McMeat - Color pot issue

[Joep]

Hi McMeat builders,

I finally finished boxing up my own version (!!) And I ran into (like other builders) the Color pot problem. The Color pot doesn't seem to work properly, the range is very  limited.

In the past I already checked everything aaround the circuit. And still I'm 99,99% sure the schem matches the drawing and PCB. This evening I again checked everything and compared the schem to the Mutron for reference. Again I did found nothing wrong.......BUT have a look at the values of the McMeat components I found something strange. R16 is used to provide bias the the opamp circuit of the filter, and actually this value (1K5) is relatively low, espacially with you take in mind that connecting something to Vref is the same as connecting something to ground if you look at a circuit from an AC point of few.

I guess R16 need to be something around 1Meg (1,5Meg will make sense here)

Any opinions about this?

Moosapotamus, If you still have an original, are you able to check this values of R16, it's between the Color and Intensity pot on the PCB.

I'll try this tomorrow (it's already 1:00 at night here...)

Bye,

Joep

[markusw]

Hi Joep,

did a LTSpice simulation and if the simulation is OK with 1.5M the colour pot does not respond. With 1.5k and lug 2 and 3 conected LTSPice predicts the response to be smooth.

Markus