D87 no sound

[Greenie]

Hi. Sorry to bothe you all, but I just finished DS87 build, and the result was silence. I dind certai connections a bit confusing, that is first the connections of the AMi T13 transformer, and the 4 capsule wire. Any advise about that?

 

[Khron]

Maybe better to ask this in the build / support thread for that project?

https://groupdiy.com/threads/neumann-vintage-u87-clone-build-thread.48030

 

[Drosselmeier]

Hi. Sorry to bothe you all, but I just finished DS87 build, and the result was silence. I dind certai connections a bit confusing, that is first the connections of the AMi T13 transformer, and the 4 capsule wire. Any advise about that?

you need to take a multimeter, turn on the phantom 48v and start checking the circuit from XLR to JFET

 

[TLRT]

Or check with electrometer if the polarization voltage is there or not. I guess you could set your fet bias,so the problem should be in the high impedance section.

 

[Greenie]

The mic is just not working, just sends out noise. I am wondering if anyone good give some advice on the best way to check if sny part is afwlty. I get noise reacton on almost every part, I also get some voltage readings on ceratin part, 4.4v is several places. Being new to building mic. D87, I am in a bit of rut here?

 

[Greenie]

When I touch the blue markings on the bottom right, I get reaction when I touch them with the probe, the upper blue circle I get about 4.5 volts, and on the bottom left, where the transfore connects, I get votage reafdings around 38v on the two lowers each sent to ground? And the how to decide the primary and the secondary on the T13 transformer, is th hihest ohm, round 400, is the P?

 

[Greenie]

So now I am getting to the finish line with my second attempt on the U87 blue pcb version. I hasve the AMI T13 and I wonder (still) how to hook up the wires to the pcb labelled S+ S- and P+ P-?

 

[Ricardus]

You're still posting in the wrong thread.

So check the AMI docs and see what wires are Primary and Secondary (hence P and S), and see which ones they labeled + and - .

 

[Greenie]

The yellow pair measure 23R and the blacks 449R? The yellow seem to be secondary, but is there a negative and positive side?

 

[Khron]

https://www.tab-funkenwerk.org/product/t13/
Compare the drawing on that page, with the schematic of whatever you're trying to assemble.

 

[Drosselmeier]

The yellow pair measure 23R and the blacks 449R? The yellow seem to be secondary, but is there a negative and positive side?

black -> p+

black -> p-

yellow -> s+

yellow -> s-
adjust the phase of the signal after assembly

 

[Greenie]

Thanks a lot.