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[gmeredith]

I have been doing some testing and some research about this, and have come to the conclusion that it is not possible to do this. I have a Casio DG20 digital guitar which I tried it on, without sucess. I can pretty much guarantee that all Casio keyboards with this feature, such as the SK5 and SK8, will behave in the same way.

I have sought to bypass the APO signal line from the DG20's processor and connect an external 5V supply to the power circuit transistors to keep the keyboard awake. I thought that this would do it, and now the rest of the keyboard does stay powered up, but the processor itself actually shuts itself down after 7 mins. The lights stay on, but nobody's home. The instrument will not operate.

Referring to the service manual, you can basically work out what i've done. But I believe the processor itself has a timer in it that is hard-wired internally in the chip that shuts the processor itself off, no matter what else goes on in the keyboard. That's a damn shame, I really thought I was on to something.

There IS one way that you can work around this feature, and that is to press any button or key on the keyboard every 6 or so minutes, before the APO switches off. Knowing this, it should be able to make a small timer circuit with a tiny relay or electronic switch that is hotwired to some relatively unused function button on the keyboard, that will do this automatically.

Anyone have anything to add to this?

Cheers, Graham

[nochtanseenspecht]

thanks for your research anyway. this casio feature irritates me since a long time

[gmeredith]

The annoying thing about it is that my CZ-101 has an APO on/off switch. Why did they only do it to this one, and not the others? And anyway, the SK keyboards hardly eat batteries, why bother even having an APO?

Cheers, Graham

[MagpieIndustries]

I saw an SK-1 mod somewhere that claimed to disable the auto power off, something to do with holding a processor line high. Cant rememebr where I saw it, or if it was genuine, cos I never tested it, but it was posted alongside a mod for disabling the drums by cutting a jumper, and that one worked at least...

[gmeredith]

Yes, I've read that sk1 mod, too. They found on the SK1 that it worked with the processor line held LOW, after their final investigations. I think they still had problems with it, though. The DG20 and SK5/8 are slightly different to the SK. The DG stays awake with the APO line high,  but the problem is is that the instrument analog circuits only stay awake, not the processor itself - and i suspect that some of the sk1 problems they are having are also along this line.
i'll have to get an SK1 sometime and study their claims more closely. Anyone here done the SK1 power off mod successfully?

Cheers, Graham

[gmeredith]

There IS one way that you can work around this feature, and that is to press any button or key on the keyboard every 6 or so minutes, before the APO switches off. Knowing this, it should be able to make a small timer circuit with a tiny relay or electronic switch that is hotwired to some relatively unused function button on the keyboard, that will do this automatically

I found a circuit to do exactly what I wanted here:

http://www3.telus.net/chemelec/Projects/Timer/Timer.htm


Here is an example circuit of the above:

http://www3.telus.net/chemelec/Projects/Timer/Timer-1.jpg


I'll let you know how it goes

Cheers, Graham

[nochtanseenspecht]

btw, i wrote a complain to casio about the "auto power shut off" 
i asked them if there is a trick to overrule the APO function,
and this was their (probably standard) answer :

Dear Mr. Leerink,

Thank you very much for your letter and your interest in our products.

Your comments will be forwarded to our product development centre in
Japan. As it is very important for us to offer high quality products that
meet the demands and expectations of our customers we can assure you,
that your suggestions will be thoroughly discussed and possibly even
considered for implementation in future generations of this product.


Best regards
Casio Europe GmbH

Katrin Hebestreit
European Support Center

well. at least nice of them to answer me, and perhaps hopefull for future generation 

[gmeredith]

Some lucky robot in the year 3356 will be playing a Casio with an APO selector switch, damn I'm jealous!!

Cheers, Graham

[bendboy]

I found the power off can be extended also by lowering the clock speed, makes sense-it counts 'X' clocks then goes to sleep! If the clock is totally stopped, I suppose it could be in 'suspended animation' for any time....
Maybe there is some unused I/O lines that do nothing(nothing programmed) but still reset the APO?
I have an SK-1 to play with on this.....

[gmeredith]

This is quite possible - on the MT65 you can genuinely disable the APO by this method

Cheers, Graham