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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