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Old January 10th, 2010, 04:58 PM   #1
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sony ecm77b broken?

a sad story:

i bought an ecm77b lavalier a couple of months ago from ebay, i wanted to use it for a shoot i had coming up but in the end it wasnt delivered on time, stupidly since then i didnt even get around to checking the thing worked.

this evening plugging it into a zoom H4N, with a new battery and clipping the lav to around the correct area of the chest i need to speak in a loud voice with mic input level at full to get a -24db signal, this is giving obviously a really bad Signal:Noise ratio..

I've tried with and without phantom but it doesnt help..

Am i (hopefully) forgetting something or is it a write off???

Very dissapointed :(
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Old January 10th, 2010, 08:03 PM   #2
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Manus,
Here is one thing you can try. The top part of the mic capsule (the part with the openings where the sound gets into the mic) has the ability to be unscrewed. Check to see that it is not loose. If it doesn't appear to be loose take it off completely and then put it back on.
This will reseat the connection at that point. Might not be the problem but its worth a shot.
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Old January 10th, 2010, 08:44 PM   #3
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I've used 77's and it's very easy for the wires going into the battery case/XLR plug to get twisted and broken. Open it up and check. They're easy to resolder, but do require a steady hand.
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Last edited by Paul Cascio; January 11th, 2010 at 10:40 AM.
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Old January 10th, 2010, 09:13 PM   #4
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One silly question plus silly comment, so please ignore at will and take the advice of those who are more competent and wiser than me.


1. When you tested with the battery inserted, did you select phantom power "off" in the H4n? There may be some sort of switching arrangement for battery power when AC phantom power is present on the line.

2. I don't know what the phantom power requirement of the ECM-77B is or whether it is flexible. If it is 48v, then the H4n will be underpowered at 24v. I had a similar experience when attempting to power a Sony C74 mic from a Cinema Products mixer which supplied power for a Sennheiser 815.
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Old January 11th, 2010, 04:42 AM   #5
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thanks..

so i opened it up, it doesnt look too pretty inside, where the 3 wires are coming from the capsule theres some frayed threads exposed..

ive tried with the phantom on with and without the battery inside the mic, apparently the sony takes 48v so i selected this in the zoom (theres the option of 24 or 48v)..

The recorded sound is actually not bad just that it has a high level of hiss, if i speak directly into the mic i can get a level closer to 0db but i guess theres a problem with the wiring meaning the signal being sent out is much too low..

im hopeless with soldering and electronics so i guess a trip to a local audio/repair shop would be the next step..
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Old January 11th, 2010, 10:17 AM   #6
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Appears you've found the problem. If one of those wires are marginal or totally disconnected you would get about half the signal. What happens with some of those Sony mics is the cable gets twisted at the xlr end because people don't unscrew the battery cover correctly. They twist the cable part around instead of the sleeve. That would explain the broken/frayed wire. Good news is that mic is more repairable than most. The specs on the 77 state that it can take phantom voltage from 12 to 48 volts, so that shouldn't be an issue at either setting. Once you get the mic repaired if 12 volts works as well as 48 you can save some battery life in your recorder. Or better yet just run it off its internal battery. The AA will go for a very long time.
Best,
Bernie
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