Agilent 81150A distorted sine and ramp waveforms

[Jeff_Birt]

Hi all,

I'm looking at an Agilent 81150A Pulse Function Arbitrary Generator. It fails the POST with; Channel 1: Selftest of Data Out failed. There is no service documentation or even an explanation of what each self-test does test.

In operation it seems to work fine for square waves, but sine and ramp waveforms are distorted at amplitudes above 100mv. Distortion increases with amplitude. This sort of failure seems familiar, but I can't remember where I have seen it before.