Symmetry issue with function gen EZ/Goldstar FG-8002

[rodcastler]

Hi,

My FG-8002 analog function gen (AKA GoldStar FG-8002) has a symmetry function that has the desired effect on symmetry however the knob also adjusts frequency, undesirably and quite substantially.

I would expect for the knob to adjust duty cycle, while keeping the previously set frequency steady.

I wonder if this is a design failure of this model or something broken that I should be able to fix.

[rodcastler]

I found the attached schematic for this unit.

I suspect that something fishy could be going on with U5 or U4, where the two (freq and symmetry) appear to mix.

Any thoughts on where should I begin? and most importantly, do anybody else experience the same issue with this unit? Like I said, I'm not sure if it is working per design...