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GReg/Electrical Tech Journal

All your geeky questions about electronics, microphones, tape machines, etc.

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Re: GReg/Electrical Tech Journal

Postby greg on Fri Oct 04, 2019 11:39 am

Audio Kitchen Little Chopper Amp -

Blows mains fuses whenever turned on.


Pulled all the tubes, which essentially unloaded the power transformer, and it still blew the fuse. Checked the mains voltage switch, then found shorted filament windings.
Steve at Audio Kitchen sent us a nice shiny new power transformer, wired it in, and we're back to loud again.


Some patchbay ground hum hunting, fixing. A couple of poor punches on the block.
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Re: GReg/Electrical Tech Journal

Postby greg on Mon Oct 07, 2019 4:31 pm

Skibtronics LA-2 clone-

Distortion on clean bass.

No distortion around me and my testing.

Pricing new run of Electrical DI Boxes (Jensen ap note with XLR In/Out). Someone is interested in buying a set of 4.
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Re: GReg/Electrical Tech Journal

Postby greg on Mon Oct 07, 2019 4:39 pm

greg wrote:Gefell 563 -

No output.

Busted wire on 5-pin XLR end of the cable.

Seems trivial to mention these things, but maybe it's good to note the frequency.


Not the same parts as a above...

Gefell 563 -

Crackling, intermittent output.

Problems could be stimulated by wiggling the microphone end cable/connector.
Replaced really old, and stressed 5-pin female cable connector. Mic was fine...
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Re: GReg/Electrical Tech Journal

Postby greg on Tue Oct 08, 2019 5:16 pm

Looks like the new Avid HD I/O has cross coupled balanced outputs! We have two which came with some other things we picked up. I wonder if there was enough people like me whining about the old 192s to change things?
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Re: GReg/Electrical Tech Journal

Postby greg on Fri Oct 11, 2019 4:58 pm

Neumann SM-2 SM-23 work...

Orange Amp filament supply...
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Re: GReg/Electrical Tech Journal

Postby greg on Wed Oct 23, 2019 5:58 pm

AKG 414 B-uls

Another busted frame. Someone pretended it wasn't broken and sheepishly returned it to the mic drawer.

This will be the 3rd or 4th?

Trying some JB Weld on this before ordering a new frame.
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Re: GReg/Electrical Tech Journal

Postby greg on Thu Nov 07, 2019 9:30 pm

Related...
Sony C500 webbing frame on the inside of the windscreen was broken in some joints. JB Welding that as well.
I had to remove the capsule to keep it safe. The screws on the clamp were lacquered in place. It took some work to get them out. I would just scrape the threads with a needle tip, back the screw as much as possible, then scrape some more...
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Re: GReg/Electrical Tech Journal

Postby greg on Tue Nov 12, 2019 1:09 pm

-Elsewhere-
Sphere Eclipse C -

Auditioning a modification on a channel in efforts to replace the VCA faders with a regular old audio one.

Found and repaired some bad wiring in and outside the console.

ATR 102 1/2" 2-track (stock) -

Urethane Capstan Surface turned into melted ice cream then solidified again over everything beneath.

This was a mess.
Removed all the parts and panels in the area, and cleaned, and cleaned, and also cleaned. The photo transistor lens for the capstan tach was glued to the encoder glass on the motor. It popped off when I was trying to remove the photo transistor pcb. Glued it back on once everything was clean. Installed the new capstan assembly, with fresh urethane surface. Performed the mechanical and electrical capstan tach alignment. Took apart the takeup tension roller and cleaned everything. The parts were glued together. This would have been a great time to replace the bearings, but we had none, and they moved apparently well.
Machine is back together and singing.
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Re: GReg/Electrical Tech Journal

Postby greg on Fri Nov 15, 2019 6:05 pm

AKG C12 (Siemens 204/23) No38-

Replaced noisy tube.

Sony C500 tested after reassembly (epoxied broken parts).
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