Korg 01wfd turn off and no power again! What is this?

[Riva Lima]

Helo! I was playing normally here at home, and the keyboard just turned off on its own, and didn't turn on again! When I press the power button, it is possible to hear the noise that it was turned on, through the audio output, but that's it ... no LEDs, no display, like dead ... has anyone seen this happen ???
Best regards

[T3owner]

Possible cause is a common 01/W problem, leaking electrolytic capacitors.

See https://hajo.kessener.net/electronics/k ... nd-repair/

[Riva Lima]

Possible cause is a common 01/W problem, leaking electrolytic capacitors.

See https://hajo.kessener.net/electronics/k ... nd-repair/

I made noew some voltage measurements on the input pins of the CN21A connector, and I noticed that when turned on, the voltages are very low, they are no more than 2v each ... I think it is the transformer!

[Riva Lima]

I think the culprit of my 01wfd not power, is the transformer ... I measure the 5 output pins that go to the psu board, which must be 12v, -12v, 5v and 2 ground ... and no result of these when it it's power on

[the_crimson_thunder]

Have you already checked the 3 fuses on the power supply board?

Depending on your mains voltage those fuses are:

110V - 120V:
FU2 &FU3: 1,5A slow blow
Fu4: 6,3A slow blow

220V - 240V:
FU2 &FU3: 800 mA slow blow
Fu4: 3,15A slow blow

And don't forget to check the mains fuse FU1 as well:

110V - 120V:
Fu1: 830 mA slow blow

220V - 240V:
Fu1: 250 mA slow blow

Since it is no switching mode psu I highly recommend to disconnect ALL boards from the psu to see if there may be a shortcut anywhere that may cause this issue...

[Riva Lima]

Here, some measurements! Fuses, none are broken... and tested the disconnected psu from the board ... I checked the floppy connector on the board, if it was sending the 5v, and no ... it's not

https://youtu.be/TVZhX8bXn38

[the_crimson_thunder]

Judging from your video: you don't measure correct! That connector goes straight to the transformer where the output voltages are AC! But your meter is set to DC!

Related to your video you have (from right to left) the colors:

red - black - red (for generatiing +12V / -12V)

and

black(?) - blue (for generating +5V)

Set your meter to 200 V~, connect the red lead to the 'first' red wire (right side), the black lead to the black wire (2nd) - note the voltage on a paper or so. Keep the black lead connected and move the red lead over to the 2nd red wire (3rd from the right) and also note the shown voltage.

Now take off both leads, leave the meter to how it's set and now connect the black lead to the black wire (2nd from the left side), the red lead to the blue wire (1st from the left side) and note that measure. Please come back with the results...

[Riva Lima]

Judging from your video: you don't measure correct! That connector goes straight to the transformer where the output voltages are AC! But your meter is set to DC!

Related to your video you have (from right to left) the colors:

red - black - red (for generatiing +12V / -12V)

and

black(?) - blue (for generating +5V)

Set your meter to 200 V~, connect the red lead to the 'first' red wire (right side), the black lead to the black wire (2nd) - note the voltage on a paper or so. Keep the black lead connected and move the red lead over to the 2nd red wire (3rd from the right) and also note the shown voltage.

Now take off both leads, leave the meter to how it's set and now connect the black lead to the black wire (2nd from the left side), the red lead to the blue wire (1st from the left side) and note that measure. Please come back with the results...

Okay, miraculously, it went back to work, but now it's a few seconds on and off by itself ... transformer?

https://youtu.be/bGtF_8a6nsw

[Riva Lima]

Judging from your video: you don't measure correct! That connector goes straight to the transformer where the output voltages are AC! But your meter is set to DC!

Related to your video you have (from right to left) the colors:

red - black - red (for generatiing +12V / -12V)

and

black(?) - blue (for generating +5V)

Set your meter to 200 V~, connect the red lead to the 'first' red wire (right side), the black lead to the black wire (2nd) - note the voltage on a paper or so. Keep the black lead connected and move the red lead over to the 2nd red wire (3rd from the right) and also note the shown voltage.

Now take off both leads, leave the meter to how it's set and now connect the black lead to the black wire (2nd from the left side), the red lead to the blue wire (1st from the left side) and note that measure. Please come back with the results...

Here is... And now I’m hearing that screeching noise probably coming from the 25v 6800uf capacitor

[the_crimson_thunder]

Those voltage values are all ok! I don't think that the transformer is faulty. Are those voltages you've measured still present if the synth 'switches off by himself'? Or only when in working order?

If they're present under both conditions the problem lies 'behind' the transformer.

If that issue shows up again I recommend to disconnect the 'outgoing' connectors from the psu - connection to the main board (CN4B), to the floppy drive (CN7A) and to the LCD FL (CN16A) while checking the voltages. Only one connector after the other to see if any of the voltage's values are fluctuating in a larger amount.

[Riva Lima]

Those voltage values are all ok! I don't think that the transformer is faulty. Are those voltages you've measured still present if the synth 'switches off by himself'? Or only when in working order?

If they're present under both conditions the problem lies 'behind' the transformer.

If that issue shows up again I recommend to disconnect the 'outgoing' connectors from the psu - connection to the main board (CN4B), to the floppy drive (CN7A) and to the LCD FL (CN16A) while checking the voltages. Only one connector after the other to see if any of the voltage's values are fluctuating in a larger amount.

I will check it, thankyou very much!