2-ACA Output Trafo Conundrum

I'm currently testing my console and am trying to make sense of what I found regarding the trafo output of the 2-ACA summing and buffering board. With no load I get a nice representation of the 8k square wave (looks pretty much exactly as the "signal generator" [Moog Modular] puts it out). This is measuring pin 2 to ground.

But with the converter input connected the signal changes to a higher amplitude but more triangle/sawtooth like pattern.  The converter shouldn't put a lot of load on the signal, and the discrete op amp / output trafo combination should handle a modern converter input easily.

Any idea what's going on here and what to do about it? Thanks!

This is what the output looks like with the converter connected.

What about sin wave? I'd be inclined to see what happens when loaded with 600...assuming a/d is 10k input.

Looks kinda like the  High Frequency Loss/phase shift here on this chart????

shabtek said:

What about sin wave? I'd be inclined to see what happens when loaded with 600...assuming a/d is 10k input.

Click to expand...

Sine wave looks all right, but it also increases in amplitude.

Do you think adding 600 accross the secondaries might cure it?

Not clear what you mean with pin2 to ground--are both ends of secondary connected or is one floating?

shabtek said:

Not clear what you mean with pin2 to ground--are both ends of secondary connected or is one floating?

Click to expand...

Oscillator tip touches pin 2, Oscillator ground touches ground. Pin 3 measures similar to pin 2 (it's the other side of the transformer secondary after all).