nt2a circuit for repair

hi
someone send me rode nt2a for repair ...... noise problem :. rode used prefect  circuit in nt2a.

as we know nt2a is multi patterns.first transistor  is smd n channel j  fet . cod is 450 but no data in net .  best choice is j111 from on or sst111 from vishay .left leg is ...s...  if see 5 v  to 5.5 v in d of j fet ...meens this part of circuit is ok .most of time noise comes from caps .chang and clean  pcb after soldering . complementary feedback pair (CFP) by adding a PNP transistor in the drain circuit of jfet.rode make good sound for record by choice this  perfect circuit . some  n and p  transistor with jfet in frontend .feed back for reduce noise.

I'm not sure why you would call it "perfect circuit", however i do agree they make great microphones, way underrated.

Thanks for the schematic, but you could just try to contact them, they are often willing to replace the mics even years after warranty expiring.

in tubes  circuits  ... one tube and  one transformer  this is all...quality  of output  sound depend to  tube and transformer quality.
but in fet circuit we can use  more active parts .some of them  control the dc and some  make feedback circuit  for reduce noise .

rode  nt2a  is  simple but  clever    design.they used  jfet in classic way and  control this jfet with  3 transistor for stable result and low noise  .very simple and good hpf switch    nice class a amp in 22 v ..control for temperature  effect  in dc ....in output no transformer and simple xlr  .
rode company  in out of warranty should  repair  pcb by component level for customer.
or  replace  pcb.i don't know way they replace  mic  ? they need good technician

..isn't this pretty much like the later neumann tlm-series mics, impedance-balanced and all...?

Jakob E.

yes same in output xlr but different in some items .

Nice - thanks for sharing!

Jakob E.

Hi !!!, my name is charles, sorry to revive this tread, sorry about my english, i got a rode NT2a i found 4 bad capacitors y i need to find out the correct values of them, some one can help to me ? , i ve attached a pic of the board marking with a circle in red and green the caps that i want to replace, and i like to know the values y what tipe of smd cap are them. Tanks in advance.

Sorry, the problem of the mic is some cracling noise. y remove the caps market in green and red and cracling disapears, but now the is a constant wind noise, perhaps cos missing of theses caps ? tanks

I've had that problem too. I just replaced those with some 100nF / 100v capacitors and that cured the noise issues.

Khron said:

I've had that problem too. I just replaced those with some 100nF / 100v capacitors and that cured the noise issues.

Click to expand...

Thank you very much !!! fast response !!! a question what kind of cap did you use ? ceramic ? thanks in advance !!!

In the NT1 it is always the (SMD) capacitor for the polarisation voltage that fails.

charlygrand2013 said:

Thank you very much !!! fast response !!! a question what kind of cap did you use ? ceramic ? thanks in advance !!!

Click to expand...

Yes, ceramic - it's only filtering the tiniest of currents, with large-value resistors upstream of it, so there was no point in going with (physically much larger) film caps. And it's also kinda tight in there...

RuudNL said:

In the NT1 it is always the (SMD) capacitor for the polarisation voltage that fails.

Click to expand...

I still find it so odd that, ironically (?) enough, it's the FILM capacitor that fails, not the ceramic that's in parallel with it. Also odd that they parallelled the two kinds after the last series resistors...

Khron said:

Yes, ceramic - it's only filtering the tiniest of currents, with large-value resistors upstream of it, so there was no point in going with (physically much larger) film caps. And it's also kinda tight in there...



I still find it so odd that, ironically (?) enough, it's the FILM capacitor that fails, not the ceramic that's in parallel with it. Also odd that they parallelled the two kinds after the last series resistors...

Click to expand...

Do i have to use smd component of similar physical appearance or can i use through hole?
can i use this cap instead of those 4 smd capacitor?

btw i have windnoise problem

You'll want a voltage rating of at least 100V. If you decide to use through-hole capacitors there, it might not be a bad idea to also glue them down somehow, so the solder joints (or rather, the glue between the copper and fiberglass of the circuit board) are not the only things mechanically supporting them.

should i change all or one by one?

It depends how "paranoid" you are. But then again, the first film cap you desolder might not be the one that's failing.

Are you getting the noise in all three patterns?

yes

there is less noise in -10db
but there is still noise

Then it's quite likely at least the film cap on the positive bias rail (that's always connected to the front diaphragm) is to blame. That's the one nearest to the yellow capsule wire.

And as i mentioned in one of my earlier posts here, i replaced that film cap with a ceramic one (there's another ceramic one there from the factory anyway), and that made all my noise issues go away.