[sdiy] Juno 60 dead CPU diagnosis

Guy Taylor geekon at gmail.com
Sun May 10 01:03:55 CEST 2015

Hi, not sure if this would work but i replaced my junos cpu with this
one: http://midipolis.blogspot.com.au/p/minerva-manual.html

I cant tell how cool it makes the juno. Full midi, extra envelopes etc... :)

If you can narrow down which chip is broken, you could contact the guy
makes it and ask what he thinks. Hes very helpful


> On 10 May 2015, at 3:00 am, "rsdio at audiobanshee.com" <rsdio at audiobanshee.com> wrote:
> My quick skimming of the Juno 60 Service Manual shows that there are two CPU chips. Which one are you referring to?
> Is there one of those CPU upgrade boards installed that might be replacing one of the CPUs?
> Grab the Service Manual online and go through the adjustments section. It has expected waveforms that you can check with a scope (or maybe even an audio interface, if you make some probes with audio wires).
> Brian
>> On May 9, 2015, at 8:33 AM, Jack Jackson <jackdamery at hotmail.co.uk> wrote:
>> I bought a non working Juno 60 today. During the buy I popped the lid and found one cable unplugged and another cable in its place. I put them back in the right place but no joy.
>> Things I checked that work:
>> 1. Power supply - Voltages are correctly adjusted according to service manual
>> 2. Chorus - When I turn the chorus on I can hear it hiss as expected.
>> 3. Output - Volume knob seems to work
>> 4. Raw waveform - All show sawtooth at test point 3.
>> 5. Patch LED display seems to allow you to choose different patches.
>> Things I checked that dont work:
>> 1. VCA output
>> 2. Gate output
>> 3. Keyboard - keyboard seems to have no effect on raw waveform frequency at test point 3.
>> 4. Test mode doesn't seem to do anything
>> I suspect it could be a dead CPU.  I tried removing the CPU chip and it seems to have no effect on the operation of anything that I listed above that worked - including the patch memory LED display.
>> Is there a way I could tell for super sure it is the CPU? If it is a dead CPU, what could have killed it? If it's dead where I can get a new one for cheap?
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