Juno-106 Restoration story/Power Supply woes
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Re: Juno-106 Restoration story/Power Supply woes
Poly 1 selected in tezt mode so all voices sound at once, too?
Herrare umanum est.
Re: Juno-106 Restoration story/Power Supply woes
Nvm, you got another calibrated unit which is flawless. Damned.
Herrare umanum est.
Re: Juno-106 Restoration story/Power Supply woes
I can only recommend to learn oscilloscope basics to monitor the dac and processor behaviour and compare with the healthy unit.
I might get back to this irritating thing if I remember of anything barely useful.
I might get back to this irritating thing if I remember of anything barely useful.
Herrare umanum est.
Re: Juno-106 Restoration story/Power Supply woes
Unfortunately, my oscilloscope is a puny Jyetech DSO shell.Mooger5 wrote:I can only recommend to learn oscilloscope basics to monitor the dac and processor behaviour and compare with the healthy unit.
I might get back to this irritating thing if I remember of anything barely useful.
I've swapped the CPU for a spare and IC23,24,26. Same thing.

I give up.

Re: Juno-106 Restoration story/Power Supply woes
During Poly 1 mode, the voices immediately fall to lower duty cycle. You can hear them jump as soon as you press the key. During revolver 1-2 mode, it gets shifted after 6 key presses.Mooger5 wrote:Poly 1 selected in tezt mode so all voices sound at once, too?
Re: Juno-106 Restoration story/Power Supply woes
Wait... I'm not sure I understand how it's going on afterall. It begins to sound like it's a bad or wrongly set potentiometer during calibration...
Would you mind explaining step by step what happens?
Thanks.
Would you mind explaining step by step what happens?
Thanks.
Herrare umanum est.
Re: Juno-106 Restoration story/Power Supply woes
Step-by-step:Mooger5 wrote:Wait... I'm not sure I understand how it's going on afterall. It begins to sound like it's a bad or wrongly set potentiometer during calibration...
Would you mind explaining step by step what happens?
Thanks.
Unit turn-on, into test mode.
Load bank 5.
Switch on Poly 1 Unison. Voices IMMEDIATELY fall to 20% and less PWM on C4. Out of bounds for VR-adjustment.
Switch to Poly 1-2 Revolver. Press C6. Press and hold C4. Normal PWM of 50%, well within VR adjustment bounds.
Continue pressing C4. Next voices also hold PWM on 50% without any problems UNTIL we hit it for the 6th time. Then, PWM jumps back to around 20% on C4, which is distinctly heard.
I will shoot a video later.
Re: Juno-106 Restoration story/Power Supply woes
When voices immediately fall to 20%, try moving the PW fader down to Zero...
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Re: Juno-106 Restoration story/Power Supply woes
It's not something obvious as this.Mooger5 wrote:When voices immediately fall to 20%, try moving the PW fader down to Zero...


Re: Juno-106 Restoration story/Power Supply woes
Yeah I remember.
Unfixable. Smash it!
Unfixable. Smash it!
Herrare umanum est.
Re: Juno-106 Restoration story/Power Supply woes
Joking. Sort of. Wouldn´t be surprised if it was some stupid little thing so obvious that we´re overlooking. If you ever find a culprit please report. 

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Re: Juno-106 Restoration story/Power Supply woes
Just noticed in the video the 75% duty cycle has a negative bias when the output should be symmetrical. So another part that´s common to all voices is TR7 and associated resistors. It´s labeled Q7 in the PCB. I´m only guessing that it´s locally regulating a negative voltage to the demux. Maybe the transistor is leaky?
Herrare umanum est.