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Korg 01R/W Hum Rackmount Synthesizers
Old 19th December 2010
  #1
Gear Head
 

Korg 01R/W Hum

Good day!

I've got a problem with a Korg 01R/W synth module, it hums when on. The high pitch noise comes from the transformer circuit, if that is the correct way to name it.

Here are some pictures:





And the front panel LCD is very dim even at the brightest setting.




and a mp3 of the noise:
https://www.gearslutz.com/board/attac...1&d=1292759864

Anybody have an idea what could be wrong with the transformer circuit and how it could be fixed?

thanks in advance

Trey
Attached Thumbnails
Korg 01R/W Hum-img_0586.jpg   Korg 01R/W Hum-img_0585.jpg   Korg 01R/W Hum-img_0589.jpg  
Attached Files

KORG 01RW HP Noise.mp3 (293.3 KB, 705 views)

Old 24th December 2010
  #2
Gear Nut
 

just change backlight or replace lcd to led and turn off inverter (usually in metal box)

this pitch comes not from transformer but from inverter

inverter is unit for generating high voltage needed for lcd backlight

when backlight is dim inverter generates pitch
Old 25th December 2010
  #3
Lives for gear
 
acreil's Avatar
 

An EL panel degrades over time; its impedance increases and this can result in a buzzing sound from the inverter (which supplies high voltage to the EL backlight), and possibly glitches or crashes if it starts to interfere with rest of the circuitry.

You can either replace the EL backlight (which will still fail eventually) or install an LED backlit display, in which case you'd want to disable the inverter. Probably removing the transformer marked TA042 would suffice.

Here's a replacement display: SYS77/99 Replacement LCD Display

I've installed two of these (in a TG77 and K2VX) with great results. It isn't fun but it's doable if you're careful and patient. You'll have to solder it in and maybe install a new connector. You'll also need to find a 5V power source to drive the backlight, and maybe do some mechanical modifications so that the new display will fit (it's probably larger than what's in there now).
Old 6th January 2011
  #4
Gear Head
 

Quote:
Originally Posted by KovalStudios View Post
just change backlight or replace lcd to led and turn off inverter (usually in metal box)
Would I need the schematics for the synth to know where to turn it off?

If I do install a new LCD, would that guarantee that the inverter would stop humming?
Old 6th January 2011
  #5
Gear Head
 

Quote:
Originally Posted by acreil View Post
You can either replace the EL backlight (which will still fail eventually) or install an LED backlit display, in which case you'd want to disable the inverter. Probably removing the transformer marked TA042 would suffice.

Here's a replacement display: SYS77/99 Replacement LCD Display
Hmm, I don't have the schematics, I'm not sure what I would do if the LED display had more or less connections than the normal one. Or are they all standard with the same number of connections (the holes on the sides of the display)?

Would I need a very good soldering iron with a sharp tip? The one I have now has a range from 0 to 450 degrees Celsius and a thin but not so thin tip.
Old 7th January 2011
  #6
Lives for gear
 
acreil's Avatar
 

The display format is standard. You'll just have to do something about the connector, which is probably soldered onto the original display. See if header pins and an IDC connector will fit. Soldering it isn't tricky. It's only difficult if you stupidly try to reuse the original connector. It's far more mechanical than electronic.
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