AKG C414 Problem

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colonel_sanders

Active member
Joined
May 24, 2010
Messages
43
Hey guys!

I took Gyraf's advice and replaced C8 as well as C9.  C8 was the problem and now the mic is working perfectly, and can go back to work :).

Thanks to everyone for their advice.  This forum is the greatest!!

:) :) :)

Cheers,
Arie
 

EvLoutonian

Well-known member
Joined
Jul 7, 2010
Messages
184
Hey Folks,

My friend just received a C414-EB from eBay, and it sounds like possibly the same issue.  VERY LOW OUTPUT LEVEL.

The seller said it was working when they dispatched it, but when my friend tested it, to me it sounds like the character of the signal is not terrible, but at 5% amplitude strength - like, TINY.

(I can post sound files if that helps?)

Anyway, he sent it to the Aussie service department (with the AKG distributor in Sydney) but it sounds to me like all they suggested is that they would replace either the two circuit boards, or the capsule, to see which is faulty!

(except that they no longer have stock of either components)

What ever happened to servicing at a component level!! (?)

Should I suggest to the tech that he looks at the equivalent capacitors, as mentioned here with regards the ULS version?

MANY THANKS!
Evan
 

mjrippe

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Dec 27, 2011
Messages
2,575
Location
Brooklyn, NY
Yes, you could certainly replace any electrolytics in a mic of this vintage without a second thought.  Check the tantalums because they can fail shorted.
 

Jellybelly

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Aug 20, 2021
Messages
21
Location
London
Thanks in advance for any suggestions.

i am wondering how to check the tantalums? What settings are required, and equipment? Can it be done on a multimeter or is a cap tester needed?

Also for c8 and c9 are there new old stock or equivalent exact spec capacitors available to purchase?

Thank you so much
 

gyraf

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Aarhus, Denmark
You really can't check them in-circuit and expect correct reading

I would just replace on suspicion, and if that fixes it, it was proven to be problematic

You don't want NOS for tantalum caps, just get good-quality modern ones. Long-life if you can find such.

/Jakob E.
 

Jellybelly

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Joined
Aug 20, 2021
Messages
21
Location
London
You really can't check them in-circuit and expect correct reading

I would just replace on suspicion, and if that fixes it, it was proven to be problematic

You don't want NOS for tantalum caps, just get good-quality modern ones. Long-life if you can find such.

/Jakob E.
Thank you for your post.

I have a signal drop and also the low motorboating sound. It's intermittent and not the diaphragm as far as I can see. It sometimes oscillates and squeaks on the high frequency. There is a sound level drop that is quite noticeable. It can be rectified with a polar pattern switch.

I tried a few dabs of caig deoxit and it seemed to quieten down for a while. I haven't tried deoxit on the pad and low cut yet.
 

Zim

Active member
Joined
Feb 18, 2020
Messages
36
You really can't check them in-circuit and expect correct reading

I would just replace on suspicion, and if that fixes it, it was proven to be problematic

You don't want NOS for tantalum caps, just get good-quality modern ones. Long-life if you can find such.

/Jakob E.

Can you use an ESR meter to check them in-circuit?
 

Jellybelly

Member
Joined
Aug 20, 2021
Messages
21
Location
London
You really can't check them in-circuit and expect correct reading

I would just replace on suspicion, and if that fixes it, it was proven to be problematic

You don't want NOS for tantalum caps, just get good-quality modern ones. Long-life if you can find such.

/Jakob E.
Thank you for your post.

I have a signal drop and also the low motorboating sound. It's intermittent and not the diaphragm as far as I can see. It sometimes oscillates and squeaks on the high frequency. There is a sound level drop that is quite noticeable. It can be rectified with a polar pattern switch.

I tried a few dabs of deoxit on the polar pattern switch and it seemed to quieten down for a while. I haven't tried deoxit on the pad and low cut yet.
 
Joined
Jun 15, 2010
Messages
14
Hey Folks,

My friend just received a C414-EB from eBay, and it sounds like possibly the same issue. VERY LOW OUTPUT LEVEL.

The seller said it was working when they dispatched it, but when my friend tested it, to me it sounds like the character of the signal is not terrible, but at 5% amplitude strength - like, TINY.

(I can post sound files if that helps?)

Anyway, he sent it to the Aussie service department (with the AKG distributor in Sydney) but it sounds to me like all they suggested is that they would replace either the two circuit boards, or the capsule, to see which is faulty!

(except that they no longer have stock of either components)

What ever happened to servicing at a component level!! (?)

Should I suggest to the tech that he looks at the equivalent capacitors, as mentioned here with regards the ULS version?

MANY THANKS!
Evan
This mic also contains a DC to DC converter (the board with the round transformer on it) to bias the capsule. You might want to check to see if it's doing its job.
 

Jellybelly

Member
Joined
Aug 20, 2021
Messages
21
Location
London
Aside from a vocal test, when I move the polar pattern switch it cancels the buzzing and bumping sounds and seems OK again. However it sometimes sustains a 14dB drop for a while at times.
 

Jellybelly

Member
Joined
Aug 20, 2021
Messages
21
Location
London
This mic also contains a DC to DC converter (the board with the round transformer on it) to bias the capsule. You might want to check to see if it's doing its job.
Can anyone recommend a decent multimeter that's reasonably priced, with a link to ebay in private message because I can't seem to find my one. Thank you so much!
 

Jellybelly

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Joined
Aug 20, 2021
Messages
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Location
London
I'm going to order a full set of caps, can anyone help with a shopping list and links to a good store in the UK?

I will look for any bad solder joints, loose wires, bulging caps, then replace the two foil caps, and keep replacing from there.
 

Khron

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Apr 8, 2010
Messages
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Location
Finland
Aside from a vocal test, when I move the polar pattern switch it cancels the buzzing and bumping sounds and seems OK again. However it sometimes sustains a 14dB drop for a while at times.

My memory might be failing me, but i was under the impression that the switches in these mics were infamous (?) for failing in time.
 

Jellybelly

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Aug 20, 2021
Messages
21
Location
London
Also I read that the cover that cracks either side, establishes a Faraday cage field effect and if it is not connected properly, it can cause buzzing and hums. And guess what? Both my mics are cracked either side of the frame with the microphone mesh... 🤔 😳
 

Khron

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Joined
Apr 8, 2010
Messages
1,937
Location
Finland
Also I read that the cover that cracks either side, establishes a Faraday cage field effect and if it is not connected properly, it can cause buzzing and hums. And guess what? Both my mics are cracked either side of the frame with the microphone mesh... 🤔 😳

If anything, that would DETRACT from the effectiveness of the Faraday cage that the headbasket and body form around the capsule. No idea what a/the "Faraday cage field effect" might be, though.
 

Jellybelly

Member
Joined
Aug 20, 2021
Messages
21
Location
London
If anything, that would DETRACT from the effectiveness of the Faraday cage that the headbasket and body form around the capsule. No idea what a/the "Faraday cage field effect" might be, though.
I will gladly dismiss that notion that was proposed on a forum post, people were discussing soldering cables to ground the capsule as well.. Maybe I missed the irony.
 
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