Neotek Elite-
Channel 13 wasn't sending to the busses or direct out with the large fader set as the source (fader REV button up).
One of the legs on the REV switch (6P2T) wasn't soldered. This wasn't discovered until recently because the channel spends almost all of its time in the reversed mode, with the large fader feeding the 2-mix and the small fader feeding the busses/direct out. All good now.
Channel 47 mic preamp phantom power not working.
Via in the C108 pad, carrying the 48 volts from bottom to top side of the pcb was torn out when the capacitor was removed. Replaced that cap again with one lying down so the top and bottom side could be jumper-ed with its leg easily. All good.
Installed tested and calibrated 2 re-switched stereo channels-
Stereo channel 5 has distortion on the input of the insert return (right side).
The polarity reverse switch is meant to have one leg lifted from the pcb. There was contact still.
This caused an irregular direct connection back to the insert return point from the input section.
Jon replaced the rest of the Edac panel connectors in control room A with DL ones. We're just about finished with that big project.
Re: GReg-Electrical Tech Journal Redux
102Rearranged some gear in studio A to accommodate a second Omnipressor.
Finished a pair of EA DI boxes for the studio with some old version boxes. We've had a few sessions which were extreme in their DI needs, and ran out.
Finished a bunch more EApreq500s and officially offering them up for sale now. Shipping November 1st!
Really glad to get these out there.
Finished a pair of EA DI boxes for the studio with some old version boxes. We've had a few sessions which were extreme in their DI needs, and ran out.
Finished a bunch more EApreq500s and officially offering them up for sale now. Shipping November 1st!
Really glad to get these out there.
Re: GReg-Electrical Tech Journal Redux
103Lomo 19a18 noisy
Tried cleaning, swapping capsules and cables to narrow down the noisy element. The head amplifier was causing the noise. I resoldered an iffy looking joint near the capsule connector. It looked like a resistor and/or capacitor leg was floating in solder on an eyelet terminal. This is in the sensitive, ultra high impedance part of the circuit. That might have been it, but I decided to redo a few more joints while I was in there. When the weather changes, these kind of things pop up more.
Tested for a long day, and all was silent.
Omnipressor
AKG D112- Dead
Capsule winding "opened up" This is an older version of the mic which AKG/Harman doesn't support anymore. It is now a turd-burger, as they say.
Looking for a replacement capsule from somewhere.
Finished 10 more EApreqs
Tried cleaning, swapping capsules and cables to narrow down the noisy element. The head amplifier was causing the noise. I resoldered an iffy looking joint near the capsule connector. It looked like a resistor and/or capacitor leg was floating in solder on an eyelet terminal. This is in the sensitive, ultra high impedance part of the circuit. That might have been it, but I decided to redo a few more joints while I was in there. When the weather changes, these kind of things pop up more.
Tested for a long day, and all was silent.
Omnipressor
AKG D112- Dead
Capsule winding "opened up" This is an older version of the mic which AKG/Harman doesn't support anymore. It is now a turd-burger, as they say.
Looking for a replacement capsule from somewhere.
Finished 10 more EApreqs
Re: GReg-Electrical Tech Journal Redux
104Studio B-
Phantom powered mics not working with mic input 21, no matter what preamp.
Checked the pin-1 ground connection at the mic panel downstairs and saw it was open. Both patch points for mic channel and console input were correctly grounded at the sleeve contact. I re-punched the shield of the mic snake, channel 21 at the patch bay punch block (that's a mouthful).
All is good again. Maybe it's time to freshen up all the sensitive punch block connections?
Phantom powered mics not working with mic input 21, no matter what preamp.
Checked the pin-1 ground connection at the mic panel downstairs and saw it was open. Both patch points for mic channel and console input were correctly grounded at the sleeve contact. I re-punched the shield of the mic snake, channel 21 at the patch bay punch block (that's a mouthful).
All is good again. Maybe it's time to freshen up all the sensitive punch block connections?
Re: GReg-Electrical Tech Journal Redux
105Sony C37p - Pushed back the rear side of the grill to keep it from rubbing the pattern select switch. The mic was working because of the plastic insulator (the switch is metal an in contact with the business end of the circuit).
MORE preamps!
MORE preamps!
Re: GReg-Electrical Tech Journal Redux
106Neotek Elite-
Quiet "bit bit bit bit bit bit bit bttttt bit" noise on the buses...
This happened once before, and the problem was a bunk large filter capacitor in one of the power supplies.
I probed around and found the noise on the ±18 volt rails of the second supply. I replaced it with the spare we bought because of the last time this happened. Time to rebuild this one... 27 years of being ON roughly 24/7/365. Not bad!
Quiet "bit bit bit bit bit bit bit bttttt bit" noise on the buses...
This happened once before, and the problem was a bunk large filter capacitor in one of the power supplies.
I probed around and found the noise on the ±18 volt rails of the second supply. I replaced it with the spare we bought because of the last time this happened. Time to rebuild this one... 27 years of being ON roughly 24/7/365. Not bad!
Re: GReg-Electrical Tech Journal Redux
107Royer 121-
Quiet and murky
Before taking a peek at the ribbon, I did a horizontal rotation listening test. If the ribbon is stretched, you can usually hear it move or flop as it gets rotated upside down. I could hear it move a bit, took a peek and saw it was stretched out. Off to Royer...
-Elsewhere-
IRPA MK12
Modified a power supply and built a cable for this mic, tested it for 5 days straight in the studio.
Quiet and murky
Before taking a peek at the ribbon, I did a horizontal rotation listening test. If the ribbon is stretched, you can usually hear it move or flop as it gets rotated upside down. I could hear it move a bit, took a peek and saw it was stretched out. Off to Royer...
-Elsewhere-
IRPA MK12
Modified a power supply and built a cable for this mic, tested it for 5 days straight in the studio.