FG 504 function generator odd behaviour


Colin Herbert
 

I have an FG 504 which is showing some odd behaviour. The triangle-wave shows asymmetry in that the negative peaks of the wave are rounded-off at any frequency and the positive ones have a similar but lesser problem at higher frequencies. This also seems to manifest itself as what looks like cut-off on the negative peaks of the sine-wave and lesser cut-off on positive peaks. While the triangle-waves are more-or-less symmetrical, the sine-waves are definitely not so, showing a nearly three-to-one voltage ratio in favour of positive peaks. There is also noticeably overshoot on the square-waves at anything above 1kHz and only a DC offset at frequencies below 80Hz.
I am totally ignorant of how this function generator produces triangle-waves, but I do understand that the square-waves and sine-waves are derived from the triangle-wave. Does anyone have any help that they can offer? I would be grateful to get this useful function-generator working properly.
Colin.

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