[sdiy] Prophet-5 help?

Tom Wiltshire tom at electricdruid.net
Thu Sep 26 11:36:45 CEST 2019


If the pots are working, but the switches are not, what’s the difference between those two parts of the system?

The 4051’s that demux the CVs have their address lines driven by the same 14174 latches that control the switched functions (Program Latches 0,1,2), so why would so work and some not? The Gates are driven off the same set of latches too, so if the gates work, at least some of those latches are ok.

If the buttons affect the LEDs when you’re programming the synth, then the processor must be able to _read_ the switches and _write_ to the LEDs. If that’s not the case, the problem could be the 4514 decoder that reads the button states.

I’m assuming this is a hardware issue. It could still be firmware, if there was a significant revision of the pin-out somewhere, so that a newer firmware uses a different pins a select line, say.

It’s an interesting problem!

Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 25 Sep 2019, at 23:44, Eric Frampton <eric at ericframpton.com> wrote:
> 
> An update:
> 
> After receiving a new set of 8.2 EPROMs from a fellow listmember (thanks G!), the unit now appears to drop in and out of Record mode as it should.
> 
> Now however, if I create a preset by hand and try to save it to a patch location, it goes through the Record routine, but either isn’t getting saved correctly or isn’t getting recalled correctly.
> 
> If I attempt to load cassette data (I’ve tried files that I know have worked in other P-5’s), I can’t get the cassette load to complete (it always ends with a flashing LOAD LED) and, while there *is* data being loaded into memory, it always comes up scrambled. If I do repeated cassette loads and listen to the scrambled patches, they’re different after each load attempt.
> 
> When I recall these incorrect patches, all programmable latches/front panel buttons are set ON for every patch, it’s only the pot values that seem to be changing. The same behavior happens when I write/recall a patch that I’ve manually created - the pot values are correct, the latches are wrong (all switches are on).
> 
> e
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy





More information about the Synth-diy mailing list