[sdiy] Juno 60 dead CPU diagnosis

MTG grant at musictechnologiesgroup.com
Sat May 9 17:45:48 CEST 2015


vintageplanet.nl
vintagesynthshop.com

Just google juno 60 8049. There might even be 3rd party upgrade CPUs for it.

GB


On 5/9/2015 8:33 AM, Jack Jackson 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?
>
> Cheers,
> Jack 		 	   		
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