Aquaboy DX @ 15V - D4 issue / Modulation LED

[dannoceti]

I built the Aquaboy DX (MN3005 with MN3101) and recently added add Road Rage PCB to give it a regulated 15v.  I made the suggested 15v changes from the build doc; R50 and R51 at 8k2, R13 and R14 at 36k. 

Once calibrated for 15v the pedal sounds really great, however D4 (rate indicator of the LFO) is way less acurate and seems to be almost always on, with just slight changes in brightness.  Note: at 9v's D4 was very accurate and would clearly flash on and off with the rate of the LFO.

Has anyone encountered this or know how to potentially fix.  I don't think I need to post all my voltages for this, but if necessary I will.

Thank you!

Dan

[madbean]

You don't need to post voltages. Try increasing the value of the two resistors used with the external indicator. These are R48/49. I think I suggested 8k2 at one point (the values need to be identical).

There may be some variation on how it behaves depending on what type of LED is used, I'm guessing.

[dannoceti]

Thank you, Brian. Looking at the schematic now that makes a lot of sense.

[dannoceti]

You don't need to post voltages. Try increasing the value of the two resistors used with the external indicator. These are R48/49. I think I suggested 8k2 at one point (the values need to be identical).

There may be some variation on how it behaves depending on what type of LED is used, I'm guessing.

Hello Brian,

quick question - if I increase R48 & R49 to something higher than 8k2 (like 10k or 15k), should I also increase R50 & R51 to the same values? or does it not really matter?

[madbean]

If you are happy with the modulation then no need to change. But, if it is too extreme then you can increase R50/R51 or put a large resistor in the optional R56 spot (I think 470k was suggested).