Difficulty

Moderate

Steps

4

Time Required

                          45 minutes

Sections

1

  • Analogue Isolator Potentiometers
  • 4 steps

Flags

2

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  • BackKorg Volca Sample (MK1)

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Introduction

The replacement part that you need is a 5-pin ALPS potentiometer which is impossible to find and purchase, or sold at very high prices (for a simple pot).

With this guide I will show a DIY solution to repair your filter pots on the device.

What you need

Step 1

              Getting infos about the part
  • The VS service manual is impossible to find, but it is well known that the two filter pots are 10K ALPS potentiometers
  • By online search, you can find the KORG EM-1 service manual, which uses the same kind of pot for volume control
  • The pot is VR2, an ALPS RK09K12C 5-pin potentiometer
  • By searching on old ALPS datasheets, you can find the specs for the pot and the layout
  • Looking at both the layout and the EM-1 schematic, we can see a shared ground (pin 1) and the remaining connections which form a dual wiper

The VS service manual is impossible to find, but it is well known that the two filter pots are 10K ALPS potentiometers

By online search, you can find the KORG EM-1 service manual, which uses the same kind of pot for volume control

The pot is VR2, an ALPS RK09K12C 5-pin potentiometer

By searching on old ALPS datasheets, you can find the specs for the pot and the layout

Looking at both the layout and the EM-1 schematic, we can see a shared ground (pin 1) and the remaining connections which form a dual wiper

1024

Step 2

              Getting the right replacement part
  • You will need a simple 10K stereo potentiometer with 6 pins
  • The ALPS is a 103B, which is a linear one. I used a LOG one which works anyway (it will have a different sweep compared to a linear)
  • You will have to bridge the two 1-1’ pins together to have a shared ground
  • The next step is to solder 5 cables to the pins (only one is needed in the shared ground)

You will need a simple 10K stereo potentiometer with 6 pins

The ALPS is a 103B, which is a linear one. I used a LOG one which works anyway (it will have a different sweep compared to a linear)

You will have to bridge the two 1-1’ pins together to have a shared ground

The next step is to solder 5 cables to the pins (only one is needed in the shared ground)

Step 3

              Wiring
  • You’ll have to follow the layout drawn in the image
  • Solder the 5 wires and reassemble the VS, then check if the pot is working

You’ll have to follow the layout drawn in the image

Solder the 5 wires and reassemble the VS, then check if the pot is working

Step 4

              Success!
  • Now you have a perfectly working filter section on your volca, enjoy!

Now you have a perfectly working filter section on your volca, enjoy!

To reassemble the device, follow these instructions in reverse order.

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Attached Documents

  • ALPS Pots
  • PDF - 901.05 kb
  • View
  • Korg Em 1 Service Manual
  • PDF - 1.29 mb
  • View

ALPS Pots

PDF - 901.05 kb

Korg Em 1 Service Manual

PDF - 1.29 mb

Author

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                    Bob M

Member since: 10/23/2020

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