Delta 66 outputs

[sangram]

Hi

Don't know if this should be in Digital, but here goes.

My Delta 66 balanced outputs are acting funny. The hot signal is fine with 0 offset and a strong level, but the cold signal has no or very little signal and a very high offset - about 20 mV.

The card was picked up used, and for a long time was run using unbalanced inputs on other equipment, with the cold lead shorted to the shield. I continued till I got an amp with balanced inputs, and now it runs in balanced mode but it's still not fixed.

Would this kind of operation damage the opamps on the cold signal output? (5532 SOIC types) Or is this normal with the Deltas? Rod Elliot has described a 'balanced' scheme on his website which just lifts the cold signal from the signal ground, to create a pseudo balanced operation mode. Maybe this is what it is?

Didn't realise how bad it was till I got my new 1212M, which has a much hotter overall signal (quality aside) and a pure balanced output.