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how to recognise a MKS30 failed chip
Old 15th September 2010
  #1
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mamonu's Avatar
 
🎧 10 years
how to recognise a MKS30 failed chip

Problems with your MKS30?

Here is a list of typical 80071a symptoms:

  • Erratic or sudden loud noise from synthesizer output, particularly after 10 minutes of powering up.
  • Note hang-ups or long sustain.
  • One synth voice will not respond to filter or amplifier changes.
  • Unstable operation.
You most likely have a failed 80017a VCF/VCA chip.

However unlike Juno106 there are no Service Modes or anyhting that might help you recognise which of the
80017a chips are problematic

There are six summing resistors used to combine each voice . The resistors bridge across the voice section to the output section.

If you are not sure which voice is causing a problem, you can use a scope to see the VCF/VCA output by touching the left side of each resistor.

If you do not have a scope, then attach a wire to chassis ground, and then touch the wire to the left side of each resistor. This will mute the output of the synthesizer voice. When you mute the output of the bad VCF/VCA, the erratic sound should stop.
(see pic attached)






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how to recognise a MKS30 failed chip-picture-422.jpg  
Old 24th September 2010
  #2
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dougt's Avatar
 
🎧 10 years
Quote:
Originally Posted by mamonu ➡️
Problems with your MKS30?

However unlike Juno106 there are no Service Modes or anyhting that might help you recognise which of the 80017a chips are problematic
This is not true. There IS a service mode in the MKS-30 that shows the voices being playing on the display. It's in the service manual. I'll try to find mine and post back.
Old 23rd October 2010 | Show parent
  #3
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mamonu's Avatar
 
🎧 10 years
Quote:
Originally Posted by dougt ➡️
This is not true. There IS a service mode in the MKS-30 that shows the voices being playing on the display. It's in the service manual. I'll try to find mine and post back.


please do. the only Service Manual contents i have seen on the internet are some scans of the schematics.
Attached Files
File Type: pdf mks30schematics.pdf (286.9 KB, 382 views)
Old 29th October 2010 | Show parent
  #4
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dougt's Avatar
 
🎧 10 years
Quote:
Originally Posted by mamonu ➡️
please do. the only Service Manual contents i have seen on the internet are some scans of the schematics.
As promised -

To put the MKS-30 into test mode, while holding MIDI Ch button press Dynamics button. The display will then show the current voice being played as a long line like this -

, , l , , ,

which would indicate voice 3 is playing.

Oh and you can use the front panel buttons 1 to 8 to play the synth in the mode by holding down MIDI Ch and pressing the 1 thru 8 buttons (1 is C and 8 would be C an octave up).
Old 29th November 2012 | Show parent
  #5
Here for the gear
 
🎧 5 years
thanks, and after tuning-test mod we need some calibrated voice, but how?
gain calibrated its not hard, but fiter and reso...
on front panel keys 1,2,3,4... its presets for calibration ? saw, pulse, ... in 5,6 not sound, but its need for DC ball ????????.

need help! how calibrate reso Filter ?

??? ????? ? ????? ??????? (?? ???? ???? 8 ????????????? ????????) ? ??? ???????-???????????. ????? ??? ??????? ????????? ????????? ? ?????? ??????? ??? ?????? ??????.

Relly need servise manual
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