Casio CZ/ VZ/ FZ - Pro Series

Hi Steph!

So there could be different errors:

The 74HC241 is damaged: change necessary

The KI6 line has a short to GND or VCC

If you have an oscilloscope or logic analyzer you could check if the scan pattern will 
be received on this line (Pin 13) if one of the keys in this line is pressed. 
If not than there may be a short to GND or VCC...

If you can measure the pattern than check if the HC241 gives this pattern on its output (Pin 7) 
if the Buffer Enable (Pin19) is enabled (High). If not the HC241 could be damaged - exchange it!

If you don't have a scope nor a logic analyzer but you are able to built quite simple circuits than
You could think of builing a simple and cheap 4 Bit logic analyzer that works via a serial interface
Or with an USB to serial converter via USB. The Scanalogic: www.ikalogic.com/scanalogic_home.php
If you built the 16MHz crystal version (data for it and HEX files can be found in the Forum on this page) 
it is able to scan with 4MHz - that's enough for the keyboard scanner to check. I built the scanalogic 
and it works fine!

Ciao
Peter

-----Original Message-----
From: CZsynth@yahoogroups.com [mailto:CZsynth@yahoogroups.com] On Behalf Of steph_g_87
Sent: Friday, April 16, 2010 10:14 AM
To: CZsynth@yahoogroups.com
Subject: [CZsynth] Re: CZ 101 lcd display

The K16 path is involved with other switches : preset 6, internal, DCW1 env, DCW2 env
and enventualy all the F and B keys ...

And guess what ? all of them don't work ! :))

I've checked the line from the key board/preset board/synth board
to the main board and right to the 74hc241 tri state buffer's pin 13 (2A2)
where the K16 ends and it's ok... so the problem is beyond this chip


--- In CZsynth@yahoogroups.com, "steph_g_87" <stephane.garrigue@...> wrote:
>
> Yeah thx ! I just have to follow the ja7 on the ma1m board
> that leads to the... pin 13 of the 74hc241 tri state buffer
> All I have to do is checking with my multi between the key contact and the chip pin
> thx !!
> 
> 
> --- In CZsynth@yahoogroups.com, Ullrich Peter <peter.ullrich@> wrote:

> > Due to the schematics it looks like the keyboard error has to be on the line KI6 as all 
> > F and B keys are controlled via this line. See schematics page 7.





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