Korg M1 buttons repair and full recapping

This the repair and recapping video of my Korg M1 synthesizer.
I repaired the dodgy buttons, by replacing the all tact switches
I swapped all the electrolytic capacitors.
I've tried to be as informative as possible in showing how to take the synth apart, and which screw to unscrew. (It was about 70 in total)
I also show which capacitor goes where, their values and if they're polarized or bi-polar capacitors.
There's also a description of which replacement tact switch I used, and which I think Korg used.
There's a full BOM (Bill of materials) at the end of the film.
Your M1 might differ since there might have been more revisions and mine is an early one with a serial just over 30.000.
Music starts at 6:22 and is all made with just the Korg M1.

[@ferenclucas2842]

excellent video. and you did a fantastic job on the theme music with one m1. I have taken mine apart a couple of times. to resolve my tack switch issues I opted for just the deoxit instead of replacement this time. it worked very well they are good as new for now. I would love to recap mine but that seems daunting. I have had mine since 1988 new from the music store, as a kid it was all my savings at the time plus some help from a parent. would never sell it :)

[@tukler2]

Thank You! Yes, synths can have a sentimental value. In my case it's the Korg Monopoly I've had since I was a kid and I'll never part from it. I'd recommend practicing soldering a lot first on other cheaper stuff and building things like guitar pedals or cheap electronic kits and also desolder components from old scrap circuit boards before doing synths.

[@careydixon8189]

Thanks Anders...I've replaced my battery but declined then to do the tactile control work(time). And Im 1st a prog drummer so.lots of others gear & guitars to deal with. Had issues getting memory via sysx Midi to save & as all controls are beyond use so I hoped to use sysx to get around it to see why/if the memory would hold. It simply doesn't store it likely due to some small setting issue as the battery is correctly placed & all else functions fine. Thanks for this tutorial advice. (I use a MOTIF XF at this time but never should've moved my workstation out of Korg as I love the work flow & other concepts. Bought mine in 1990.

[@tukler2]

The sysex process is not very intuitive. Try to find some M1 sysex tutorials. To check the memory, you could record something simple to the sequencer. If it's still there after a reboot the memory works.

[@OhRaez]

I bought a used Korg M1, which has no issues so far. Everything sounds great, and no issues with buttons or memory. But watching this ahead of time, just in case, and this is AMAZING. Gives me confidence when/if the time comes to change anything. Thank you very much for this

[@drdan4331]

Thank you for taking the time to put this video together :-)

[@tukler2]

Thanks! :-)

Fantastic video! Thank you very very much for posting this. I have acquired an M1 and I am in the process of getting it back in shape. This video is the greatest help. Enjoyed the music as well!!

[@tukler2]

Thank You very much!

[@morganlundin5029]

Now this is how you make a "how to fix things" video. Impressive !

[@magicknight8412]

I need to do the buttons on my newly acquired M1, buttons arrived today so looks like my evening is taken up now !

[@tukler2]

Hope you're a good friend with your screwdriver, thats the hard part. Have a pleasant evening and enjoy the soldering!

[@magicknight8412]

@@tukler2 I am tempted to buy a cordless/electric screwdriver :) thanks

[@magicknight8412]

@@tukler2 okay thats over an hour of taking it apart. Loads of fluff and dust along with a metal paper clip in there!

[@stevegeorge6131]

Very well done. I just got one in with power failure. NO screen. First thing: inspect power supply PCB and replace any factory lytic caps. Then : lytic caps on the main PCB

[@tukler2]

Check that all the voltages from the power board are ok and within spec first. Look for loose or unplugged connectors and reseat them all. Try to go fore the simple things first.

[@arthurcrime]

Very helpful video sir, I I have an m1 ex with some bad buttons, and I am about to set out to repair it. Thank you very much.

[@tukler2]

Thank you and good luck with the repair!

[@arnoldsretrokeys189]

Looks very nice, I am working on my Korg M1 PSU and do a full recapping of all 21 condensers on the board. Geep up the good work.

[@tukler2]

Thanks! Good Luck and happy soldering!

[@commonpike]

Excellent ! Plus, nice music.

[@rgardelion]

You are the best i saw in youtube grazie 1000

[@wojciechuy2137]

Thanks for the video, learned a lot!

[@newmusic4059]

Awesome video, thanks Anders

[@tukler2]

Thank You!!!

[@jerrysband7852]

Obvio estoy viendo este video desde la Tierra Caliente, Estados (México, Michoacán, Guerrero, Oaxaca... Etc.) dónde sobresalen estos teclados sintetizadores por el tipo de música que se toca ahí. Saludos de parte de su amigo Jerry y la Frecuencia de México.

[@SynthsStories]

Thanks a lot for your video 👍

[@davidmorarobles5884]

Great video! Thanks a lot fot sharing the knowledge!! Hi from Costa Rica!!

[@tukler2]

Thank You David!

[@markmdn6307]

Well done!

[@mcweb1036]

Thanks for this top Video 👍

[@samnapraw4289]

Posiadam 3 sztuki korga M1. Dwa sprawne jeden ma zepsute potencjometry joistic. Korg M1 to najlepszy instrument. Mialem ensoniqi inne korgi yamachy ale korg M1 to korg M1. Dlatego mam trzy sztuki

[@tukler2]

Maybe soon you'll have a 4th one too ;-)

[@samnapraw4289]

@@tukler2 myślałem o czwartym. ;););)

[@sergiorodrig]

thanks so much dude !

[@CHRADIO100]

Very nice

[@joseantoniocortesrometo7015]

Excelente msntenimiento

[@poznajelsek]

beautiful labour of love, thanks for sharing, I am keeping it for reference because after 34 years my trusty M1 started to hiss alternatively from both channels (headphones and main output) when volume is up, it's not influenced by OSC levels or other parameters: could it be the D/A board?

[@tukler2]

Yes it could be in the D/A board or some filter after the D/A, but before the outputs. Could be a bad capacitor somewhere. Check to see if it also on output 3/4. An oscilloscope could be useful to trace the noise. Good luck! /Anders

[@user-hq6qx8yc9c]

👍👍👍👍

[@themanbehindthebird121]

Korg god thank you 💙

[@tukler2]

Thank You!

[@joemcg3247]

Great Job, Great Video. Changed my M1 battery twice - still showing low, and display are is very dimmed out. Any tips? Thanks, J

[@tukler2]

Is it's a fresh battery and orientated the right way with the positive side up? I don't think I can help you. But I'd start troubleshooting with a battery that measure fine and is fresh. Does the synth drain the battery or is it OK with the synt reporting the battery low message. does the synth keep the memory when powered off? The display could be dim because of old age but otherwise that could be an indication of a fault. I'd check all the connectors, the voltages and the grounding points are grounded. Look for things that look broken or burnt and check for leaky or bulging caps.

[@corri303]

Thank you for this great video. Do you still have notes of the capacitor dimensions? I'd like to order new caps, but without physical dimensions it's not possible. Thank you.

[@tukler2]

Here's my list with the Mouser number. There are a couple of capacitors that I had to bend slightly to fit. I think it was the 470 uF. I used 35 volts ones with a hight of 20mm. I'd probably go for a 15 mm or 16 mm instead. 667-ECA-2CHG010 Aluminium Electrolytic Capacitors - Leaded 1.0UF 160V ELECT NHG RADIAL 667-EEU-EB1H100S Aluminium Electrolytic Capacitors - Leaded 10uF 50V 667-ECA-2GHG470 Aluminium Electrolytic Capacitors - Radial Leaded Al Lytic Cap Radial NHG Series 105C 667-EEU-EB1H101S Aluminium Electrolytic Capacitors - Leaded 100uF 50V 667-EEU-FC1H221S Aluminium Electrolytic Capacitors - Leaded 220uF 50V 667-ECA-1EHG221 Aluminium Electrolytic Capacitors - Radial Leaded 220uF 25V 667-EEU-FM1V471 Aluminium Electrolytic Capacitors - Leaded 470UF 35V ELECT FM RADIAL 667-ECA-1AHG222 Aluminium Electrolytic Capacitors - Radial Leaded 2200uF 10V Bipolar: 647-UEP1H010MDD Aluminium Electrolytic Capacitors - Leaded 50volts 1uF 0.2L/S 647-UEP1C100MDD Aluminium Electrolytic Capacitors - Leaded 16volts 10uF 20% 647-UEP1C220MDD Aluminium Electrolytic Capacitors - Leaded 16volts 22uF 20% Good Luck and happy soldering! /Anders

[@corri303]

@@tukler2 Awesome! Thank you so much!

[@ETX53]

Hi, I noticed you are using a 47uF 400v cap on the power board, when the orginal value (at least on my M1) is 100uF 200v. Is that because you run it on 240V or is it simply a safe value to replace my cap? Thanks

[@tukler2]

I've checked the before pics and it's the biggest cap on the board. Korg definitely used a 47uF 400v capacitor for C11 in my synth. My Power board is KLM-1269 for 240 volt. But the schematics I've got for the KLM-1269 shows 2x100uF 200v for c11 and c12 (they are in series. The Schematics for KLM-1267 and KLM-1268 only has one cap c11 and shows the value of 100uF 200v. I'd replace with the value that Korg used on your board, since there are different revisions

[@anonymous_friend]

This is in regards to a DX7 mk1 that I recently acquired. It works fine, however I read that a capacitor in the power section can crack and catch fire. I opened up my dx7 to find that the rectangular gold capacitor is indeed cracking. So I unplugged it. Now I have received a full recapping kit from a fella on ebay, ready to do this repair myself. I've got a a decent soldiering iron with a dial temp. What temp should I run it? I've never worked on a circuit board, but made plenty of cables and minor guitar repairs. Any other tips for working with potentially charged capacitors as I fearfully attempt this? Thank you sir!

[@tukler2]

First, make sure the mains cable is unplugged. The caps should drain after a few minutes, but to be safe you could run a screwdriver over the back of the board to discharge the caps, by connecting their pins together with the screwdriver. I can’t really tell the best temperature since the dial temp on different soldering stations varies and doesn’t reflect the reality. But it should not be too hot, but just hot enough to easy melt the solder at the pins in a couple of seconds. Try to be as quick with soldering iron as possible. It might help to put some new solder on the pins before desoldering. I’d recommend that you get some old radios or other electronic equipment from the 70’s and 80’s to practice on some scrap circuit boards first. Good luck and happy soldering!!!

[@anonymous_friend]

@@tukler2 Thank you for the reply. My iron is a Weller brand, so I think it is fairly consistent with its digital temperature dial in degrees F. Can you tell me a few common mistakes to watch out for while attempting this recapping? Will too much heat melt the traces in the pcb or destroy the cap? Should I tin the pins of the new capacitors first? The caps with a specific polarity are usually labelled? Thanks!

[@tukler2]

@@anonymous_friend Too much heat will lift the traces from the pcb. There are other more heat sensitive components on the board, and the caps should be fine unless you go really hot or heat them up for a long time. The adding of extra new and fresh solder is to make the desoldering easier. You shouldn't pre tin the new caps. A common mistake is to reverse the polarity of the new electrolytic caps, or to replace with the wrong cap. Be systematic and don't hurry. Traditional lead-based solder is easier to use and have a lower melting point than the newer lead-free solder. A really good solder sucker and high quality solder wicks makes life much easier.

[@dusanljubec7203]

Thank -you , this was beautiful . I owned an M1 back in 1989 , played it for 10 yrs. Sold it , never found a keyboard as good . Just this month , purchased one from Croatia online . great shape no issues . Re-loaded the factory sounds , and it sounds new again . Since it came from Europe , it ran on 220 v, but using a regular power cord for Canada ,110v , still works fine . Will this damage my precious M1 . Do I need to do anything special .

[@tukler2]

Have you already tested it on 110 volt? It shouldn't work if it's made for 220 volt, unless it's modified. Check the labeling on the back. The only way to use an European (220v) Korg M1 in US/Canada is to plug it in to a step down transformer, or to change the power supply board. The European uses a KLM-1269, and the US/Can KLM-1269

[@dusanljubec7203]

@@tukler2 Yes , works fine ,the label says 22ov. Just wondering if I'll burn anything out.

[@tukler2]

@@dusanljubec7203 Don't run it on 110v if it's a 220v device. It'll be damaged. Be sure that it's a 220v power board inside (unscrew the bottom plate and check that the Power board is the European 220 volt KLM-1269). Then buy a step up converter www.amazon.ca/110-220-Voltage-Converter/s?k=110+to+220+Voltage+Converter They aren't that expensive.

[@dusanljubec7203]

@@tukler2 Thanks a bunch !!!That is what I was worried about . I'm defiantly taking your advice.

[@marianfotescu1808]

Thank you for the video! I'd like to repair my M1. How can I identify the correct capacitors when I order them?

[@tukler2]

Below is my list with the Mouser number, you can use it as a start. They might have replaced some with new ones, but you can use it as a start. Replace electrolytic capacitors with the same capacitance and with the same or higher voltage values. Make sure you notice which capacitors that are bipolar. There are a couple of capacitors that I had to bend slightly to fit. I think it was the 470 uF. I used 35 volts ones with a hight of 20mm. I'd probably go for a 15 mm or 16 mm instead. But I general new capacitors with the same specs are usually smaller today than they were in the 80's. I'd take all the boards out and identify all the caps and values before I make my order. 667-ECA-2CHG010 Aluminium Electrolytic Capacitors - Leaded 1.0UF 160V ELECT NHG RADIAL 667-EEU-EB1H100S Aluminium Electrolytic Capacitors - Leaded 10uF 50V 667-ECA-2GHG470 Aluminium Electrolytic Capacitors - Radial Leaded Al Lytic Cap Radial NHG Series 105C 667-EEU-EB1H101S Aluminium Electrolytic Capacitors - Leaded 100uF 50V 667-EEU-FC1H221S Aluminium Electrolytic Capacitors - Leaded 220uF 50V 667-ECA-1EHG221 Aluminium Electrolytic Capacitors - Radial Leaded 220uF 25V 667-EEU-FM1V471 Aluminium Electrolytic Capacitors - Leaded 470UF 35V ELECT FM RADIAL 667-ECA-1AHG222 Aluminium Electrolytic Capacitors - Radial Leaded 2200uF 10V Bipolar: 647-UEP1H010MDD Aluminium Electrolytic Capacitors - Leaded 50volts 1uF 0.2L/S 647-UEP1C100MDD Aluminium Electrolytic Capacitors - Leaded 16volts 10uF 20% 647-UEP1C220MDD Aluminium Electrolytic Capacitors - Leaded 16volts 22uF 20% God Luck!

[@marianfotescu1808]

@@tukler2 Thank you very much for the detailed answer. I really appreciate 🙏🏼

[@elegantmusic1986]

Great job.😃. Potentiometer model please. Thanks 🤝

[@tukler2]

If you mean the joystick potentiometer, i can't recall which one I bought, but I had to mod it to fit. You can buy the correct one here: syntaur.com/Part-3766-Potentiometer-10KB-rotary-with-center-tap

[@compaguitolo.D.T.C]

Did you buy the capacitors at Mouser? How do I identify the non-polarized ones?

[@tukler2]

They are usually marked differently with N.P. and no stripe on the minus side.

[@ACOMPA]

hi where can i buy condensateur please thanks

[@tukler2]

If you're in France you can buy them from www.mouser.fr www.distrelec.fr fr.farnell.com

[@cf9978]

I turn it up mine today and is acting very strange when i play i some keys it plays very loud others dont play it sustains notes from nothing, i swaped the battery and remains the same.... any ideias? cheers

[@tukler2]

Are the loud keys always the same keys? I'd probably clean and check the keyboard assambly and its connectors first (reseat all the contacts from the keyboard) . The "rubber" key contacts should be clean and so should the gold contacts that they press against. Weird problems could also be a result of a bad ground connection

[@cf9978]

@@tukler2 no sometimes i play the same key twice and one time it acts strange like noise or sustain and other time it plays well.

[@tukler2]

Does it play well over midi? If it does it should be a keyboard problem.

[@cf9978]

@@tukler2 i have to try it cheers mate

[@compaguitolo.D.T.C]

When should the capacitors be changed, they have never been changed on my KORG M1, if they inflate or explode, what are the consequences, do they all have to be changed?

[@tukler2]

They should be replaced if they bulge or leak. The power supply board is most critical and a failure there could cause other components in the synth to fail or burn out. On the other boards symptoms to look out for is increasing noise, or other weird behavior. They could be fine for 60 years. But keep an eye on the power supply.

[@compaguitolo.D.T.C]

@@tukler2 By the way, where can I buy the original microswitches for the M1?

[@tukler2]

You can buy them from Syntaur, Mouser, Elfa and many other places. syntaur.com/Part-3381X-Pushbutton-tact-switches-pkg-of-10

[@sam-zy2dn]

Anders thank you for this amazing video. I bought this keyboard from ebay recently and I got that the outputs have some noise when I press a key. Also the fourth output has a buzz noise on it when I just plug the cable. Could you please let me know what could be the problem or at least from where should I start the troubleshooting ! Thank you so much. Iaf jag bor i Stockholm och det blir undebart att ha kontakt Anders! tack förehand :)

[@tukler2]

Hej, Sam! First of all the M1 has some noise by default. The effects are noisy and you can hear aliasing caused by the low sample rates. But that is obviously not your problem. When troubleshooting, go for the simple things first. Visually inspect the boards an make sure that everything looks OK, there are no damages, and that no capacitors are bulging or has has leaked. Unplug and re-plug all the cables to make sure that the cables are providing good contact.I’d start with the jack board and go backwards from there. Following the signal path. Buzzing and weird problems are often caused by ground problems. Check with a multimeter on the Ohms- or continuity setting that the ground path has no resistance. You’re given good clue to start the troubleshooting with he buzzing on the forth output, try to find what differs from the other outputs, including the headphones.The problem should be on the analog signal path. So follow the signal from the Jack board to the DAC-board (KLM-1261). The signal goes from the DAC- board -> Gain control -> Filter -> Where it splits. The outputs 3 and 4 goes directly to the outputs. The 1 and 2 to the Master volume and then to the outputs. Headphones goes to Master volume and then to the headphone amp before the headphonejack. I you don’t have an oscilloscope you can make an audio probe connected to small amp and use your ears to hear were the noise is introduced in the signal path. To make the probe take an ordinary mono audio cable with no plug on one end. Put an alligator clip on the ground wire (and connect it on a good ground point in the synth) solder a capacitor on the audio wire and use the free leg of the capacitor as a probe. You can then probe around and follow the audio backwards in the path. The capacitor lets the AC audio through and stops the harmful DC voltage. I use an ordinary electrolytic capacitor. Make sure that you don’t touch any of the live voltage parts, and that you don’t short out anything when working with the synth open. Use an ESD-bracelet to make sure not to destroy anything with static electricity. Lycka till!

[@sam-zy2dn]

@@tukler2 Thank you for precise and amazing descriptions. I was checking internet and I saw that Korg Kroma has exactly all the sounds of Korg M1. It is not wise I return the M1 back and go for Kroma? It looks most of M1s have some issues as they have been used for many years. It cost me 213 EUR to get this keyboard that suppose it works perfectly. I also found the key after touch and master tuning does not work too.

[@tukler2]

It might be wise to go for the Kroma. This M1 seems to have some issues and it's probably not worth it, unless you do it as a projekt for the fun of it.

[@sam-zy2dn]

@@tukler2 I want to buy a ground isolator lifter to test if the problem is for the ground. I asked from Kjell and they did not have it. In generally what do we call such adapter in Swedish? thanks

[@tukler2]

I'll do it in swedish. Ojordat, men det kommer inte hjälpa dig. Det är kontakten till jord någonstans inne i synthen kan vara problemet. Då måste man skruva isär, mäta inuti på kretskort och kontakter med en multimeter när synthen är frånkopplad från elnätet.

[@compaguitolo.D.T.C]

friend, I hope you are well, I just had a problem with my Korg M1 when I play, the sound comes out clean but at the same time it comes out blurry, what could it be?

[@tukler2]

I haven't had this problem and I don't really understand what it sounds like. But for troubleshooting I'd check the different outputs separately to see if it's related to any specific output. Headphone, 1/L, 2/R, 3, 4. I'd also check if it's present with the effects turned off

[@compaguitolo.D.T.C]

@@tukler2 In fact, if you remove it it lasts a few minutes and it comes back normal. Wouldn't it have anything to do with the power board? from some condenser

[@tukler2]

Yes. It could be a condenser there, or somewhere else. To be sure you'll need an oscilloscope and probe around. Or do a shotgun repair and replace them all. The power supply is the one that could cause most damage if it's faulty.

[@compaguitolo.D.T.C]

@@tukler2 In fact, the transitor of the 3-pin power board I see that it gets hot enough. Is that normal? And what is the shotgun and the oscilloscope

[@tukler2]

I can't say how hot the transistor will be under normal conditions. But they shouldn't be too hot to touch if they don't have a heatsink. An oscilloscope is a device that visually displays and measures waveforms of voltages and audio. You can then probe around on the boards check for anomalies. The shotgun method is to not bother finding the specific faulty component, but to change them all in hope of also replacing the one causing the problem.

[@sureshambalayam2720]

Where can I get the sound card and the song card.

[@tukler2]

Try Ebay for the cards. If you need to store patches and sequencer data you can use a computer and save them as syseq data. You can also find loads of patches on the Internet.

[@dav1dbone]

Are the 01w tact switches the same part number?

[@tukler2]

They should be the same, though Korg have different part numbers in the service manuals. Syntaur sell the same switches to both synths

[@leonelchavez6747]

What the call that black looking like a pencil is like a welding thing ?

[@tukler2]

It's a soldering Iron, for soldering the components.

[@dpsynthtutorials1757]

I just bought this amazing machine secondhand and its in very good condition, but all the presets are distorted and the sound wobbles. Almost like digital distortion. I tried to do a factory reset and install all patches again but the sound is still distorted. I also changed the battery and checked all the cables, condensers, fuses etc. on the circuit boards visually, but could not see anything strange like leaking or blown up caps, burnt resistors. What could be wrong? Would love to get this legendary synth working poperly.

[@tukler2]

Looks like you have some trouble shooting ahead of you. First I'd check that if the distortion is the same on all outputs. Then I'd trace the audio signal back on the PCB's with a oscilloscope or an audio probe (something like a small battery powered audio amp with one lead connected to audio ground and probing through a capacitor to prevent DC from getting into the amp). Just try to find where the distortion is introduced, If it's in the analog part of the circuit. Make sure you stay safely away from the mains part and don't cause any short circuits and only follow the audio route.

[@pshimmons]

So how long did all that take you?!?

[@tukler2]

The footage is 3½ hours, it's not the first time I've taken an M1 apart. I'd say I'd do it in aproximately 3 hours.

[@papahdod9798]

Some of tooths are die, what should I do?

[@tukler2]

D&D Plus I don’t know what you mean with “tooths”, but I understand that they are dead and don”t work.

[@papahdod9798]

@@tukler2 some keys are dead in the same pattern

[@tukler2]

First I'd check that the ribbon cables from the Keyboard scanning matrix to the main board are intact. Then I'd reseat the contacts to make sure that they have a good connection. If that doesn't fix it I'd check continuity with a multimeter beeper. And then troubleshoot the actual diode matrix, which can be a bit tricky to figure out.

[@andrewletsoalo6661]

Hi my m1 workstation it can't be powered.

[@tukler2]

I'd start with checking the Power supply board. First do a visual check to see if there's anything looking suspicious like bulging or leaking capacitors, burnt components. Then I'd check the fuse. After that I'd power it up and measure the voltages going out, to see if they are what they're supposed to be.