I've triple checked and unfortunately that not a connection problem after desoldering/soldering. Thank you.
I need to find the chip that tell the voices to play or to be silent.

I've repaired a few Juno-106 but on this one it's hard to find the fault culprit. The fault is that even with all waveform off and sub off too i can hear a sort of saw at 60% of the normal volume. It's a bit like a DCO bleed that we should not hear when none wavform is ON. When the waveform are ON t...

If you have not modified the midi files, i would suggest a MIDI filter that just let pass only notes, then check if it works like this. If yes let pass more MIDI events until it crash again. Are you sure you've got one more machine since the last set up? All the machines connected in midi could had ...

Fortunatly it works when you come from google

What is the general frequency of your 6VPP sine wave you're seeing on U230 6&7? Does it match the signal seen on U230 pin 2? The sine is 840khz at start and slowly speed down. No it do not match the signal seen on U230 pin 2. I would expect failure of the 1N914 or 100 pF cap at U230 pin 2 could be ...

Pins of U230 measure out as follows: Pin 1: waveshape, picture attached. Pin 2: common/no voltage Pin 3: common/no voltage Pin 4: -15 volts (yay!) Pin 5: -5 volts Pin 6: -5 volts Pin 7: -5 volts Pin 8: +15 volts Ok thanks a lot i'have double checked and here is what i measure: Pin 1: waveshape (not...

Crochambeau, did you finnaly repaired your machine? Is it possible you measure U230 pins?
I'am a bit lost now.

I feel like there is a very low chance that part would be running hot to the touch if everything was operating normally, that part is rated at 25 mA per channel output. Replacing that dual opamp might be the trick. I read data on U226-4, and the schematic corroborates that as a data line. Might be ...

Also checked all data bus line, they are all the same on ech IC of the Data Bus. I still feel that U230 is very hot. What kind of measure do you have on your machine on U226 and U230? Here is what i measure: U226 DAC: Pin 1= two 4V Pulses Pin 6= 4VPP Data line Pin 11= 4VPP Data line Pin 16= 800mvPP ...

I took down a list of parts you have replaced, I notice in your first post you typed U216 twice in the first declaration of work done. Typo? Or is there another part that has been reworked? Yes, i've also replaced U218. I've just replaced U230 AOP without success ( there where no strange measures b...

Remind me, do you have the full range of sound tuning via MIDI external control? Or just the levels you now have at your fingertips? No, i don't have the full range via MIDI, i just have exactly the same levels as with the potentiometer. You indicate you see the tune/vol range from 00 to 15 on pane...

I've replaced U225 and it is better but still faulty: Now the display indicate number of setting from 00 to 15 when i move the TUNING or VOLUME pot; but i can hear only two different tuning on the bass, two different tuning on the snare. On most other sounds i can hear only 3 or 4 different tuning, ...

There is nothing on U225 (74LS221) pin 5. So there are great chance it is the culprit? Do you see two pulses on your machine? Also it looks like U225 is related to the metronome, then it may be also the culprit of the second problem i have on the machine concerning metronome missing beats. I'm going...

There is a pulse about 100 μs long, volume adjusts the pulse height, tuning adjusts the background DC level the pulse rides on. At least, that's what my machine does - please bear in mind that my machine is also malfunctioning - but the voice tune and volume were working last time I used it. Anyway...

Got a scope, but didn't found evidence of fault so replaced some integrated circuits of the individual tuning that i had under the hands.
My question:
How to check with scope if the 4053 is switching? Or if it is latched?