babyhead

G7 trouble shooting
« on: April 10, 2008, 12:36:18 AM »
Hello-

I have a sick G7. I took it out of my studio to record some drums (which sounded GREAT)  and when it came back there was no audio coming out. I would normally be the one to say 'put some signal in and trace it' but this is a special case. I have voltages...

~160v after the 10k
~80v after 100k, anode and before 2.2uf
~80v after the voltage division
~9v, ~18v and 0v  at the capsule in cardiod. (looks right given the input Z)

The anode voltage looks screwy. I get pops when I touch any of the amp parts with my meter, but none when I touch the capsule contacts.

I dont want to rebuild the mic... so any suggestions...

80v seems low for the anode.

Thanks-


steppenwolf

G7 trouble shooting
« Reply #1 on: April 10, 2008, 05:39:20 AM »
80V after the plate resistor should be fine, same on mine...
Stupid question:
Did you swap the tube, are the heaters all right?
Did you check the power supply for loose connections, or even more obvious,
did you check your cables?
I had that with my 7wire cable from power supply to mic. I kept one connection a little short in the 7pin XLR connector and it ripped off...
Good luck with it!

babyhead

G7 trouble shooting
« Reply #2 on: April 10, 2008, 11:51:04 PM »
PSU is good.
Swapped to my trashy EF86- no luck.
Cable's good.

The capsule (dale m7) looks fine...

I think it's time for a new G7... cannibal style.
I have electrical fiberglass, turrets and a holesaw on order...

  :twisted:


 

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