Repairing a Rode NT1

[letterbeacon]

I've been given a broken Rode NT1 microphone (I haven't had a chance to plug it in yet so I don't know what's wrong with it) and I want to try and fix it.  Has anyone got the schematic at all?  I couldn't find any Googling or using the search on this forum.

Thanks a lot!

 

[Gus]

Older NT1 look for the MXL2001 V67 etc circuit.

It is an easy circuit to trace and repair.

 

[letterbeacon]

Great thanks for that!  Unfortunately I can't seem to find schematics for that mic either!  I don't suppose you have a link at all?  Sorry, I'm not usually this rubbish at finding stuff!

Is the NT1 and the MXL2001 that similar that I can repair an NT1 using a MXL schemo?

 

[Gus]

IIRC the older grey one had a Jfet and  PNP and an output transformer?

Flatpicker drew a nice schematic of the 2001 IIRC.

 

[zebra50]

Here you go...

it's a bit big, i'm afraid

 

[letterbeacon]

That's brilliant - thank you very much!

How come I able to use this schematic despite it being for a different mic?  Are they the same circuits or just closely related?

 

[Gus]

Open up the NT1 and post some pictures or describe what you see.  Do you see a 170 and a PNP transistor on the PCB?

 

[letterbeacon]

Here are some pictures of the mic opened up.  The transistor marked Q4 near the bottom of the mic is a C2547 but I can't find any info on it - is that the PNP?

 

[letterbeacon]

Here's another pic of the insides...

 

[mad.ax]

The transistor marked Q4 near the bottom of the mic is a C2547 but I can't find any info on it - is that the PNP?

Most likely a 2SC2547...
Which is a NPN...

Axel

 

[Gus]

Look for the china microphone schematic based off the Schoeps schematic.  Q4 is most likely in the DC to DC converter section.

The other two T092s should be PNPs more in the middle and the top should be the Jfet.

Power it up with phantom and measure the pins of the transistors that will give you a possible clue what is wrong

 

[Rossi]

First of all, power it up with the complete mic body and see if it *really* doesn't work. Quite a number of mics given to me as defective were in fact fine. If it doesen't work, try to find out what exactly it is that doesn't work.

Always check for bad connections and ripped off leads first. In particular, check the XLR connector leads.

As Gus said, this circuit is based on the Schoeps circuit so forget the schematic posted above and look for the Schoeps schematic and/or the MXL 603 schematic (which is a simplified version of the Schoeps circuit).

The JFET (Q1) near the capsule works as a phase splitter. Q2 and Q3 are emitter followers for each leg of the phase splitter.

Q4 is part of the voltage converter circuit, which isn't part of the audio circuit, really, but produces a around 60V for capsule polarization. This DC-DC-Converter has very low current capabilities, so you probably won't read 60V on your meter, as your meter will load it down somewhat.

 

[letterbeacon]

Brilliant, thanks very much for the replies guys!

I'm completely snowed under at work so I haven't had a chance to plug it in yet, but I will do hopefully tonight.

Embarrassingly I can't find the Schoeps schematic anywhere either!  Is there a schematic archive anywhere that I should be consulting?  I've tried Google, the search function on this forum and on other forums to no avail!

 

[moamps]

.... I can't find the Schoeps schematic anywhere either!  Is there a schematic archive anywhere that I should be consulting?

Hi,
did you check zebra50's site?
Regards,
Milan

 

[zebra50]

Loads of stuff here on our website, just dig around. We're always adding more as stuff comes in.

http://www.xaudia.co.uk/

http://www.xaudia.com/xaudia/Schematics/Schematics.html


Also

http://www.gyraf.dk/schematics/schematics.html

and loads of stuff here...

http://www.sdiy.org/oid/mics.html

 

[letterbeacon]

Wow, loads of great stuff on that site - thanks Zebra!

I finally got a chance to plug it in and... it seems to work just fine!

Thanks everyone for posting!

 

[WolfHamburgGermany]

First of all, power it up with the complete mic body and see if it *really* doesn't work. Quite a number of mics given to me as defective were in fact fine. If it doesen't work, try to find out what exactly it is that doesn't work.

Always check for bad connections and ripped off leads first. In particular, check the XLR connector leads.

As Gus said, this circuit is based on the Schoeps circuit so forget the schematic posted above and look for the Schoeps schematic and/or the MXL 603 schematic (which is a simplified version of the Schoeps circuit).

The JFET (Q1) near the capsule works as a phase splitter. Q2 and Q3 are emitter followers for each leg of the phase splitter.

Q4 is part of the voltage converter circuit, which isn't part of the audio circuit, really, but produces a around 60V for capsule polarization. This DC-DC-Converter has very low current capabilities, so you probably won't read 60V on your meter, as your meter will load it down somewhat.

Thank you, I changed the XLR Cable and my NT 1 is working again. It really was the Cable. Before changing it always run for a few seconds. Mysterious. Regard from Hamburg Germany

 

[Monts42]

Thank you, I changed the XLR Cable and my NT 1 is working again. It really was the Cable. Before changing it always run for a few seconds. Mysterious. Regard from Hamburg Germany

I've recently been given a broken NT1 with a similar issue to this, where it will work for a second or two after plugging in. After that the signal level drops ridiculously low - with 60dB of gain the signal is barely audible above the noise floor, even with me screaming into the mic.
I've tried changing the XLR cable which didn't help...
I've taken the case off and examined the connections and everything seems fine. I've reached the conclusion that it's either the capsule or one of the components has died...
Does anyone have any suggestions on what to test or replace?
Thanks,
M

 

[Khron]

The first commandment of troubleshooting: Thou shalt measure voltages...