Page History

As you can see you also need to do a jumper wire between the solder point marked A on the pixie cpu and pin 10 (!WE pin) of *any* of IC 7,8,9 or 10 (they’re all connected to the same signal)
Please note:
* This is on the back of the 808
* you solder the pins on the cpu on the “wrong“ side
* the jumper wire can be soldered directly as it’s just one wire, I use a pin header and patch cable here mainly during development as I can easily remove the cpu without having to desolder anything
* as the cpu is upside down, make sure you connect the midi wires the correct way!
* as always - pin 1 and 42 is unused and can be left unconnected (pin 1 is the hole with a square pad)

Do not fit the DC jack on the PSU circuit board. Its not used and it is not wired correctly.

use a cable for the jack as shown for example

heres a tip about the installation of the tactile caps:

  credits to a FB User..

for the voice board: 

first install all 1/8watt resistors on bottom of the pcb R1-9 are 1/8w or the switchboard do not fit

use MLCC caps there and no IC socket. for IC1.

when you have a solder frame: install the flat Trannys and ic sockets before you install the other parts

credits by Martin.J.K  - Thank you

install a jumper as shown to get your 808 working as designed

install a 10nF polyester cap or bipolar electrolyte cap at the sync jack or on the pcb

Hi tom noise level = R273
Middle tom noise level = R245
Low Tom noise level = R216

BassDrum Endless/Extended Decay -- replaced R170 (470k) with 370k resistor in series with a 100k potentiometer. then i set the potentiometer to the 'sweet spot', where the extra decay sounded best to me, and measured the resistance of the 370k resistor plus the resistance of the potentiometer setting. on my Yocto, 445k was the nicest value for self-oscillating/extreme decay . then i removed the 370k resistor and potentiometer from R170, and finally replaced R170 with an SPDT switch that selects between a 470k resistor (the original value/normal setting) and 445k (the 'sweet spot' for extra decay i measured, using a few resistors to achieve the 445k value).

BassDrum Tuning -- replaced R165 (47k) with SPDT switch that selects between original value (47k) and a 100k potentiometer (audio/log preferably)

BassDrum Tuning Envelope -- replaced R166 (6.8k) with SPDT switch that selects between original value (6.8k) and a 5k potentiometer in series with a 2k resistor. (in combination with the tuning mod, this mod enables some nice extra-punchy bass drums!)

Clap Noise Offset -- replaced the 10k trimpot in the clap section with 10k potentiometer..

Closed Hihat filter -- replaced R147* (2.7k) with an SPDT switch that selects between original value (2.7k) and a 10k potentiometer in series with a 1k resistor

Open Hihat filter -- replaced R153* (2.7k) with an SPDT switch that selects between original value (2.7k) and a 10k potentiometer in series with a 1k resistor

 some help.. found on FB

the 3D printed part is available in my shop https://www.diysynth.de/spezial-re-808-parts/re-808-midi-anschluss-3d-druck.html

or print it myself (Resin preferred) 

just use 2 screws to mount this at the typenumber plate holes at the rear and drill a small for the MIDI cables.

this tool make things easier.

just drop the rotary switch inside and its easy to saw the switch to the exact given length

available in my shop :

https://www.diysynth.de/spezial-re-808-parts/re808-schaltersaegehilfe-3druck-teil.html

for much easier rotary switch assembling, use this knowledge PLUS the ALPS assembly guide, my infos are a additional tip how to remove and bend the tabs.

Background:

we dont need the upper part of the D shaft switches

and we don't need the lower part of the knurled switches.

for the D shaft switches you can bend the tabs at the bottom for removal as close you can - because we dont need the upper part - put the upper part (metal) in the trash bin.

for the knurled switches you can cut the pcb on bottom to remove the bottom part without bending the tabs, after you have removed the pcb - you can much easier bend the tabs !!!

remove R333 and install a 50K trimmer from solder side - this adds the opportunity of changing the Clap frequency/bandpass

Install a header for the Noise Tranny of the PCB Solderside - you can try different Noise transistors of your choice (less white noise at the snare, gain stage between handclap and Snare, a loud Handclap is wrong, too much white noise at the snare is wrong)

forget the 133mV AC measurement of the noise Tranny - the important thing is the spectrum of the noise.

use a transistor tester (peak tech for example to get the correct polarity or use the datatsheets)

Furthermore: (highly recommend)

you change c51 from 0.47uF to 0.68uF (or up to 1uF) to get more reverb/room on the Snare.

use milled pins on the solderside for testing the value.

Only do this mod when you are lucky with the snare sound except the reverb part is too small (personal choice)

its not recommend to do this mod until you have found a good noise transistor otherwise you have too many variables.

in case your cowbell is out of the trimmer range while calibration 800hz/540hz install in parallel to R44 a 10K resistor and the same for R55 (add a 10K in parallel)

since we connect a scope there, let enough space to clip the probe there.

Image Added   Image Added

in case you have failures in the cowbell, here's a good page:

visit http://frisnit.com/roland-tr-808-cowbell-rebuild/

make sure you have a groundcable from the 2 Jackboard pcbs to your DC-DC PSU- otherwise the sequencer do not start 

I recommend a cable from the sync jack ground to the Dc-DC psu GND pads too, the 808 case is powder coated and you can't get a true earth there without scratching/removing the paint.

some users get a buzz/clickinmg sound by touching the case or metal parts.. that's the reason - you need a solid ground from the case and jackboard pcbs to the PSU.

mount the DIN jack from inside of the Case - don´t install the DIN socket thru the metal case, in case of trouble shooting its much easier with the wiring - otherwise you have to disconnect/desolder some cables.

Here are few pictures, how I installed LED resistors on sockets, to change easily the brightness of the LEDs.