Dreadmaster motorboating

[JebemMajke]

I've made dreadmaster using this schematic

Voltages are insane
Ic1
1 8,4
2 8,39
3 6.15
4 0
5 6.7
6 6.7
7 8.9
8 8.95

Ic2

1 8.4
2 8.3
3 6.7
4 0
5 6.7
6 8.28
7 6.7
8 8.9

Help plz

[slacker]

How are you generating VREF? I can't see it on the schematic. Have you measured what voltage it is, the problem could be there.

[JebemMajke]

Beats me but that schem is pretty close ( if not the same ) as the original, which also lacked the usual 2 caps, 1 resistor generated vref. Those are connected to each other. My guess is that my plate is not etched properly. So tomorrow I'll do another one.

[posmaster]

I have to agree - it looks like the design is wonky - from the website the PCB shows a 47K from ground to ground next to the electro.

The first thing I would suggest is replacing the electro with the 47k to get your divider set at the very least - I don't see an easy junctions where the electro could be moved to though at a glance.

[JebemMajke]

I've made another one using this plate and layout


Can someone explain that 10uf and 47k resistor next to gain pot?

I'm starting to hate this thing ... It's messing with my brain.

[slacker]

The 47k and 10uf are supposed to be the bottom of the voltage divider that make VREF. The 47k is connected incorrectly though, both ends of it are connected to the same trace, which is ground. The end nearest the 10uf cap should connect to the trace going to the + side of the cap.
If you follow the trace that connects to the + side of the 10uf down to the bottom of the board there's another 47k that connects from there to 9 volts, making the top of the divider.
If you follow that trace up just past the top TL072 there's a square pad that doesn't seem to connect anywhere so that might be another mistake, meaning VREF isn't going  everywhere it should, I haven't checked.

[JebemMajke]

I've noticed that 47k is not doing anything. It's connected to ground on both ends

[JebemMajke]

I've got it to work. Ps gain pot needs rewiring. But this thing sounds like a ton of crap. Really bad. I guess i ll have to mod my riot a bit more to get it to fit in this box.