As I grind my way through figuring what is wrong with this mic and how to repair it, I came upon an "O Cr@p!" moment when trying to disassemble it.
You see, the wiring that came up through the vertical bit to the head had fallen down and was flopping around loose, with the base.? Looking at? the inside of the head, I saw a phillips screw and throught, "Great!, I will remove the head from the stand and then I can feed the wiring up through the stand, then through the head."? and so on.
Dueing manufacture, the head is assembled to the base and held in place by that screw.? AND with glue!? The result is, if you're expecting the head to come off the base after removing the screw, it will but not in the way that you'd expect.? It broke.
Upon looking at the break, I could see evidence of glue that was the undoing of this mic.? Seeing that there was glue, I wondered if i could just do some "airplane glue" type joinery (IOW, was the glue similar to PVC pipe cement?).? It appears that I was correct and the head is back on the base but I'm going to be careful with it now.
If you lose the wiring through the base, the best way to get it back will be to fish some string down through the head and base and pull it back up that way.
It's a minor thing but may be useful to someone in the future.
I'm still troubleshooting the mic itself.? From what I'm seeing, the element in my mic is low-Z (hence the 400 ohm resistance across its terminals0..? Looking on my scope at 20 mV/div, I get a less than 20mV signal when I whistle into the element by itself (not connected to the mic).? I get signals of 50 - 100mV out at the white wire but before the connector.? Someone put a different element in there sometime before 2019, when I bought the TR7 that came with this mic.
The connection of the circuit is series cap --- primary || secondary -- series cap.? Transformer is 3 wires, so the cold sides of the windings are common-connected.
I'll be redoing all the connections and reassembling the 7077 with better workmanship.? I may not be able to avoid electrical tape but I'll at least know that the solder connections are good.
73,
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
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