Search found 43 matches

by The LT
Sat Feb 09, 2019 7:50 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

When voices immediately fall to 20%, try moving the PW fader down to Zero... It's not something obvious as this. :) I know it sounds like it, but the PW fader is down at zero, and yes, I've pulled it down. When I do raise it, it only further lowers the duty cycle and doesn't return it to 50%. Fader...
by The LT
Sat Feb 09, 2019 5:14 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

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. Step-by-step: Unit turn-on, into test mode. Load bank 5. Switch on Poly 1 Unison. Voices I...
by The LT
Sat Feb 09, 2019 3:41 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

Mooger5 wrote:Poly 1 selected in tezt mode so all voices sound at once, too?
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.
by The LT
Sat Feb 09, 2019 2:08 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

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. Unfortunately, my oscilloscope is a puny Jyetech DSO shell. I've swapped the CPU for a s...
by The LT
Sat Feb 09, 2019 1:13 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

Don´t replace or socket any more chips. It won´t fix nor improve anything. Yeah, vr33 was a shot in the dark. I made the same old mistake of not verifying where C4 actually is in the keyboard. It´s shown in page 19 of the service manual. Please confirm it´s the exact same key that was used for PWM ...
by The LT
Sat Feb 09, 2019 1:54 am
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

Socketed IC 10, 2 and 6, tried brand new TI CD4052BE in them. Same problem. Returned the original 4052s in the sockets. :) IC39 was indeed added when switching to external mode. I used an original NOS part. I have a spare. I will try to replace it tomorrow. I think I understood the DCO CV idea. I've...
by The LT
Sat Feb 09, 2019 12:12 am
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

I don´t really think all three chips would fail at the same time. Could be something common to all three though. What about Key Transpose and octave shift? When transposing by say a fifth, does it affect anything? Does it matter if 16, 8 or 4 is selected? I´d look at the processor, ROM and latch ch...
by The LT
Fri Feb 08, 2019 11:13 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

Yeah, I know Poly-2 assigner logic, just wasn't sure about Poly-1. Actually, you confirmed it. :) I could not have put it into words better myself. :) Well, it's actually almost unnoticeable when playing the synth musically. The synth plays like it should and is almost indistinguishable from the fir...
by The LT
Fri Feb 08, 2019 6:53 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

C63/R119 measures 6.01V with PW slider all the way down and around 0.54 when it's up. Switching to saw gives the same peak-to-peak voltage on the TP outputs across the keyboard. The unit is otherwise fully calibrated. The 6V at R119 never changes and stays at 6V when the pulse width jump occurs. So ...
by The LT
Fri Feb 08, 2019 1:55 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

Thanks Mooger5, I'll get to the testing when I get to the workshop.
by The LT
Thu Feb 07, 2019 6:51 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

I've localized the bender problem to the bender potentiometer itself. I've swapped the bender assemblies between the units. The VR3/4/5 sliders check out fine. It seems the pot range is wrong. The original pot goes from 44k straight to 0 ohms on maximum deflection. The new syntaur pot goes to 47k to...
by The LT
Thu Feb 07, 2019 1:11 am
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

Hmmm. Not sure why the other unit doesn't have it? And swapping the waveshapers does not help. This isn't exactly audible per-se, but I hear differences between the patches that use PWM. The maximum PW also goes higher and almost to 0% duty cycle. After all I've been through, I just can't stop there...
by The LT
Thu Feb 07, 2019 12:24 am
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

If it´s every 6th note then it must be always the same voice, no? Not really. When POLY1-2 are enabled, I can rotate to, say, voice #3 and then hit the high note. The the PWM reset will occur on the next voice #3 activation, i.e. after 6 presses of C4. No matter the starting voice number, it always...
by The LT
Wed Feb 06, 2019 11:32 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

Just tried a 5534 swap from Unit #1. Same behaviour. This happens exactly after 6 presses of the C4 key. No particular 5534 to tie this to. Replaced IC17 just for the heck of it. No change. :)
by The LT
Wed Feb 06, 2019 10:51 pm
Forum: HELP!
Topic: Juno-106 Restoration story/Power Supply woes
Replies: 86
Views: 14228

Re: Juno-106 Restoration story/Power Supply woes

Now that you mention, with the DAC properly calibrated, the PWM CV should be steady and common to all notes. Any influence the pitch should have over the width of individual notes must be happening at the core of the waveshapers. It´s true the 5532 aren´t as easy to clone as the 80017. AR could hav...