The old humming console

We are starting to work at a new client’s studios.  It is a bit like stepping into a 1980s time machine, as the newest console seems to be the Broadcast Audio console in the FM studio.  I feel I should wear a wide colorful tie and part my hair in the middle when working there.  There is also an older UMC console in the second production room.

A what?

Exactly.

It seems the UMC console (UMC was a Connecticut-based console manufacturer that was later sold to Broadcast Audio) was having an intermittent hum problem on all the audio buses.

After poking around under the hood for a few minutes, I decided I should begin with the basics.  Checking the power supply for ripple seemed like as good a place to start as any.  This console has a 30-volt and a 12-volt power supply.  The 30-volt supply checked out good, but the 12-volt supply, not so much:

12 volts DC, 2.7 volts AC
12 volts DC, 2.7 volts AC
12 Volt power supply
12 Volt power supply

2.7 volts AC on the 12-volt DC power supply.  That will put some hum on the audio, all right.  I tried to replace the power supply main filter capacitor, but it had no effect.  The regulator must also be bad and it is a Motorola part number which is likely not made anymore.

12 volt linear power supply
12 volt linear power supply

This is a pretty standard off the shelf power supply, I should be able to get one from Mouser for about $60.00 or so for a linear unit, which will be cheaper than us trying to trouble shoot and repair the old one.  In the meantime, I took the 10 amp 0-30 volt bench supply and pressed it into temporary service.  The console is working again, for now.

At some point, all this old, um, stuff needs to be replaced.

3 thoughts on “The old humming console”

  1. Okay on the ties, I don’t remember much of the 80’s fashion as I was overseas for most of it.

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