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Comment: BOM 6N138 must be replaced with 6N139


15.Jan.2018LED-man1.1 BOM added, glitch issue, page design changes
20.April 2018LED-mangithub link added, firmware link, pcb version added
09.May 2018LED-manFirmware Versions updated, REV2.0 pcb page added
18.May 2018LED-manFirmware 1.2.4 with patches added
25.July 2018LED-manalfa3340 info, patcheditor links, firmware 1.2.5
29. Aug 2018LED-manpower wiring page created on subpage
25. Oct 2018LED-manupdate Firmware Versions, Stereo Output Mod
2020LED-mangeneral changes - structure of this page
10/2020LED-manbug on breakoutboard - C3 polarity is wrong
10/2021LED-manBOM outputboard - replace 6N138 to 6N139

Table of Contents

Table of Contents


DateLocationIdentified issue


Oct 20, 2017PCB: Motherboard rev 1.0

Steve Sommers - Capacitor C188 designation is duplicated. C186 is missing.

From Roman:

Oct 21, 2017

PCB: Voice card

Rev 1.0

 Resistors R40, R45, R151 and R146 have space on the circuit boards, but there is nothing specified in the BOM

These are not used and were left in place for possible filter modifications. Leave the components spaces empty (do not put anything there).

Nov 11, 2017

PSU Board

Rev 1.0

DACs not initializing on some boards. Note: Updated in BOM 1.0.8

PSU Board Changes per Roman: 

Change C12 to 1uf 6.3V or higher

Change C13 - 330uf 6.3V or higher 8MM DIA /3.5 LS

C13 increased delays the boot of +3.3v digital rail, c12 reduced makes 5v analog rail boot faster,
so, DACs start with no problem

Without change sometimes they don’t start, since digital 3.3v comes to DAC before 5v

Dec 23, 2017

All boards

Roman suggests that both power consumption, and heat reduction can be obtained by substituting all TL072/TL074 OPAmps with the lower current TL062/TL064. Roman also states that the pre-built units contained the TL062/TL064sThis was first suggested as a substitution for the voice cards only with TL072/TL074s being used on all other boards. However, Roman has since updated the BOM to use TL062/TL064s throughout. (REV1.0.9)

Jan 15,


All Voiceboardswaveform glitch not the same like CS-80

To apply the "glitch fix", you will need to solder two 1.0 Meg resistors per voice board, one for each oscillator. They can be easily added to the back side of the circuit board, so all existing components can remain unchanged.
In the schematic, the 1M resistors should be added to the voice board from IC4 pin 4 to +12V, and from IC4 pin 5 to +12V. Below is an image of the modification done to my voice board, showing you the optimal locations for the resistors to minimize lead length. The tolerance for the resistors is not critical at all, 5% resistors can be easily used. If needed, you can apply a small amount of silicon glue to hold the resistors in place, or even add insulation to the leads to prevent the possibility of a short. 

click to enlarge

2.October 2020 

DIY version

rev.1 only Breakoutboard PCB

Capacitor C3 - the polarity is wrong labeled on the PCB this affects the 5.2V power rail for the fan and USB.

remove the capacitor and install them with swapped polarity.

you can use a new capacitor 15uF 10V/16V RM2mm max.5mm diameter (as before)

ignore the schematics - there's a 100uF shown - but the BOM shows an 15uF capacitor

thanks to all involved people to report this bug.

10/2021all VersionsBOM failure

replace the 6N138 to 6N139 or you run in stucking notes 

(the 6N138 needs 4.5V but we only have 3.3V, the 6N139 runs fine with 3.3V) 

Bugtracker (not updated)

further bugs, issues, problems are reported here (here are user reported issues due to soldering failures or other issues reported too)