Did I Really Just Fry my Casio SK-1?!?!

[casio88]

Hi Benders,

Admittedly I'm a total noob...I picked up a Casio SK-1 today on Craigslist and was having some of the most creative fun I've had in years. It didn't come with a power adaptor and I mistakenly plugged in a 12v adaptor with reverse polarity. The power light on the keyboard still turns ON (even while the button is set to "off") but none of the buttons/keys produce any sound.

I can't believe I did this to something I was having so much fun with and just picked up. FML. Is it ruined?? Is there a fuse I can replace?? Any advice is greatly appreciated.

Thanks

[Circuitbenders]

Its going to be a dodgy transistor in the voltage regulation circuit. I'd guess T1, T2 or T3

You can find the service manual with a parts list at http://www.burnkit2600.com/manuals/CASIO_SK-1_SRVC.pdf

[ahabzutun]

Hi all!

I seem to have the same problem. It turns on but no sound at all. I proceeded to replace T1, T2 and T7 with 2SC1740STPR transistors (which should be an equivalent to the 2SC1740SQ transistors mentioned in the service manual). T8 was replaced with an 2SA934SR transistor (which, according to my research should be also equivalent to the 2SA934R transistor mentioned in the service manual). To no avail.

When I turn on the keyboard, T7 and T8 get really hot after a short while. I was actually able to hear some sound when I connected it to the loudspeaker. But it was really quiet and somehow distorted. The behaviour stayed the same even after replacing all the trannies. Any idea what I could check and/or replace? :/