Re: GReg-Electrical Tech Journal Redux

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Greg wrote: Thu Dec 21, 2023 5:48 pm Anyone know of a place that does one-off sheet metal jobs using just a Fusion360 or "step" file?
I'm in the same boat. I actually have a Fusion 360 window open right now on my other monitor, where I'm drawing up a part for my antique car.

There are a bunch of small-run fab houses that will bid on stuff like this. I've used xometry in the past for some CNC aluminum work. I just let some machine shops duke it out for a couple days to win the job.

Some good recommendations here:

Re: GReg-Electrical Tech Journal Redux

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Lomo 19a19 work.

We have two mics with dissimilar tubes and coupling caps. Sourcing parts to make them same, and build a new power supply.

EAPreq500 project.

Some refinements on the partially SMD version of the pcb. Stuffed one prototype for testing. Having 60+ parts changed to SMD from through-hole saves a lot of time, and actually allows me to get more precise with the resistor values. Welcome to the year 2000, Greg!
Waiting on the chassis example to be fabricated.

Re: GReg-Electrical Tech Journal Redux

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Apogee Symphony Mk II -

Channel 1 output putting out DC, +11v on one pin and -11v on the other. This is the fifth channel that's done this.

Replaced the output driver opamp, which, I think I noted was a bastard to do last time because of a giant thermal pad on its belly. This time I did much better. My hot air jet isn't quite enough to get the chip up to temperature on it's own, but with the chisel blade soldering iron at about 700º baking one row of pins, while blasting the body with 750-900º from the jet, I was able to free it without obliterating the board.

Still no hint on what's doing this. Static? Someone patching phantom power to it? I should see if the last few times were in winter too, when the RH is about 20% in the control room, and pretty much every time I touch a chassis after moving there's a discharge.
Checked... last time was in mid summer... :u

Flying Faders channel 21 not moving.

Busted cable.

Moved temporarily to Channel 48 and disconnected from the computer until I have time to string it up with a fresh cable. I can still be used as a regular fader.

I'm hungry.

Re: GReg-Electrical Tech Journal Redux

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-Elsewhere-

Sphere Eclipse C

Channel 1 and 23 dump noise onto the Cue stereo buss

On the MM-301 modules, replaced IC1 (TL075) , the buffer amp feeding those particular sends, pre volume and pan pot.


Channel 16 can't send out the Cue stereo buss.

On the MM-301 module, reseated IC 1 (IC sockets are trash).


Channel 13 - Fader has no audio in "mix" mode.

On the MM-301 module, found a tiny metal fiber shorting the "boost return" signal trace to a neighboring ground trace.


Channel 3- Polarity reverse switch on the eq module cutting the signal intermittently in the natural, up position.

Replaced the switch (4P2T).


Signal to channel 15 on the tape machine from the patchbay losing one leg the balanced line.

Stressed pin on the EDAC connector, bent back into shape, reseated connector.


Discovered a possible mode to enable true fader flipping . There's a master button for this ("VCA to Mon") which doesn't do anything. Looking into it, it might be as simple as pulling a couple jumpers on the MM-301 boards (1-2, 7-8 and possibly one near the logic input at pin 47). Gonna try it next time I'm at the place. It'd be great to always have the faders feeding the 2-mix/monitor in every mode, and use the "monitor" pots to send to the busses.

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Neotek Elite-

Channel 19 small fader always sending signal, no matter where, in its travel. Signal is distorted sounding near and at the bottom of the range.

Measured 200+Ω between wiper and bottom terminal with the fader all the way down. Replaced the fader to get the console back up. Going to see if it can be cleaned later.

Installed and tested the first 2 stereo channels which were re-switched. Only discovered one problem with a missing jumper.

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