

[Spencerleehorton]

ok, so im gonna change C102, C103 and C104 and see what happens.
after that i dont know what im gonna do!!!!

Spence.

 

[tubestation]

Spence,
I can understand your Frustration.
One more Though,
With the Headbasket removed, the female Plugs are still in the Chain, so If they  are polluted they could charge like a Capitor and discharge, causing the Pops.
Did You resolder all Solderjoints ?
I mean If You replaced almost every Part of the Board and You still have the same Trouble, it could be something else than a faulty electronic Part.
If You can t get it solved You  could,
Send the Mic to a good Mictechnician.
When You send the Mic to a standart Neumann Servicestation , They probably would refuse to fix the Board because of Your already done Soldering. They would replace the whole Board what could be a costy but maybee worth Solution. Or ask If they sell You a Replacementboard.
But I am really not sure anymore If it s the Board that makes the Trouble.
Did You replace the rotten K 87A Capsule with a original Replacement? Or did You install another single Backplate Replacement ? If so You could buy another Dual Backplate Capsule and install a new 87 Board from Danny. You could use the Neumann Outputtransformer.
You could send the rotten K 87A to a reskinn , (Maybee Tskguy can help) and build a U 67 out of the re- skinned Capsule and the rest of the Mic. Maybee with the same Cost at the Price of a Neumann Replacementboard.
Greatings
Lothar

 

[Spencerleehorton]

hi,

Yes i have another PCB from Dany here i just don't know if the owner wants that to happen but it seems the only good way forward to making this work properly. I have established its definitely not the capsule as the same sounds happen without the capsule connected.
when poking around at RT point there does seem to be some kind of problem here and i have cleaned and soldered on and re solder all joints but the sounds are there, they are down is level considerably so i know i'm close!!!

regards

Spence.

 

[tubestation]

Spence,
Nice to hear You come closer solving the Problem.
If You want to use Dany s U 87 Board a dual Backplate Capsule would be nessesary, no ?
If the original single Backplate ( the two Backplates are internaly connected, not isolated ) K 87 A  is ok, that s good news .
Greatings
Lothar

 

[tubestation]

Hello Spence,
Any Progress ?
Please keep us updated,
Thank s
Lothar

 

[Spencerleehorton]

No more progress sorry, I am waiting for the owner to make a decision on what to do with it.
As I have suggested gutting it and putting in the Danny U87.

My scope is in for repair so there nothing more I can do until it comes back.

Unless you have some more suggestions?

Regards

Spence.

 

[Pip]

Bite the bullet and send it to Neumann for restoration. It will keep the value intact.  Although it maybe to late as you have really gone through it. I ask once again can you send pic?

 

[Nyquist]

Stop stuffin around with it and send it to Sennheiser for repair

 

[Banzai]

You'll obliterate the value if you tamper with it, and you'll literally turn it into a doorstop if you install some random DIY board.

Don't forget it's a $3'000+ microphone .

As I have suggested gutting it and putting in the Danny U87.

 

[Spencerleehorton]

It's not my decision to send away as I've already stated, this is not my mic, someone had asked me to have a look and replace the capsule, when it still made the noises I thought I'd ask for help, as this problem seems to have stumped everyone!!!
If they make the decision to send it away I would be very happy, would be a shame to gut this mic but Dany's U87's sound so much better than this mic, would definitely be an improvement.

Spence.

 

[tubestation]

Hello Spence,
Don t make Yourself unhappy.
As many experienced People suggested it s  Time to send it to a  Prof. Micrepairlab or to give it back to the Owner.
If Sennheiser refuse to take the Job, try Drefahl Audio in Germany or ask Andreas Grosser If he can help or If he knows Somebody.
http://www.drefahlaudio.com/mic/1_cli.html
As said it s a very expensive Mic, You and some of us really tried our best to help . Difficult to Diagnose from the far Distance.
If You spoil the Mic, in the End You are responsible and You lose a Friend or a lot of Money.  i know what i am talking about, i once spoiled the Mastersection of a Desc, had a lot of Trouble to find Somebody who helped, i paid the Bill..... I also wanted only to help....
If You want to install a Dany 87 Board, don t forget You need a dual isolated Backplatecapsule like the K 670  to be able to generate all offered Pattern from  a single 48 V.  Another,a  4 Way  Switch is also nessesary in the Headbasket to switch all Pattern.
It s more easy to build a completly new Mic with the Board than the Implimentation into a U 87 ai.
The  Capsule in the U 87 ai  the K 87 a is a " single Backplate " . That s why a dc/dc Converter with the +/- 60 Volt is implemented in the 87 ai. As mentioned and discussed here, this was done to get some dB more Output  because now the Capsule can be biased with +/- 60 Volts, and more important , to reduce Straycapacity , this have been the Case with the isolated Dualbackplate K 87.
Greatings
Lothar

 

[Spencerleehorton]

Hi pip, yes I have checked the capsule and put it in another U87 and it works beautifully, the pins are fine as well, as I've said quite a few times the noises persist even without the head basket on.

Spence,

 

[Banzai]

As mentioned already, it's just important not to get carried away with this whole DIY thing. These  mics maintain market value, and there are a lot of people out there who will pay $2'000+ for a s/h U87Ai, however bad the sound is compared to this GDIY kit.

But once it's been gutted or modified, no-one will touch it.

Good luck with the repair though, and hope you find a solution!

It's not my decision to send away as I've already stated, this is not my mic, someone had asked me to have a look and replace the capsule, when it still made the noises I thought I'd ask for help, as this problem seems to have stumped everyone!!!
If they make the decision to send it away I would be very happy, would be a shame to gut this mic but Dany's U87's sound so much better than this mic, would definitely be an improvement.

Spence.

 

[tubestation]

Spence,
One last Thought.
You said a few Times that the Noise is present, even with the Headbasket removed.
After all Your Partreplacement i still wonder If it is a Malfunktion Part or a " mechanical " Problem.
There are still the female Parts of the Pins , inside the Plastikbase connected to the Circuit.and If they are corrodet  or humid, a discharge , causing Pops could happen  . Could You lift the 470 pF on the Side where it is connected to the female  Plug or If too tricky,  on the other Side, to take the female Plug 2 out of the Signal ?
Greatings
Lothar

Quote from Banzai :
"As mentioned already, it's just important not to get carried away with this whole DIY thing. These  mics maintain market value, and there are a lot of people out there who will pay $2'000+ for a s/h U87Ai, however bad the sound is compared to this GDIY kit."
But once it's been gutted or modified, no-one will touch it."

I agree but some People even don t hesitate to buy a brand new 87 ai to build a U 67 with it. Or to put a " inner Tube " inside.
So it s like always a Point of View or howmuch Risk or Money One is willing to risk. For some People a 87 ai is a kind of holy  Grail, dream about it  half  of there Life,  can t afford it.
For some People it s just a better Sm 58.....
I personally see it like You,
Lothar

 

[Spencerleehorton]

Well my final analysis is that the XLR plug was faulty and the actual slot that the lead goes in is too big and now Ive changed the 3 pin xlr plug the mic works fine as long as the xlr lead is taped in.
There must have be a number of factors why this mic had the problems it did but it now seems to work fine.
Sound wise my D-U87 sound much better in every way, which I'm glad I didn't go down the route of getting an original Neumann U87!
Thanks again for everyone's help.

Regards

Spence.

 

[Banzai]

What brand XLR cable connectors are you using?

Well my final analysis is that the XLR plug was faulty and the actual slot that the lead goes in is too big and now Ive changed the 3 pin xlr plug the mic works fine as long as the xlr lead is taped in.
There must have be a number of factors why this mic had the problems it did but it now seems to work fine.
Sound wise my D-U87 sound much better in every way, which I'm glad I didn't go down the route of getting an original Neumann U87!
Thanks again for everyone's help.

Regards

Spence.

 

[Spencerleehorton]

Have tried several neutrik and other types all are loose, as I said the bottom bell must have either been wrongly manufactured or has been misshaped as its too big.

Spence.

 

[Banzai]

Played around with a U87 today. Your mic is missing this part: http://spares.sennheiser.co.uk/neumann/tlm-103/neumann-u87-u87ai-xlr-locking-ring-070110.html

It sits in the bottom of the connector housing, and tightens the XLR connector's contact with the cable.

Have tried several neutrik and other types all are loose, as I said the bottom bell must have either been wrongly manufactured or has been misshaped as its too big.

Spence.