Korg BX-3 (Gen 1) Support
 This is Korg’s dual-manual version of the original Korg CX-3. It is literally two CX-3 organs in one case with the added feature of vibrato and chorus.
It is distinguishable from the second-generation BX-3 because its drawbars are to the left of each manual.
This keyboard is known by several aliases, analog BX-3, BX-3 v1, and BX-3.1.
Because the two manuals are independent of each other, there are a few things you can do with a BX-3 you cannot do on a Hammond B3.
For example, you can select percussion on the lower manual, and you can tune the manuals independent of each other.
Contents
Visit our Facebook group for announcements, discussions, and more information about supporting the Korg BX-3.
We put a lot of time into creating, gathering, and organizing the information in this page.
If you found any of this to be useful to you, especially if it helped you to make or save money,
please
to help us continue making content like this available.
We are also raising money to help us purchase the equipment we need to be able to offer parts and
service for this and other products. Please visit our
Electronic Hardware Purchases page for details and
consider making a contribution.
For most repair situations, our service is a mail-in repair of one or more circuit boards inside the equipment. This is to get around the prohibitively expensive round-trip shipping that would otherwise be required. Typically, we work with your local technician. Sometimes, all your technician needs is a little direction from us. In other cases, they can remove the circuit board(s), send them to us, and replace them once they are returned from us. If you are versed in the basics of electronic repair, you can act as your own technician if you’re comfortable with that idea. At most, you may need a decent low-wattage soldering iron and a basic multimeter. If you would like for us to service the whole organ, you will need to arrange it with one of our service technicians using the Support request form.
The following services are for individual circuit boards inside the BX-3, and include return shipping. If you’re not certain what’s wrong, use the Support request form and we will help you. The most common approach is to purchase a circuit board repair service for each of the circuit boards you’d like for us to repair. These services will get your circuit boards into our shop and then back to you when they are diagnosed or repaired. This includes the initial checkout, diagnostic, and report, as well as final testing of any repairs.
Once you make your service purchases, you will receive an email from Parastream with a
list of items for you to ship to us, and our shipping address.
When your shipping box arrives, you will receive an email with an estimated starting date for your job. Repair services are performed in the order in which your shipping box arrives.
After we receive your main board and perform the initial evaluation, you’ll receive an estimate for what we believe it will take to repair the circuit boards. We work hard to catch every problem in the estimate, and we are successful in the vast majority of cases. Due to the complex nature of the circuitry in the organ, there may be other problems hiding behind what we found in the initial estimate.
The estimate is good for 30 calendar days. If you do not respond within 30 days, we will make multiple attempts to contact you through all means you disclose to us (email, phone, etc.). If we still cannot reach you after an additional 15 calendar days, we will return your circuit boards to you.
If you choose to proceed, go to our website and order the services specified in the estimate. When we receive the order and payment, we will place your repair order in the queue for repair. Once the repairs have been performed and have passed all tests, they will be carefully packed and shipped back to you. Although exceedingly rare, the post-repair testing may find additional problems that need to be addressed. This situation can go one of two ways.
- Hopefully, we can identify what we believe will fix the circuit boards and give you a new estimate. If you decide to proceed with another round, order the indicated services. If you decide not to invest further in the organ, we understand. We can either return your circuit boards as they are, or refund the shipping portion of your initial repair purchase to you and we retain the boards.
- Although this has never happened so far, we could find a problem so severe that it becomes impossible for us to do a proper repair. In this case, we can either return your circuit boards as they are, or refund the shipping portion of your initial repair purchase and we retain the boards. We would prefer to keep our perfect repair record if it is at all possible!
If you are purchasing parts or other items along with repair services, they will be shipped in the same box with the circuit boards when the repair services are complete. This is done to minimize shipping charges.
If you would like the parts to be shipped to you separately, place them on a separate order.
Services
Given the history of leaking electrolytic capacitors with this organ, and the organ’s age (in the 40s), we recommend replacing all the electrolytic capacitors with new ones unless they have been replaced within the past 20 years. You have two easy options from Parastream. You may purchase a capacitor kit for the whole organ and have your technician (or yourself) install it. Click here for more information and ordering. Your second option is to have us do the recap for you. Purchase the circuit board repair services for each circuit board in the organ and include the capacitor replacement add-ons.
The tone generator circuit board is the large one behind the keyboard, and is the only one that can be removed without soldering wires. To remove it, pull off the connectors, remove the screws holding it down to the baseplate, and you should be able to pull it free.
Begin by purchasing the Korg KLM-244 Circuit Board Repair. This gets your circuit board into our shop and then back to you when it is repaired. This includes the initial checkout and report, as well as final testing of any repairs. If you want both circuit boards (upper and lower manuals), order two.
You may add additional parts or services listed below, or you may order them later as instructed by our repair technician. There is no service item for replacing an SM304A, SM305A, or SM305B; just add the parts to the order. If it is not currently in a socket, add Korg KLM-244 Circuit Board 40-pin Socket Installation (07-01002200). It is the same for the 50241 Top Octave Generator. If it is not currently in a socket, add Korg KLM-244 Circuit Board 16-pin Socket Installation (07-01002300). Parts specified as (Pulled) have been removed from socketed circuit boards and have been functionally tested in a Korg BX-3.
| Description | Part Number | Availability | Unit Price (USD) | Quantity | Ordering |
Korg KLM-244 Circuit Board Capacitor Replacement Service | 07-01002100 | Available | $33.65 | | |
| Korg KLM-244 Circuit Board 40-pin Socket Installation
Service | 07-01002200 | Available | $12.67 | | |
| Korg KLM-244 Circuit Board 16-pin Socket Installation Service | 07-01002300 | Available | $8.60 | | |
| ¼ Hour Additional Tier 2 Labor | 07-99000100 | Available | $16.25 | | |
| IC, Siemens SM304A Keyboard Encoder, PDIP-40 (New Old Stock) | 39-00003041 | In stock | $90.00 | | |
| IC, Siemens SM304A Keyboard Encoder, PDIP-40 (Pulled) | 39-00103041 | 5 in stock | $65.00 | | |
| IC, Siemens SM305A3 Organ Tone Generator, PDIP-40 (New Old Stock) | 39-00003051 | In stock | $90.00 | | |
| IC, Siemens SM305A3 Organ Tone Generator, PDIP-40 (Pulled) | 39-00103051 | 2 in stock | $65.00 | | |
| IC, Siemens SM305B Organ Tone Generator, PDIP-40 (New Old Stock) | 39-00003052 | In stock | $90.00 | | |
| IC, 50241 Top Octave Generator 30% Duty Cycle, PDIP-16 (New Old Stock) | 39-02050241 | 1 in stock, more in 30 days | $60.00 | | |
| Electrolytic Capacitor Kit, Korg KLM-244 Circuit Board | 92-90000200 | 10 day lead time | $18.00 | | |
The control / mixer circuit board is mounted on the underside of the drawbar assembly and contains the tact switches and control potentiometers. To remove it, unmount the entire assembly containing the drawbars (this varies by organ model). There are 5 or 6 wires directly soldered to pads on the circuit board which must be desoldered. Carefully document where these wires go when you replace the circuit board later. Unplug the connectors and remove the mounting screws.
Begin by purchasing the Korg KLM-245 Circuit Board Repair. This gets your circuit board into our shop and then back to you when it is repaired. This includes the initial checkout and report, as well as final testing of any repairs. If you want both circuit boards (upper and lower manuals), order two.
You may add additional parts or services listed below, or you may order them later as instructed by our repair technician.
The power supply / rotary effect circuit board is mounted on the bottom plate of the organ on the left side near the back. To remove it, unmount the entire assembly containing the drawbars (this varies by organ model). There are several wires directly soldered to eyelets on the component side circuit board which must be desoldered. Carefully document where these wires go when you replace the circuit board later. Unplug the connectors and remove the mounting screws.
Begin by purchasing the Korg KLM-246 Circuit Board Repair. This gets your circuit board into our shop and then back to you when it is repaired. This includes the initial checkout and report, as well as final testing of any repairs.
You may add additional parts or services listed below, or you may order them later as instructed by our repair technician.
The chorus/vibrato circuit board is mounted on the center of back plate of the organ. To remove it, pull off the connectors, remove the screws holding it down to the baseplate, and you should be able to pull it free.
Begin by purchasing the Korg KLM-308 Circuit Board Repair. This gets your circuit board into our shop and then back to you when it is repaired. This includes the initial checkout and report, as well as final testing of any repairs.
You may add additional parts or services listed below, or you may order them later as instructed by our repair technician.
At this time, there are no upgrades available for the BX-3 (we’re working on some!).
We have nearly every part needed to repair a BX-3. The most common component failures on a BX-3 are, in decreasing order of occurrence, are:
With the exception of mechanical parts, a failure in other components almost never occurs. We do not recommend replacing parts other than those listed for “good measure,” especially transistors.
The BX-3 circuits contain several transistors in matched pairs that should be replaced only if necessary.
We highly recommend replacing all aluminum electrolytic capacitors, given the age of these organs and the problems we have seen over the years.
We keep inventory low to keep part freshness as high as possible.
| Description | Part Number | Availability | Unit Price (USD) | Quantity | Ordering |
| IC, Siemens SM304A Keyboard Encoder, PDIP-40 (New Old Stock) | 39-00003041 | In stock | $90.00 | | |
| IC, Siemens SM304A Keyboard Encoder, PDIP-40 (Pulled) | 39-00103041 | In stock | $65.00 | | |
| IC, Siemens SM305A3 Organ Tone Generator, PDIP-40 (New Old Stock) | 39-00003051 | In stock | $90.00 | | |
| IC, Siemens SM305A3 Organ Tone Generator, PDIP-40 (Pulled) | 39-00103051 | 2 in stock | $65.00 | | |
| IC, Siemens SM305B Organ Tone Generator, PDIP-40 (New Old Stock) | 39-00003052 | In stock | $90.00 | | |
| Description | Part Number | Availability | Unit Price (USD) | Quantity | Ordering |
| Aluminum Electrolytic Capacitor, 10µF, ±20%, 16V, Subminiature Axial | 32-10032520 | 10 day lead time | $0.25 | | |
| IC, Panasonic MN3004 512-Stage Low Noise BBD, PDIP-14 (New Old Stock) | 39-01003004 | 30 day lead time | $46.00 | | |
| IC, Panasonic MN3009 256-Stage Low Noise BBD, PDIP-8 (New Old Stock) | 39-01003009 | 30 day lead time | $25.00 | | |
| IC, Panasonic MN3101 Clock Generator for MN3000 Series BBD, PDIP-8 (New Old Stock) | 39-01003101 | 1 in stock | $15.00 | | |
| IC, 50241 Top Octave Generator 30% Duty Cycle, PDIP-16 (New Old Stock) | 39-02050241 | 1 in stock, more in 30 days | $60.00 | | |
| Tact Switch, 12mm x 12mm x 4.3mm Flat | 50-01000001 | In stock | $1.75 | | |
Important information for Customers outside the US:
If you choose to ship via International Economy,
Parastream can only guarantee that your shipment arrives at the point of entry into your country.
The tracking number may not provide status once it reaches your country.
Parastream will not be able to offer any assistance in tracking your shipment once it reaches your country.
If you require complete end-to-end tracking and delivery guarantees, you should choose Standard International.
More information...
We recently had a customer post a detailed step-by-step procedure for replacing
keys in a Korg BX-3: https://www.flickr.com/photos/cavemusic/5442306025/in/set-72157626041701006.
We put a lot of time into creating, gathering, and organizing the information in this page.
If you found any of this to be useful to you, especially if it helped you to make or save money,
please
to help us continue making content like this available.
We are also raising money to help us purchase the equipment we need to be able to offer parts and
service for this and other products. Please visit our
Electronic Hardware Purchases page for details and
consider making a contribution.
Visit our Korg BX-3/CX-3 Gen 1 Troubleshooting page if you would like to take a crack at repairing your BX-3.
Manuals
IC Datasheets
Theory of Operation
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