01/W Power: Battery and AC

Power Topics

Noise from the Power Supply

AC Power
rev: 2015Aug15p1142


The Battery Everyone Has

There is a battery inside the 01 that is used to retain information while power is turned off. The 01/Wpro and proX use a common type CR2032. (Other 01 models likely use the same battery but I don’t have confirmation on that.)

This is one of those round, thin (“coin”) lithium 3-volt batteries (190–225 mAh). One technician said batteries are shipped measuring 3.2 volts and are considered dead at 2.8v. For maximum battery life, keep spare batteries cool or cold. (Some people keep batteries in their refrigerator, but probably not the freezer). Don’t keep them in a warm place (104° F / 40° C or warmer).

Radio Shack has CR2032s (US$5–$9) but they may be cheaper elsewhere. (Try one of the discount stores with “dollar” in their name. Real scroungers may find LED candles that use an easily-removable CR2032. I got three for $1.)

The Other Battery

There is a different battery on the PROG/SEQ DATA card that plugs in the back of the 01. It powers just that card, not anything inside the 01.

Battery Life

How long your battery lasts seems to depend on which model of 01 you have. Batteries in 01s with a disk drive seem to last longer than those in 01s that don't have a floppy. Why?

01s with a disk drive (fd models) save edits made to Global settings, Progs, and Combis. (You are expected to save sequences to disk yourself). 01s without a disk save all those edits plus sequences. This may shorten battery life in non-fd models. An fd battery can have a life exceeding 9 years.

Technical Theory

Essential data is stored in two SRAMs (IC30, 31 wired as 32Kx16). When the 01 is turned off, a circuit automatically switches the SRAMs over to get power from a battery. There is a charging circuit that recharges the battery while the 01 is turned on. (The 01 must be turned on, not just plugged in the wall). While power is off, the battery supplies power via the “VOUT” line. The battery charging circuit (IC33) includes a comparator (IC32) that sends a signal (INT BAT) to the CPU to display “Battery Low (Internal)” if the battery voltage drops too low.

“Battery Low (Internal)” message

A “Battery Low (Internal)” message is supposed to appear when the battery should soon be replaced. There has been a report that a battery died without displaying any messages, and all custom Progs & Combis were lost (since they hadn't been saved to disk). Lesson: Back-up your work to floppy or to a computer using a SysEx MIDI Dump.

When “Battery Low (Internal)” appears, the manual says “Contact your dealer, or a nearby Korg service center”. However, reports are that it is easy to change the battery yourself except for all the screws you have to remove and re-install.

Changing The Battery

An excellent video showing how to change the battery in an 01/W pro is at http://www.youtube.com/watch?v=0Dt6iiuQWY8.

(Note: I haven’t yet replaced my battery so the following is compiled from reports from others. E-mail me if anything should/could be updated.)

  1. Save any custom work to disk (or an external MIDI device) before opening your 01 - you may have to re-load everything after you replace the battery. Factory Progs and Combis are stored in ROM so need not be saved.

  2. Open your 01. How you get at the battery depends on which model you have. You may want to consult the disassembly instructions as a guide on how to get inside.

  3. Replace the battery. The battery is mounted on the main circuit board. One user (Ed Edwards) wrote:

  4. Re-assemble your 01.
  5. If personal edits are missing, re-load what you saved in step 1. Factory sounds can be reloaded by following these steps.

01er experiences are described in text on the web. Search for something like “korg 01/w battery”. Random examples are Gearslutz and Korg Forums. But if you can play videos, the patpatpat999 YouTube video is the best I’ve seen.

A00: Init Combi

If you see the Combi “A00: Init Combi”, you need to load the factory Progs and Combis from ROM. This process is called Initializing or Resetting the 01.

Whines, hums, and other noises

Whines, hums, and other noises have been traced to these sources:

AC Power



This information comes from documentation for the 01/Wpro and proX. I suspect this information is identical for all 01/W models, but this has not been confirmed. Be very careful when working around power supply circuits. Using wrong parts or making other mistakes can result in damaged equipment or even a fire. BE CAREFUL!

AC Power Overview

The 01 takes AC power directly from the wall. It does NOT use a “wall wart” (a box/cube that plugs in the wall and has a dangling wire). Different countries have different mechanical plugs and sockets and internal connections.

On my US model, the 01 power cord has a female connector on the 01 end. It is the same as power cord commonly used with desktop personal computers.

Internally, from the 01 socket the power goes through filtering circuits (inductors, capacitors) and a fuse on the way to a transformer. The transformer has various taps that are connected depending on the country the 01 was being made for.

There are two output circuits from the transformer, one for generating plus and minus (+/-) 12 volts, and one for generating +5 volts. These use standard voltage-regulator circuits and ICs. Each transformer circuit has a series fuse followed by a full-wave (bridge) rectifier. The rectifier output has filter capacitors on the way to 3-terminal regulators. The 12-volt circuit uses a 78M12 and 79M12. The 5-volt circuit uses a PQ05RF2. The 5-volt regulator also feeds a voltage inverter circuit to power the EL backlight for the LCD display.

Changing Voltages for Foreign Countries

Visitors to this section typically want to learn whether they can change their 01 to work with the power available in another country. Theoretically, you can. But I've never done it, and I don't know anyone who has. All I can do is give you the information I have and wish you luck.

To convert the power in your 01, you need to address three areas:

  1. Changing a connection on the power transformer primary winding.
  2. The four fuses, which to change.
  3. How to physically plug your 01 into a different wall socket.

For help getting inside your 01, check the disassembly instructions page.

Transformer Connections

The schematics show a power transformer (Part #TC-046, Part Code 400012700) with six input taps:

The schematics show connections to Common and 100V. This may be the connection for Japan (even though the schematics are in English). I suspect the US connection is to 117V. (If anyone can verify this for the US or any other country, e-mail me and I’ll enter the information here.)

Korg seems to have identified the following voltages with the following countries:

Code Country? Code Country? Code Country?
100JP Japan? 220GE ? 230SE ?
117EX ? 230GE ? 240AF ?
117CN Canada? 230FR France? 240AU Australia?
117US USA? 230WG West Germany? 240GE ?
230SC ? 240UK United Kingdom?

The circuit shows the transformer has two secondaries, one center-tapped, the other not. The secondaries are connected to the circuit board with a cable that has a 5-pin connector called CN21A. The pins are:

Checking voltages

If you decide to try and change the primary tap and fuses (for travel to another country), it would be wise to unplug CN21A before turning it on the first time. Measure the AC voltages on the pins of CN21A to make sure they are correct before plugging it into the rest of the circuit.

Unfortunately, the schematics do not show what these voltages should be. (If anyone measures them, e-mail me and I'll enter them on this page.) Here's a circuit description:

The center-tapped secondary feeds a full-wave bridge rectifier through connector CN21A. One output of the bridge is connected to a 7812, the other to a 7912. The center-tap is ground to the regulators.

The other secondary feeds a full-wave bridge rectifier. One bridge output connects to a +5-volt regulator (PQO5RF2). The outer output connects to system ground.

I've forgotten what you want the peak or RMS voltage to be at the secondary (break out the old textbooks) - probably about 2 volts (peak) higher than the regulator outputs (to cover the dropout voltage)

Power Consumption

These are printed specification, not necessarily actual:


The schematics show four fuses in the power supply (see table).

01/Wpro & proX Fuse Ratings
Label Location 100-120V 220-240V
FU1 Transformer Primary 250V  800 ma 250V  T250 ma
FU2 + 12 V regulator 125V  1.6A 250V  T800 ma
FU3 - 12 V regulator 125V  1.6A 250V  T800 ma
FU4 + 5 V regulator 125V  6.3A 250V  T3.15A

When you buy a fuse, you specify a current and a voltage. The voltage spec for a fuse is not necessarily the exact same voltage as what you find at the wall plug – it’s a way of rating a fuse.

Note if you change the transformer primary voltage you must change the fuse in the primary circuit.

How does a fuse work?

A fuse is a specially designed length of wire that melts when the power gets too high. Power is a combination of voltage and current (specifically, voltage times current) – the more power, the more heat. A circuit malfunction can cause too much current to flow. This increases the current (power) through the fuse, and it (hopefully) melts before a more expensive component does. It is very important to replace fuses with the same value the circuit was designed for.

Power Cord for a Foreign Country

Wall sockets in different countries have different physical configurations. If it were me, I'd buy two power cords that mate with the 01 socket  in my native country (one cord as a spare, just in case) and take them with me. Once I got to the new country, I’d go to the local electrical store and buy two wall plugs. I’d cut the original plugs off the cords I brought in my home country and attach the new plugs.