[sdiy] Juno 60 woes

Jack Jackson jackdamery at hotmail.co.uk
Wed Jun 10 22:59:34 CEST 2015


Hi,

Before anything, have you run through the calibration procedure?

Best,
Jack

----------------------------------------
> From: synthesizerdiy at gmail.com
> To: jackdamery at hotmail.co.uk
> Subject: Re: [sdiy] Juno 60 woes
> Date: Wed, 10 Jun 2015 12:19:14 -0500
>
> Since it seems you might have some intimate knowledge of the Junos at
> this point, would you happen to know where to look for an issue with
> the ADSR on a Juno 6? The release sliders does nothing and seems to
> output some release regardless where the slider is positioned. The AD
> seem to work and the S is questionable. I cannot find any position of
> any adjustment on the Synth to get any "R" to work or show any signs
> of life.
>
> The synth has been fully recapped and cleaned. I have taken a look at
> the Juno 6 service notes.pdf and see that the slider for the "R" is
> VR12 and the amp IC should be IC11. Swapping IC11 had no change. I
> did however get the IC11 from UTSource.
>
> Would you happen to know any area to look at to resolve this problem?
>
> Thank you for your time,
>
>
>
>
>
> On Jun 10, 2015, at 8:28 AM, Jack Jackson wrote:
>
>> Success!
>>
>> So I swapped out:
>>
>> 4049: IC 52 + IC53
>> 4099: IC 50
>> 4011: IC 48 + IC49
>> 4069: IC57
>> 74LS42: IC58
>>
>> It looks like a transient blew through all these logic chips. The
>> bottleneck that actually stopped the CPU functioning seemed to be
>> the 4049s.
>>
>> The synth now seems to be completely working except the bias of
>> voice 2 on the VCA out test point is way above everything else.
>>
>> Thank you all for your help!
>> Jack
>>
>> ----------------------------------------
>>> Date: Mon, 8 Jun 2015 14:44:54 -0400
>>> Subject: Re: [sdiy] Juno 60 woes
>>> From: bachmanm50 at gmail.com
>>> To: jackdamery at hotmail.co.uk
>>>
>>> Jack
>>>
>>> Well,, Pin 19 does not go to the IC53 or IC58 like 17 does.. could be
>>> a sign... The 4049 IC also has some rather odd symbol markings on
>>> those upper two inverters, makes me wonder if there are some tack-ons
>>> there?.. maybe pop those ICs one at a time and see if your single
>>> starts looking better (going to ground, no "mixing" of signals)
>>>
>>> Good luck
>>>
>>> Mike
>>>
>>> On Mon, Jun 8, 2015 at 4:45 AM, Jack Jackson <jackdamery at hotmail.co.uk
>>>> wrote:
>>>> Hi Tom,
>>>>
>>>> Certainly it's a consideration. The board looks clean. I ran some
>>>> impedance tests and didn't see anything awry. A colleague pointed
>>>> out if you look at the second waveform compared to the first that
>>>> it's never reaching ground, so something must be pulling it up.
>>>> Also there seems to be a second waveform mixed in, so possibly the
>>>> line is shorted to another at some point.
>>>>
>>>> Best,
>>>> Jack
>>>>
>>>>> Subject: Re: [sdiy] Juno 60 woes
>>>>> From: tom at electricdruid.net
>>>>> Date: Mon, 8 Jun 2015 00:04:59 +0100
>>>>> CC: synth-diy at dropmix.xs4all.nl
>>>>> To: jackdamery at hotmail.co.uk
>>>>>
>>>>> Is the Juno60 at all like the Poly6, where the tracks get
>>>>> corroded and all kinds of weird stuff happens? Dodgy address
>>>>> lines sounds like it.
>>>>>
>>>>> My Poly6 kept throwing all kinds of weird faults all over the
>>>>> place, but eventually, they were all traceable to corroded lines
>>>>> on one of the processor busses. Working out that everything that
>>>>> went faulty was on the same bus was the key thing that identified
>>>>> the problem. Once I'd patched some wires in across the damaged
>>>>> tracks, everything started to spring back to life.
>>>>>
>>>>> HTH,
>>>>> Tom
>>>>>
>>>>> On 7 Jun 2015, at 23:30, Jack Jackson <jackdamery at hotmail.co.uk>
>>>>> wrote:
>>>>>
>>>>>> Hi all,
>>>>>>
>>>>>> The CPU seems to be locking up/malfunctioning due to a dodgy
>>>>>> address line. I think I've tracked it down to pin 17 of the CPU
>>>>>> on the CPU board, highlighted in blue on the linked diagram. I
>>>>>> measure this line compared to the other three address lines with
>>>>>> my scope. The level is only 382mV (on a x10 probe) compare to
>>>>>> 500mv of the other three lines. As you can see it connects to
>>>>>> multiple places. Apart from just aimlessly replacing all the
>>>>>> chips any likely areas or surefire ways to locate the problem?
>>>>>> Cheers.
>>>>>>
>>>>>> The diagram : https://www.flickr.com/gp/131625832@N02/h25cB9
>>>>>> ----------------------------------------
>>>>>>> Date: Fri, 5 Jun 2015 15:10:03 -0700
>>>>>>> From: grant at musictechnologiesgroup.com
>>>>>>> To: synth-diy at dropmix.xs4all.nl
>>>>>>> Subject: Re: [sdiy] Juno 60 woes
>>>>>>>
>>>>>>> He lifted the INT pin but didn't use a pullup so those tests he
>>>>>>> did were
>>>>>>> useless if you ask me.
>>>>>>>
>>>>>>> On 6/5/2015 7:12 AM, Richie Burnett wrote:
>>>>>>>> The CPU interrupt input should most likely be predominantly
>>>>>>>> high but
>>>>>>>> occasionally pulsing low. Probably something like every 1ms to
>>>>>>>> every
>>>>>>>> 100ms.
>>>>>>>>
>>>>>>>> Were all the other clock frequencies correct?
>>>>>>>>
>>>>>>>> -Richie,
>>>>>>>>
>>>>>>>>
>>>>>>>> -----Original Message----- From: Jack Jackson
>>>>>>>> Sent: Friday, June 05, 2015 9:34 AM
>>>>>>>> To: Richie Burnett ; Sdiy
>>>>>>>> Subject: Re: [sdiy] Juno 60 woes
>>>>>>>>
>>>>>>>> Hi Richie,
>>>>>>>>
>>>>>>>> Thanks for your response.
>>>>>>>>
>>>>>>>> I think the interrupt is being generated (its active low and
>>>>>>>> the line is
>>>>>>>> at ground level).
>>>>>>>>
>>>>>>>> It seems that the INT is not being cleared by the CPU. Only
>>>>>>>> the top
>>>>>>>> octave (roughly) of keys seem to do anything. but they don't
>>>>>>>> seem to
>>>>>>>> relate to frequency correctly, they just play a frequency.
>>>>>>>>
>>>>>>>> Cheers,
>>>>>>>> Jack
>>>>>>>>
>>>>>>>> ----------------------------------------
>>>>>>>>> From: rburnett at richieburnett.co.uk
>>>>>>>>> To: jackdamery at hotmail.co.uk; synth-diy at dropmix.xs4all.nl
>>>>>>>>> Subject: Re: [sdiy] Juno 60 woes
>>>>>>>>> Date: Thu, 4 Jun 2015 22:15:48 +0100
>>>>>>>>>
>>>>>>>>> On Panel Board B, Check for...
>>>>>>>>>
>>>>>>>>> 4 MHz clock signal on pin 1 of IC26 (TC40H393P),
>>>>>>>>>
>>>>>>>>> 2 MHz clock signal on pin 3 of IC26 and also pin 20 of IC24,
>>>>>>>>>
>>>>>>>>> 500 kHz clock signal on pin 5 and pin 13 of IC26,
>>>>>>>>>
>>>>>>>>> 31.25 kHz clock signal on pin 8 of IC26,
>>>>>>>>>
>>>>>>>>> Periodic low pulses on pin 4 of IC27 (TC40H002P),
>>>>>>>>>
>>>>>>>>> Also check the voltage at pin 21 of IC24 relative to ground
>>>>>>>>> (pin4 same
>>>>>>>>> chip.)
>>>>>>>>>
>>>>>>>>> See bottom left corner of PANEL BOARD B schematic in Juno 60
>>>>>>>>> Service
>>>>>>>>> Notes.
>>>>>>>>> The circuit seems to mostly relate to the DCB interface, but
>>>>>>>>> appears
>>>>>>>>> to be
>>>>>>>>> where the main CPU board processor's interrupt signal is
>>>>>>>>> being generated,
>>>>>>>>> (or not being generated in your case.)
>>>>>>>>>
>>>>>>>>> Hope this helps. Good luck,
>>>>>>>>>
>>>>>>>>> -Richie,
>>>>>>>>>
>>>>>>>>> -----Original Message-----
>>>>>>>>> From: Jack Jackson
>>>>>>>>>
>>>>>>>>> OK so I tried bending up the int pin on the CPU and then
>>>>>>>>> inserting the
>>>>>>>>> chip
>>>>>>>>> so the INT pin is not connected. Now I appear to get a signal
>>>>>>>>> and some
>>>>>>>>> control of the parameters but only one frequency (one voice)
>>>>>>>>> and it
>>>>>>>>> stays on
>>>>>>>>> but I only hear this when i either press a key and then tap
>>>>>>>>> the INT
>>>>>>>>> pin with
>>>>>>>>> my finger, or move the bender and tap the INT pin.
>>>>>>>>>
>>>>>>>>> Any ideas?
>>>>>>>>>
>>>>>>>>
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