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Korg Synth MS-10 Pitch Bend Repair
By Gary | March 2, 2008
Below is a video in which I discuss a pitch bend problem in a Korg Synth MS-10. The main thing is how to look at the schematic and determine what voltages should be present in the circuit.
Where the fun begins is when you don't have the voltage present and you have to figure out why.
Korg MS-10 Power Supply Schematic
Click on the link above and you can view a portion of the schematic...As you can see the + and - 15 volts D.C. are the output of the analog power supply. I isolated the pitch bend assembly so you can see how the voltage is presented to both sides of the pot.
As you turn the pot it gives the desired output voltage that the synth player is looking for to drive other modules on the synth. The customer's problem is that is wasn't working at all. The problem ended up being an oxidation buildup on the molex connector that connects the pot pitch bend assembly to the main board where the power supply components reside.
So it was a simple repair but in the video you can see how I came to this determination and also by studying the schematic.
 learn MiDi korg m3 m1 triton ms 20 2000 le studio DVD US $24.99 |
 Korg MS 20 MS20 MS 20 Owner Service Manual s US $4.99 |
Topics: keyboard repair | 5 Comments »
May 26th, 2008 at 7:53 pm
Hi Gary
I’m digging the video…my MS-10 is now famous!
Take care
Peace
spudzzzz in Ethridge
June 22nd, 2010 at 1:17 pm
Hi Gary – I’m just curious about how you remedied the oxidation buildup in the molex connector? I fear my own MS-10 may have the same problem. I have applied some de-oxit to the male end of the connection (mounted on the motherboard) but I’m not sure how to get the inside of the molex connector clean.
Thanks!
June 22nd, 2010 at 1:27 pm
Hi,
Sometimes it’s easier just to find which one of the traces in the connector is not connecting. (Checking with an ohm meter for continuity) And just hard wire a jumper wire in place between the circuit boards or preferably just jump around the molex connector. That way it’s hard wired and you don’t have to worry about the equipment marching back in for the same problem.
Of course if you can replace the connector that works or bend the pins out enough to have tension between the teeth and the mounting post and it makes a tight connection.
That Funk Out by Peavey that I talk about is good for this also.
Gary
August 17th, 2010 at 10:52 pm
gary….don’y know if you’ll get this…..i am living in mexico and am experiencing problems finding a repair shop here to fix my lazy key with my yamaha p-80 electronic piano….you were a tech guy?……wondering before i open my piano up…..if you had any idea on the degree of difficulty……the key is the c above middle c….does’nt react well…..falls midway….i can get parts shipped here……thanks……jim
August 17th, 2010 at 10:55 pm
Hi,
I believe that one can be a bit of a bear, I’ll dig around and see what I can come up with. Usually when it returns half way, the key is broken in the back where it pivots, kinda the weak point. You might have the tension spring loose for the return but usually that doesn’t happen.
Gary