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Aegis
Joined: 17 Jul 2014
Posts: 14
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 Posted: Sun Jul 28, 2019 2:10 am Post subject: Korg X50 dead? |
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Today when I was playing my X50, it suddenly shut down and wouldn't power up again. The external power supply is fine, powers up other boards with similar power ratings. No heat or sounds of anything breaking were noticeable, the board just powered down.
Before the power plug and the associated board has been replaced on the X50. The board is my primary suspect. Any ideas on how to diagnose whether the it is working correctly?
I would rather order the replacement parts (if still available), so I am very thankful for advice in diagnosing the issue. |
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voip
Platinum Member
Joined: 27 Nov 2014
Posts: 3769
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| Posted: Sun Jul 28, 2019 4:04 pm Post subject: |
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The first thing to check would be the power supplies coming from the KLM-2679 board. On the multiway connector, there should be +11.5V, +5V and 3.3V on pins 1,2, and 3 respectively, relative to pins 4,5,6, which are ground. If these voltages are correct, then suspect the main board.
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Aegis
Joined: 17 Jul 2014
Posts: 14
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| Posted: Sun Jul 28, 2019 8:57 pm Post subject: |
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| voip wrote: | The first thing to check would be the power supplies coming from the KLM-2679 board. On the multiway connector, there should be +11.5V, +5V and 3.3V on pins 1,2, and 3 respectively, relative to pins 4,5,6, which are ground. If these voltages are correct, then suspect the main board.
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Thanks a ton, very useful. Will check on the board tomorrow. |
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Aegis
Joined: 17 Jul 2014
Posts: 14
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| Posted: Tue Jul 30, 2019 2:58 pm Post subject: |
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| voip wrote: | The first thing to check would be the power supplies coming from the KLM-2679 board. On the multiway connector, there should be +11.5V, +5V and 3.3V on pins 1,2, and 3 respectively, relative to pins 4,5,6, which are ground. If these voltages are correct, then suspect the main board.
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Al right, I checked the board and the output is approximately as described, so it it must be something else then. Is there similar straight forward intel on the main board? |
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voip
Platinum Member
Joined: 27 Nov 2014
Posts: 3769
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| Posted: Tue Jul 30, 2019 8:07 pm Post subject: |
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To fully investigate the main board would require specialist test equipment and detailed information not divulged by Korg.
Does the LCD backlight come on?
If so, with the power switch off, keep the <ENTER> and <0> keys pressed whilst turning on the power, and keep them pressed for a few seconds more. This procedure would normally initialize the X50 and load the factory preload data, so there is a chance it might work if the X50 shut down was caused by a memory glitch.
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Aegis
Joined: 17 Jul 2014
Posts: 14
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| Posted: Tue Jul 30, 2019 10:55 pm Post subject: |
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| voip wrote: | To fully investigate the main board would require specialist test equipment and detailed information not divulged by Korg.
Does the LCD backlight come on?
If so, with the power switch off, keep the <ENTER> and <0> keys pressed whilst turning on the power, and keep them pressed for a few seconds more. This procedure would normally initialize the X50 and load the factory preload data, so there is a chance it might work if the X50 shut down was caused by a memory glitch.
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The LCD is completely blank as far as I recall. All other lights off as well, no sign of any life. I would not like to initialize the board, since it has patches that have not been backed up, a reason why it would be nice to get it to function.
I also took a look at the main board, visually no signs of damage. Do you believe it's viable to disconnect everything apart from power from the main board and check the voltages on the connectors? It's possible that the fault lies somewhere deeper, some liquid was spilled on the location of the knobs a long time ago, one of the knobs doesn't work. But before digging deeper it would be at least nice to know the power supplied from the main board works, this seems like a power issue to me. |
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Aegis
Joined: 17 Jul 2014
Posts: 14
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| Posted: Tue Jul 30, 2019 10:55 pm Post subject: |
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| voip wrote: | To fully investigate the main board would require specialist test equipment and detailed information not divulged by Korg.
Does the LCD backlight come on?
If so, with the power switch off, keep the <ENTER> and <0> keys pressed whilst turning on the power, and keep them pressed for a few seconds more. This procedure would normally initialize the X50 and load the factory preload data, so there is a chance it might work if the X50 shut down was caused by a memory glitch.
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The LCD is completely blank as far as I recall. All other lights off as well, no sign of any life. I would not like to initialize the board, since it has patches that have not been backed up, a reason why it would be nice to get it to function.
I also took a look at the main board, visually no signs of damage. Do you believe it's viable to disconnect everything apart from power from the main board and check the voltages on the connectors? It's possible that the fault lies somewhere deeper, some liquid was spilled on the location of the knobs a long time ago, one of the knobs doesn't work. But before digging deeper it would be at least nice to know the power supplied from the main board works, this seems like a power issue to me. |
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voip
Platinum Member
Joined: 27 Nov 2014
Posts: 3769
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| Posted: Wed Jul 31, 2019 6:21 pm Post subject: |
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The reason for asking about the LCD backlight is that it receives its power directly from the 5V supply, not relying on a processor or other device pin from turning on. If 5V, give or take a few percent, is present on the power board output connector pin 2, but the LCD backlight doesn't come on, then there is a break in the circuitry, somewhere between the power supply board and the LCD.
Liquids with electrical current passing through them can quickly become quite a corrosive environment, cutting through PCB tracks quite easily after a spillage, if the power is not turned off. It would be worth investigating where the spilt liquid might have flowed, and investigate those areas more closely.
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Aegis
Joined: 17 Jul 2014
Posts: 14
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| Posted: Thu Aug 01, 2019 1:02 am Post subject: |
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| voip wrote: | The reason for asking about the LCD backlight is that it receives its power directly from the 5V supply, not relying on a processor or other device pin from turning on. If 5V, give or take a few percent, is present on the power board output connector pin 2, but the LCD backlight doesn't come on, then there is a break in the circuitry, somewhere between the power supply board and the LCD.
Liquids with electrical current passing through them can quickly become quite a corrosive environment, cutting through PCB tracks quite easily after a spillage, if the power is not turned off. It would be worth investigating where the spilt liquid might have flowed, and investigate those areas more closely.
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Thanks again voip, I will check on it again tomorrow, very useful! |
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Aegis
Joined: 17 Jul 2014
Posts: 14
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| Posted: Thu Aug 01, 2019 1:05 pm Post subject: |
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| voip wrote: | The reason for asking about the LCD backlight is that it receives its power directly from the 5V supply, not relying on a processor or other device pin from turning on. If 5V, give or take a few percent, is present on the power board output connector pin 2, but the LCD backlight doesn't come on, then there is a break in the circuitry, somewhere between the power supply board and the LCD.
Liquids with electrical current passing through them can quickly become quite a corrosive environment, cutting through PCB tracks quite easily after a spillage, if the power is not turned off. It would be worth investigating where the spilt liquid might have flowed, and investigate those areas more closely.
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Okay, I took off the main board and the LCD. The LCD board looked fine, I put it back for now.
The back side of the main board has some gluey substance all over the place, also there was a small piece of dust between the LCD connector and the adjacent conductor. Not sure if any of this is relevant.
Edit: Highly unlikely that there has been any short circuits, I can't even get a resistance reading off components because of the coating. I disconnected everything from the board, and the connector that is connected to the LCD on the main board (KL8A) shows approx 0.7 volts relative to ground on all pins except 4,7 which are 0V. At least voltage is delivered to most of the connectors, hard to say if there is a fault. |
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voip
Platinum Member
Joined: 27 Nov 2014
Posts: 3769
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| Posted: Tue Aug 13, 2019 12:54 pm Post subject: |
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| The gluey substance doesn't sound right and probably shouldn't be there. Could it be leftover from a spillage? The only alternative is some sort of conformal coating to protect the board from high humidity, though Korg don't generally apply such a coating to their boards. |
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