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Author Topic: Nakamichi CM-300 - No Sound / Low Sound HELP?  (Read 210 times)

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Offline spaceman.project

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Nakamichi CM-300 - No Sound / Low Sound HELP?
« on: September 06, 2018, 12:09:45 PM »
I picked up a set of CM-300's about a year ago.  I have been using them pretty regularly and found recently that one of the mics is producing very low output (more than normal) so I swapped out for the spare mic which is completely dead.  I get a pop when I flip it on, but nothing aside from that.  The 3rd mic is perfect. I have used all of them at some point in time in the last year. 

 - The attenuators are all turned to 0. 
 - I've swapped heads / capsules / batteries / cables / recording devices with no luck
 - It appears to be an issue with the bodies

What did I do to these?  Just curious if this ever happened to any of you and if I am missing something obvious?... 

any other tests you recommend for troubleshooting?

Thanks for the help!
« Last Edit: September 06, 2018, 02:21:08 PM by spaceman.project »

Offline kuba e

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Re: Nakamichi CM-300 - No Sound / Low Sound HELP?
« Reply #1 on: September 06, 2018, 02:14:33 PM »
If the body is faulty - try to clean XLR output, check switcher and look at battery connections (springs).

If the barrels and caps are ok, you can modify barrels to work without body. You will lose balanced output and you will need battery box. The advantage is that you get rid of an internal battery, you have a smaller microphone and you will have about 12 db stronger signal. Someone here is doing this mod. Unfortunately I do not know his name. Or if you can solder, let me know i will find schematic and you can do it yourself.
I made this mod on one of my Naks. Unfortunately I have not tested it yet. When it works, I'll do the other, then I'll send pictures. But it will take me a long time.
« Last Edit: September 06, 2018, 02:20:12 PM by kuba e »

Offline spaceman.project

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Re: Nakamichi CM-300 - No Sound / Low Sound HELP?
« Reply #2 on: September 07, 2018, 06:37:25 PM »
thanks for the response.  I cracked them open, saw that the dead one's spring solder joint had broken, so that was an easy enough fix, but it is still quiet.  It actually matches the level of the other quiet mic.  I cleaned them as much as possible, but didn't change the level.  Not sure what is going on here.  Are there certain components that need to be replaced over time?  I have done my fair share of recapping vintage audio gear, but never messed with microphones. 

I like how easy these mics are and the low noise floor, so would prefer not to mod them, but maybe will reconsider for another day.  I am recording on Monday, so was hoping for a "simple fix."  I will end up doing a matrix w/ AT-853's and hopefully get something good out of it.

Thanks!

Offline kuba e

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Re: Nakamichi CM-300 - No Sound / Low Sound HELP?
« Reply #3 on: September 10, 2018, 05:47:13 AM »
I have not heard of any component of Naks that would have to be replaced over time. But surely somebody could identify the components they can fail over time. Unfortunately, I do not know the electronics. Maybe you can try to measure the electronics and compare it to the schematic. The only thing I know is that the backplate charge in the microphone capsule is going down over time. But nothing can be done with that.

I wish you to discover the failure quickly.

 

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