[sdiy] Juno 60 woes

Richie Burnett rburnett at richieburnett.co.uk
Fri Jun 5 16:12:34 CEST 2015

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?


-----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.


> 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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