M50 Not Responding!

Rishat · Post by **Rishat** » Sun Jun 20, 2010 10:07 am

Dear Folks.. I have just experienced a very scary problem!! Last night when I turned on my M50 as a I do everyday, only the joystick light lit up and nothing else.. No sound.. No display and nothing!! After turning on and off several times it finally turned on and worked fine... After one hour I switched it off and on again and the same problem persist...!!! After 30 minutes of playing I turned it off and after two hours I switched it on and this time it turned on without any bug.. Note that I am using firmware version 1.1.0.. One more thing to share I often get electric shock when I touch the back panel (just beside the on/off switch) of my M50.. I am using a Prolink 600VS (http://www.prolink.co.id/products/pc600.htm) UPS (Uninterrupted Power Supply) to avoid malfunction of my machine during power surge as it has been suggested by the forum members... Any suggestion??

mocando · Post by **mocando** » Sun Jun 20, 2010 3:18 pm

Jeez Akram, what I don't like is that electric shock you mention. You definitively gotta fix that or you're risking something worse. I'd check the power supply if is passing to the M50 the right voltage. Get yourself a voltmeter and check that out first.
Second, is the M50 in a specially cold (air conditioned) and dry place with carpeting that strong static could be generated?

candlewick · Post by **candlewick** » Sun Jun 20, 2010 6:04 pm

I get the "not responding" once in a while when i power my keyboard rig up. in many cases, all I have to do is cycle a patch number up then back and it's back to normal. i'm suspicious that powering two boards up at the same time with midi cable connected has something to do with it. I never emperience this when the M50 is being used as a stand alone.

kimu · Post by **kimu** » Sun Jun 20, 2010 7:15 pm

have a look to this thread also:

http://www.korgforums.com/forum/phpBB2/ ... hp?t=52474

http://www.korgforums.com/forum/phpBB2/ ... hp?t=52220

mocando · Post by **mocando** » Sun Jun 20, 2010 9:24 pm

Candlewick: Having two boards connected via midi has nothing to do with that. I have 3 keyboards all powered thru the same power strip, all connected via midi thru a MOTU Micro Express midi merge box and I have never experienced such behavior. Maybe somehow there is a slight power flow reaching the midi ports, maybe a bad cable, power outlet not properly grounded, etc. In short, power MUST be clean in order to avoid any issues like that.
For what Rishat is telling us, there is some power leaking on the case of the board. I don't know if he uses midi cables, but it should be something else. And using an UPS is no safe measure, unless the power is fed to the appliances FROM the battery and not from the external power even if there is no power outage. That way the UPS will filter any unwanted power spikes and instabilities in the power flow.

kimu: I think Rishan and Candlewick's issues are not the same. The links point to a known issue on some boards freezing once they are up and running, and sometimes holding a note. That is not what's happening here, they cannot power up their M50 but in a few tries.

Definitively should be a power issue. You might want to contact an electrician to do some testing of your power installation at your studio. Check for:

- Grounding
- Power on the neutral or ground wires (even if is a small amout). Any power flowing thru neutral or ground is bad. Even if is single digits.
- Overall stability of the voltage. Ir should be between a range that electricians know, maybe 100 to 130 for 120 volt devices and 210 thru 230 for 220 volt sites. I don't know exactly, but they should.

Rishat · Post by **Rishat** » Mon Jun 21, 2010 5:52 am

Dear Martin and Others: Thanks so much for your valuable input. Here are the technical specifications I am getting from the power source:

# Input

* Phase: Single+GND
* Voltage Range: 160-275V
* Frequency: 45-65 Hz

# Output

* Voltage: 220V AC (±5%)
* Waveform: Square Wave
* Frequency: 50HZ±1% or 60HZ±1%
* Transfer Time: 2ms typical

# Surge

* Energy Rating: 320 Joules Instantaneous Response
* Test Standard: IEEE 587 Cat. A&B

# Noise Filtering: EMI/RFI Full Time Suppression

# General

* Noise: <45dB
* Temperature: 0ºC -40ºC
* Humidity: 30%-90%
The electric shock I have mentioned is not a 220V shock its quite lower than that I can feel and tolerate it. Let me elaborate a more about my power setups:

1. I am using a 2 pin multiplug with a fuse installed inside it and connected my UPS with it.

2. There are 2 outputs of my UPS. I have connected the M50 with one and my Speaker with other. All the connections I am using are of 2 pins.

3. I am using a standard wooden keyboard stand.

4. I am using a standard MIDI cable to connect my M50 with my Laptop (Though most of the time I use my M50 as a standalone machine) and a Damper pedal.

I have checked my power source with a voltmeter and I am getting full 220V.. So whats the catch? Is it the 2pin plug or the grounding issue? I do I make sure that my supply is fully grounded.. Thanks in advance!!

mocando · Post by **mocando** » Mon Jun 21, 2010 1:59 pm

Hmm, I can't help you too much further, I can only point you the way, I think you better ask an electrician which could help you better.

Having said that, and if you want to be sure you are not having issues with your board and finally blame the power installation, I would recommend a power inverter. Just get a standard 12 volt power adapter and an inverter. Check here:

http://www.voltageconverters.com/220_vo ... rters.html

That way the power goes from the 220 volt outlet (with suspicious power quality) to 12 volt DC, and then from 12 volt DC back to 220 volt AC but generated by the inverter, and completely isolated from any power issue on the wall. That is the cleanest most stable power you can get.

I would ask an electrician anyway.

Hope it helps.

X-Trade · Post by **X-Trade** » Mon Jun 21, 2010 2:03 pm

Rishat wrote: 3. I am using a standard wooden keyboard stand.

I've never heard of or even seen a wooden keyboard stand, let alone consider one 'standard'.
However I'm thinking that could cause a problem as your equipment would not be earthed to the ground if there is an electrical fault - instead it will try to earth through you when you touch the metal!

That said, some of my equipment sits on a wooden desk....

Rishat · Post by **Rishat** » Tue Jun 22, 2010 3:53 am

X-Trade wrote:
Rishat wrote: 3. I am using a standard wooden keyboard stand.
I've never heard of or even seen a wooden keyboard stand, let alone consider one 'standard'.
However I'm thinking that could cause a problem as your equipment would not be earthed to the ground if there is an electrical fault - instead it will try to earth through you when you touch the metal!

That said, some of my equipment sits on a wooden desk....

I am talking about this one (http://www.google.com/imgres?imgurl=htt ... s%3Disch:1)

Thanks Martin you are awesome as always.. I will try the converter, hope that will solve the problem.. And the grounding issue as Xtrade wrote.. I will solve the problem as well (I think I need an electrician for that) I will let you know the status... Thanks for all your help..!!

alec118 · Post by **alec118** » Sat Jul 03, 2010 7:22 am

Kinda coming into this a little late, sorry.

But anyways, here's my two cents. I would agree that the source of power might be an issue, however the electric shock makes me think otherwise. Rishat wrote that he was being shocked by a non-220 volt current suspiciously close to the power input. The power being sent to the M50 by the power supply is 12 volt (I think.) So, that would be a fairly low voltage shock if one were to receive it. Therefore, I think that this 12 volt power is being leaked into the board somewhere inside it. This would mean a defective circuit or something inside his M50, therefore a problem separate from grounding/dirty power. So, my suggestion would be to contact Korg Services about a faulty board.

That's my opinion. I could be totally off

though, so I'd try everyone's suggestions.

xmlguy · Post by **xmlguy** » Sat Jul 03, 2010 10:47 am

Dry skin has a dielectric resistance that usually requires about 48V or higher to feel a shock. The shock hazard described by the OP is certainly higher than 12V DC. You should stop using the UPS on that circuit immediately. There is something wrong with the power circuit or UPS that is allowing a ground loop shock hazard. This could kill you or a family member if the shock is allowed to travel through the chest area, causing the heart to go into fibrillation at 50/60 cycles per second. This does not require excessive voltage to cause death.

Don't mess with electricity shock hazards unless you know what you're doing. Get an electrician to identify the problem. This could save your life. You should never be receiving a shock when touching your keyboard, never. The fact that you are indicates a very serious problem somewhere in the power circuit, UPS, or power supply. It is likely that there is some short circuit or floating grounding problem that hasn't been detected yet. You don't want to have the exact problem detected after someone finds a person killed due to electricution. But unfortunately, that's often how people find out because so many people ignore shocks and continue to "try things" to figure out the problem without understanding the risks.

alec118 · Post by **alec118** » Sun Jul 04, 2010 2:15 am

You should never be receiving a shock when touching your keyboard, never.

Agreed, definitely. xmlguy, you seem to know what you're talking about way more than I do.

I think the OP should definitely take your/mocando's advice and call an electrician ASAP. This seems like a great danger, and definitely should not be blown off.