preenfm Forum

PreenFM => preenfm2 and preenfm3 => Topic started by: Synthusiast on January 11, 2023, 01:10:33 AM

Title: [solved] Preen FM2 loud noise, barely hear synth
Post by: Synthusiast on January 11, 2023, 01:10:33 AM

Hello I have the Preenfm2 RD5 board.
My output is only giving nothing until I am in the top 90% of the volume pot and then it's only producing white noise and very faint synth notes when using the instrument + button on left method to hear it.

I scope traced the noise back to the opamp but not sure if its before. Hard to trace this board. I was wondering if I could get some troubleshooting help or the schematic for it?
Also, is there a layer of trace in between? One of the pads burnt out on one side of a switch but it's functioning. Wondering if theres a connection in the middle of the board, not just front and back.

Thanks!

Title: Re: Preen FM2 loud noise, barely hear synth
Post by: Xavier on January 14, 2023, 08:06:23 AM

Hi,

Here are some troubleshouting ideas you can follow.
https://ixox.fr/forum/index.php?topic=63509.0
Maybe starting by checking the voltage points in message #6.

Preenfm board are 2 layers board. Bottom and top, you can follow every track.

R5d schematics are here :
https://github.com/Ixox/preenfm2/tree/master/hardware/PCB_R5d
It requires an old version of Kicad but i think the PCB file can be open in latest one.

Title: Re: Preen FM2 loud noise, barely hear synth
Post by: Synthusiast on January 18, 2023, 04:28:04 PM

Thanks for the help! It ended up being resistors being in the wrong spots.