Sunday, August 2, 2009

Midas Verona

Because it's the FOH console at Lincoln Berean and inconvenient to take out of service, this was an in situ repair. Aux busses 7 and 8 were reportedly intermittent and hence banned from use (see the "X"s in the second pic).

With the help of Corey Simmons, the head system tech, the trusty $1 Discman-turned-signal-generator was patched into the first 32 channels or so to track down the origin. Amazingly Aux 8 was actually observed to work fine and be low in level with a high-pass. It had the characteristic sound and EQ of a barely-made connection in a ribbon cable somewhere. The right side never exhibited an issue through the testing while the whole left bank of channels would come in and out. Thus, the first place to check was the connections from the master section to the left.

Now, usually such a ribbon cable search involves tipping the whole mixer up 90 degrees, pulling the bottom panel, and a good measure of educated guessing. Midas, however, made this console so the top steel panels could be removed from above without needing to remove anything other than a few screws and fader caps. All the rotary pots come through holes a bit larger than the knobs and therefore do not need removing.

Apparently the original installer needed to open it up for a headphone amp issue and was told (after destroying a few) there's a special tool to unseat the ribbon connectors. This is the only Midas in town I'm aware of, so obtaining the tool wouldn't yet be in White Audio's best interest. With the gauntlet thrown, I went to work on the aux bus ribbon connectors with a few flat-blade jewelers' screwdrivers and small pliers and removed them. My guess is the tool has tabs which open the locking tabs on either side and grip to allow parallel extraction, similar in idea to the tool for extracting after-marked car stereos.

The connector positions are spade-type with a pinching female side. Perfect candidates for a bit of oxidation and lessening pinching force to create intermittent and high-resistance connections. Symptoms I've seen with this setup are of the "It works for a few minutes/hours and then it just goes away" type due to changing temperatures from being powered on.

Testing after putting it back together gave the all-clear. The real test will be for the next Saturday/Sunday services since intermittents only fail at critical times..

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