KLM-509A replacement board

About cKLM-509A replacement

Battery leak of an original NiCd battery in Korg Poly-61 synthesizer on control board KLM-509A/475 (shortly 509A/475) causes corrosion of vias, parts’ mounting holes, electric traces and electronic components (caps, ICs, transistors etc.). Metal parts are covered with white oxides and blue-green salts. Corroded metal can’t conduct anymore, so part of control board fails and it is not possible to program and play sounds.

Here is a list of some important 509A board’s tasks:

  • Provides Control Voltages for synthesizer blocks as DCO waveshaper, VCF, VCA
  • Is responsible for keyboard scanning
  • Generates pulse waveforms with its DCOs
  • Includes Tape Interface

It is a very hard job to repair a PCB affected by battery corrosion. It is necessary to restore all affected traces, mounting holes, vias and to find not working parts (especially ICs).

Another solution is to use a cloned 509A, that’s why the name cKLM-509A. It is almost an identical copy of original 509A board. The parts are located on the same place and the board uses the same types of parts. The schematic of the circuit is as original one. The cloned board can be easily repaired and calibrated in the future using original Poly-61 service manual.

Use original MCU from the old board. If your MCU is faulty or is missing, a replacement MCU is available.

Hard-to-find IC37 (reset IC MB3761) was replaced with a modern equivalent.

 

Korg Poly-61 uses three different control board versions:

KLM-475 with small auxiliary board KLM-515 (early Poly-61 version)
This was the first control board version.

KLM-509A (improved Poly-61 version)
Later KLM-515 and KLM-475 were fitted together. In this way a new 509A control board was created. It is a full-blown replacement for old 475+515 boards.

KLM-509A with 8049-587 (IC1) and 8049-588 (IC30) MCUs (late Poly-61 version with factory MIDI)
This 509A board is identical to previous 509A board; it only uses upgraded 8049 MCUs (codes 587 and 588).
8049-587 and 8049-588 MCUs are especially designed for Poly-61 with factory MIDI implementation. But these MCUs also work fine in Poly-61 without factory MIDI.

CONCLUSION: The cKLM-509A can replace any version of control board!

 

2x different VOICE BOARD VERSIONs:

KLM-476 voice board with auxiliary board KLM-478 (early version)

KLM-508(A) (later version)
Later KLM-476 and KLM-478 were fitted together. In this way a new 508 voice board was created. It is a full-blown replacement for old 476+478 boards.

CONCLUSION: The cKLM-509A will work both with 476 and 508 voice boards!

 

FFC (flat flexible cable) connectors vs. PLUG connectors

  • Due to two different voice board revisions there are two types of CN34A connectors (located on control board). Old voice board 476 uses plug connector, new voice board 508 uses FFC.
  • If your 18 pole FFC is faulty ask us for a replacement cable

 

FOR SALE

  • 1x new cKLM-509A clone board with original straight and angled connectors
  • cKLM-509A is a drop in replacement for the old, original KLM-509A/475 board
  • Choose your variation: either for voice board KLM 476 or KLM 508 (the ONLY difference is the CN34A connector)
  • The board comes tested and with factory presets to the customer! No need to adjust/check the cKLM-509A board!

 

cKLM-509A:  CN original for VB 476

KLM-509_original_01

KLM-509_original_02

KLM-509_original_03

KLM-509_VB-476

cKLM-509A:  CN original for VB 476

 

cKLM-509A:  CN original for VB 508

KLM-509_VB-508_04

cKLM-509A:  CN for VB 508

 

 

Recommendations and hints when replacing 509A

Be sure female connectors on 475/509A (or even other boards) aren’t corroded. Individual connector’s contacts are visible from the side. All of them should have nice, silver metallic colour. If they are blue-green, white or dark grey they should be cleaned or replaced.

Be sure battery leak on 509A didn’t damage neighbouring boards.


 

Replacement male connectors for KLM-509A board (and other boards) + replacement contacts

  • For sale are original 6 and 8 pin straight connectors for KLM-509A / 475B board or other boards in Poly-61 (and other Korg synths, e.g. Monopoly)
  • These parts are NEW
  • Making 14 pin connector: 14 pin = 1x 6 pin and 1x 8 pin
  • Making 18 pin connector: 18 pin = 3x 6 pin
  • Making 12 pin connector: 12 pin = 2x 6 pin

 

  • Replacement contacts can be used to replace old, corroded contacts. Connector housing can be reused after cleaning. In combination with replacement male connectors, almost all connector junctions can be repaired!

jst_male-8-pin

jst_male-6-pin

jst_male-side

Replacement 6 and 8 pole connectors

jst_contacts_2

jst_contacts_1

Replacement contacts


 

About Poly-61 MCU replacement

Battery leak of an original NiCd battery in Korg Poly-61 synthesizer on control board KLM-509A/475 (shortly 509A/475) causes corrosion of vias, parts’ mounting holes, electric traces and electronic components (caps, ICs, transistors and so on). Metal parts are covered with white oxides and blue-green salts. Corroded metal can’t conduct anymore, so part of control board fails and it is not possible to program and play sounds.

Sometimes aggressive battery leak affects IC1 and IC30 on control board and they stop to work. These ICs are microcontrollers (or shortly MCU) that are heart of control board.

There are two MCUs on 475/509 control board. One is responsible for Key Assigner (suffixes 217, 384 and 587) the other one for Programmer section (suffixes 337 and 588).

 

337

384

 

Key Assigner MCUs

  • 8049-217 – first version (also used in Korg Polysix on KLM-366(A/B) board)
  • 8049-384 – second, improved version, will work instead of 8049-217
  • 8049-587 – usually installed in Poly-61M with factory MIDI

 

Programmer MCUs

  • 8049-337 – installed in all Poly-61 synthesizers without factory MIDI
  • 8049-588 – usually installed in Poly-61M with factory MIDI

 

FOR SALE

  • 1x 8749-384 or 337 replacement
  • These MCUs are a drop in replacements for old/original MCUs
  • Manufacturer NEC or Intel

 

all

The picture shows where to install 384/337 MCUs

 


Pricelist (in EUR) & ORDERING

Please, place order via E-mail! Normally we response within 12 hours.

 

 

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