Re: Microphone Oktava 219A stopped working
Thank you guys!
Will simple ethyl alcohol 96% work?
Does it mean I can use 3-leg JFET and dismiss connecting ground? If the only reason of ground connection is shielding, that modern JFETs doesn't require....
skunks
Member
Last Activity: 10-17-2015, 08:35 AM
Joined: 12-17-2014
Location: Chernihiv
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Re: Microphone Oktava 219A stopped working
The quest if over! The mic is working now.
Thank you once again, Khron and all the guys who shared their thoughts to help me.
All 4 electrolytic caps were bought yesterday on local market. And today I started to replace them. First of all I replaced C9 (once again:-D) and C7. And it helped! Then I replaced other 2 caps just for the case.
BTW, when I turned my mic ON without the case (which acts as a shield) there was a VERY loud hum (50Hz I suppose), much louder then my voice. Though I didn't touch ground...Leave a comment:
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Re: Microphone Oktava 219A stopped working
Thank you for your help, Khron666. I really appreciate that.
I thought that those 2 little things you marked as R1 and R2 are condensers
. I've measured it's impedance - it's more then 2000k Ohms, article proves they has to be that big (1000M (1G) resistor).
Saying this - I must admit that you were right point me to this schematics:
[url]http://www.sdiy.org/oid/mics/Oktava-MK219.gif[/url]
Here are 2 more photos - one of them with back light in order to see traces (and all 4 legs...Leave a comment:
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Re: Microphone Oktava 219A stopped working
Khron666, you are right, I can put an effort and draw schematics. But I'm not too much experienced in electronics to know what this 4-leg JFET(?) is. It is "7БК8" written on it, but googling for "7БК8" didn't help. The scheme you guessed unfortunately isn't this either (mine has 8 resistors, 11 condensers (4 of them electrolytic), point 4 is connected not to the ground but somewhere else, my FET has 4 legs). Maybe because my mic is called "Oktava MK-219A", not "Oktava MK-219"....Leave a comment:
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Re: Microphone Oktava 219A stopped working
So, should I try to change that JFET also?
"Replace the FET with a Toshiba 2SK170BL" as suggested in article (from 1st reply made to this thread)?
BTW original jfet has 4 legs, "Toshiba 2SK170BL" has 3 legs.
I cannot fully proceed with mod described in article because
1. lack of experience in such things
2. the schematics differ
so I'd like to proceed with some kind of newbie non-destructive repairing.Last edited by skunks; 09-19-2015, 11:51 AM.Leave a comment:
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Re: Microphone Oktava 219A stopped working
Khron666, thank you for direction. However this schematic is different because number of resistors and condensers differ.
I measured voltages:
1.7v instead of 6.8v on C3 (47uF).
3.4v and 0v on FET instead of 2.1v and 22v.
Because schematics differ I could not find point of 0.8v to measure.
So, that's all what we have now.
The resistance of capsule is more then 2000k.
Transformer's resistance is
~760 Ohm on primary winding
8 Ohm + 8 Ohm ~= 15.4...Leave a comment:
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Microphone Oktava 219A stopped working
Yesterday I turned on my condenser mic Oktava 219A, but there was no sound. This mic served me from ~2001. It was a surprise for me.
I disassembled it. One of 1uF caps looked a little bit like extra fat, so I replaced it, but it didn't help.
Please could you advice my next steps.
May be buy and replace all the caps?... -
Re: New Members - please post your introductions here
Hello! I've found a topic in this forum with the same problem as mine, however it was not solved. Maybe this time?Leave a comment:
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