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Post by indiehouse on Nov 1, 2016 7:58:44 GMT -6
I picked up a cheap MK-219 to tinker with modding, but I'm getting a really low output and a high noise floor. I haven't done anything to the mic yet. Anyone have any ideas?
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Post by kcatthedog on Nov 1, 2016 8:02:56 GMT -6
Does it have an on board tube ?
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Post by kcatthedog on Nov 1, 2016 8:04:32 GMT -6
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Post by svart on Nov 1, 2016 8:19:23 GMT -6
Go through the mic and resolder all the connections first. Oktava mics never had good soldering and are prone to broken solder joints, especially around the wires to the XLR.
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Post by indiehouse on Nov 1, 2016 8:29:01 GMT -6
Does it sound like a transformer or capsule issue to you? Those would be the 2 big ones that I don't wanna mess with. I'd rather not sink a bunch of money into it.
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Post by kcatthedog on Nov 1, 2016 9:06:28 GMT -6
If it was capsule; as it is single sided wouldn't it be working or not working ?
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Post by svart on Nov 1, 2016 12:11:42 GMT -6
Does it sound like a transformer or capsule issue to you? Those would be the 2 big ones that I don't wanna mess with. I'd rather not sink a bunch of money into it. Not at this point. It sounds more like you have an open in one of the differential signals to the XLR. You'd have a low, tinny, signal, high noise. I'd still go through and resolder all the joints. You'd be surprised how many times that's fixed stuff for me. |
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Post by EmRR on Nov 1, 2016 12:36:15 GMT -6
And then clean the crap out of the board to remove flux. I worked on one once and it became very thin sounding duecto board contamination. Cleaning brought it back. The reed switches are problematic too, why i worked on it in the first place.
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Post by markfouxman on Nov 2, 2016 20:31:45 GMT -6
First, make sure the jFET works correctly--measure voltages, which should be about half drop across R6, about 0.5-1.5V on Source and about the same on Gate. Then measure 0V after C8.
If all is good the problem most likely capsule, capsule's bias, or parasitic capacitance. Check for cold soldering and/or cracked traces under a magnifying glass. Make sure the reed switches are not stuck closed (I'd just get rid of those all together--they are not implemented well), thoroughly clean HiZ part with flux remover (or alcohol), as Emrr has suggested.
If still no luck most likely a capsule. Buy 50pF capacitor and solder instead of the capsule to emulate dummy source. If with normal gain on your pre (which works with other mics) it is OK and not noisy then here is your problem.
Best, M
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Post by indiehouse on Nov 4, 2016 18:38:51 GMT -6
Thanks! I'll give this a shot and see if I can get her working again.
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