Casio SA-9

[PolyPhuckin]

Alright people

First time posting on this board, but everyone sounds like they know what their doing, so i have a question...

...Im new to bending, but not electronics, im not a beginner when t comes to electronics, but i do stumble at a few things.

So i came to own a Casio SA-9 and decided to bend it, i found the timing crystal and decided it would be fun to slow it down, so i bought a 6Mhz timing crystal and hooked them both up to a DPDT switch so they coulf be changed easily, trouble is, whilst in this set up, the slower chip works fine, but the original 22Mhz (i think) crystal doesn't, but does work when wired back into the board.

Anyone have any advice on how to get both crystals working together?

Thanks in advance.

[Oceanus - XD515]

Hi Nick,
I know you mailed me about this, but I can answer it here.
The original crystal on the SA series has 3 legs ( unless you have the SA with the little daughter board ) The crystal contains 2 capacitors, that form an oscillator when the CPU feeds it a pulse. Switching in another (6Mhz) crystal requires the use of 2 extra 22pf caps, as per my schematic on casperelectronics. If you can't get the original crystal to work, I suspect there is a problem with the switch and you have got the extra capacitors in circuit with the original crystal. This increases the base loading capacitance to a point where the CPU cannot run. If you want to mail me a picture of your wiring, I'll see if I can spot anything out of the ordinary!.

Cheers,

Paul aka Oceanus.

[PolyPhuckin]

Well, i went back and had a look at my wiring (i have it set upon a bread board). It seems that the problem was the middle leg of the original crystal, bit of re-wiring and it worked.
At one point though, it was playing at an increased pitch for some reason.



After thought: the main chip can get quite hot. Will this be a problem in future?