Master:
The master section is where all the sounds are summed. The original TR-808 OPA is a μPD4558 but it can be replaced by another with a better signal / noise ratio. Prepare all components before beginning assembly. List of components:
Image | Description | Part | Value | Qty |
Ceramic capacitor (221) | C18*, C22* | 220p | 2 | |
Polyester capacitor (2A102J) | C20* | 1n | 1 | |
Electrolytic capacitor | C21* | 33/25 | 1 | |
Electrolytic capacitor | C7*, C8* | 2.2/50 | 2 | |
Electrolytic capacitor | C17*, C19*, C23* | 1/50 | 3 | |
Diode | D9*, D10* | 1N4148 | 2 | |
PNP Silicon Transistor | Q10*, Q12* | 2SA733 | 2 | |
NPN Silicon Transistor | Q11* | 2SC945 | 1 | |
Silicon N-Channel JFET Transistor | Q13* | 2SK30 | 1 | |
1/4w Carbon resistor | R66*, R68*, R73* | 10K | 3 | |
1/4w Carbon resistor | R67* | 1K | 1 | |
1/4w Carbon resistor | R69* | 100K | 1 | |
1/4w Carbon resistor | R70* | 100R | 1 | |
1/4w Carbon resistor | R71*, R72* | 220K | 2 | |
1/4w Carbon resistor | R74* | 330K | 1 | |
1/4w Carbon resistor | R75*, R76* | 33K | 2 | |
1/4w Carbon resistor | R77* | 22K | 1 | |
Dual Operational Amplifier | U4 | µPC4558C | 1 | |
Potentiometer (A503) | VR1* | 50KA | 1 |
Make it:
![]() | Here is Master |
![]() | Solder all resistors. Solder each value one after the other. |
![]() | Solder both diodes 1N4148 MAKE SURE DIODES ARE IN THE RIGHT WAY |
![]() | Solder polyesters capacitors |
![]() | Solder electrolytics capacitors MAKE SURE ELECTROLYTICS CAPACITORS ARE IN THE RIGHT WAY
|
![]() | Bend the central lead of 2SK30. Install the transistors. Do not get confused between 2SC945, 2SA733 and 2SK30 are not the same transistors.
MAKE SURE ELECTROLYTICS CAPACITORS ARE IN THE RIGHT WAY |
![]() |
Connect the power transformer. Test 4558 power supply. The green dot is-15V, the red dot is +15 V (plus or minus 5%). You have the ground on the potentiometer big square pad . Still check that the four wires from the power supply is well connected.
THEN DONT FORGET TO DISCONNECT THE POWER TRANSFORMER. DO NOT SOLDER COMPONENT AS THE CIRCUIT IS POWERED ! |
![]() | Solder the 4558. To insert it into the PCB you have to bend the leads a little. |
![]() | Finally return the PCB and solder potentiometers on the opposite side of components. VYou can then go to Sequencer assembly |
Follow us