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Known Issues and Building tipps for yocto 808 Clone Batch2 - January 2014 pcb version


Failure in Cymbal Build Instruction before 11.02.2014

(copy von e-licktronic forum)

A customers found a mistake on the schematic.

R108* and R111* in the Cymbal section are switched.

The right value of R108* is 22K and R111* is 18K.

(the building instruction was updated to correct value on 10.2/11.2.2014)


R44 from 100k to 50k otherwise a 100k Trimmer to  change the„tuning range“ for TM1   (tick) validation July2014


unscrew the nuts from all pots/encoder or the board bends.

if needed use washers together with spacers

Custom Rearpanel:

i´m planning for a second yocto a rearpanel with powerswitch.

in the EPS file i removed the square hole for the powerconnection, i have to connect from the pcb the gnd cable to the switch, see here - same is in the LXR Drumsynth modification.

here is the modificated EPS file.



Custom LOGO:

added a "Rhythm Composer YOCTO at the Frontpanel

and removed the powersupply square cutting at the rearpanel (see custom rearpanel info above)


Noise section:

Measurement AC !!

Adjust the TM4 trimmer for  130mV on pin 1 of 4558.  

its important to use a good DMM (multimeter), most cheap DMM have in AC voltage measurement with 3digits high failure rates and cant display 160mV  - shows only 0,01.

i highly recommend a 4,5digits or better DMM with 0,1% tolerance


i have at least 250mV so changing R127 to 47K ...



for Handclap section:

hear the issue:

808 issue handclap:

This was a little tricky to figure out:

clap reverb mod -
replace r376 (47k) with 100k trimpot

This will vary the reverb between full and completely off.

C144 must have the correct polarity

you have to trim TM3 to get a handclap sound of your choice

make sure that your noise is trimmed between 100mV and 140mV AC (RMS)

please read the TR-808 Servicemanual, you find there addional infos about Gain  (you can change 2 resistors to minimize the gain of the handclap section)

if your Handclap reverb dont work:  measure with a scope the triggeroutput (Tranny Q29), you find it too on the R360 and the q69  ( you  must have this on both ! )


Range: replace  R44 to a 50k trimmer

adjiust the trimmer on left hand - after a bleedthru you must trim one trimmer a bit more to get a cowbell.

you can doublecheck them by using a scope

Low Noise Ratio (SNR) for Mastersection

change in the Mastersection all carbonfilm resistors to Metallfilm resistors and change all cheap electrolyt caps to LOW ESR caps..

change the ceramic cap (220p) to a c0g capaciator

Low Noise Ratio (SNR) for Mastersection

change in the Mastersection all carbonfilm resistors to Metallfilm resistors and change all cheap electrolyt caps to LOW ESR caps..

change the ceramic cap (220p) to a c0g capaciator

Noise Reducing SNR/NOISE RATIO generell

in many Voices/sections you can find at the output amps a resistor, to reduce the noise ratio you can change this resistor to a metallfilm resistor and the electrolyt caps to a better low ESR Cap.

Bassdrum: R175 1K, R173 6K8, R174 100K,C50 1uF/50V

Snares:  R207 1K ,   R210  470K,   C68 33uF/35V

Rimshot: R295 1K, R327 470K, R330 470K, C126 33uF/35V

Low Tom/Low Conga:  R235 470K, R238 1k, C82 33uF/35V

Mid Tom/Mid Conga: R266 470K, C95 33uF/35V, R239 1K

Hi Tom, Hi Conga: R291 470K, R294 1K, C109 33uF/35V

Hihat: R161 470K, R172 1K, C83 33/6,3V, R159 470K, R169 1K, C81 33uF/35V,

Master: all resistors, all Electrolyt caps ( 2x 2,2uF/50V, 3x1uF/50V, 33uF/353V)

Cowbell: R163 1K

Accent: all resistors to metall, C25 + C34 to Low ESR (2x 47uF/35V)

Cymbal: R166 1k, R128 470K, C78 33uF/35V

Handclap: R296 1K, R375 470K, C145 33uF/35V

Powersupply : all to metallfilm and all to low ESR caps ( 100R metall x 25  and 47uF/16V x25, 3x 100uF/35V)

powersupply main: C5,C7 2x 2200uF/35, C11 220uF/35, C12,C13- 100uF/35

=   4x 1uF35V (tick)

, 9x 33uF/35V,(tick)

2x 2,2uF/50V,(tick)

27x 47uF/35V, (tick)

3x 100uF/35V,(tick)

2x 2200uF/35V, (tick)

1x 220UF/35 (tick)

, 2x 100uF/35V (tick)

Shopping basket @

change the 100uf cap to 35V or more  in reichelt basket;AWKID=866139;PROVID=2084

metallfilm resistors don´t included there due to full homestock..