CasioForest

Hi everyone and thanks a bunch for taking the time with your responses. They were very much helpful and i've already gone about cleaning the remaining alkaline residue off the case (thanks a bunch @pianokeyjoe)(after the fact when these photos were taken). Apologies for my late reply as it took me a bit to figure out how to get a photo posted here. You can see the residue and the 'burn' marks on the top side of the PCB. Fortunately, they seem very nominal and most of the spill occurred on the casing and doesn't seem to have affected any of the components or traces to the underside. One thing I did notice is that when trying to get voltages off of the 14049UB's, that it was difficult as it seemed some of the pins were rusting over a bit. the voltage was either real low or jumping about, i had to scratch away some of this residue to get a constant reading at around 5.5V. Figured I would mention that but it doesn't appear that the battery explosion affected the actual PCB, and from what I can remember, this unit was functioning after the rupture and removal of the damaged batteries. memory be hazy these days though. thanks a bunch @IanB for your reply, that does now make sense if my issue is with one of those 4049's. They do measure voltage though, but is it possible to still be damaged and measure a voltage? Sorry for the beginner questions. And thanks for the link to the service manual, if I keep on hitting a wall and grab it ill be sure to get a schematic up here if that is ok for the archives. Reckon it would be helpful for other folks in this situation. @Chasyour video is what eventually led me here lol! Your video(s) are great and were a wealth of knowledge and what made me dust off the m10 in the first place, realize it was dead, then somehow find this spot. Thanks a bunch, it was the only place I could find a clear gut shot before I eventually opened mine up. I'm going to go about remeasuring the voltages just for the sake of good practice, thanks again @IanB for showing me the error in my ways in where im putting my grounds. Gonna see where I can source those pins too for the LA4120 and see if things differ from the original voltages i pulled. If its not one of those chips and it may be a discreet component, how does one zero in on it? I was looking into using an audio probe but not sure where to start on the circuit just yet. Would that be a good approach to take to figure out whats wrong? Thanks again everyone for the help : )

hello everyone, long time listener but a first time caller. My beloved casio tone m10 has been giving me issue in that it isn’t producing any sounds anymore. It turns on with both a battery and power supply, and the volume control works and the floor noise is audible when the volume is turned all the way up (this hum is affected a bit when keys are depressed), but no actual sound as far as the 4 settings go. the vibrato switch doesn’t seem to affect the noise floor hum at all. So its safe to say its at least not the speaker as its amplifying fine and the problem persists through the outboard jack as well. I’m very very green with electronics and this is my first dive in diagnosing what specific component is giving me issue on the circuit. A visual noted some leaked battery evidence near the battery port but nothing that I could see on the traces or the circuit board. no obvious burned up components. There are what looks to be 'burn' marks on the top side of the circuit to the battery leak but nothing I could see in detriment to the underside traces. I couldn’t find a schematic or service manual, if anyone has either i'd be very much grateful. for the time being without, I started measuring the supply voltage for each of the following IC’s and transistors on the board with the following values. If i’m doing this wrong please stand me corrected. 2SK30 JFET=1.88V ????? 2SD400 NPN SILICON TRANSISTOR=5.30V TC40H004P HEX INVERTER=5.44V TC40H074P D-TYPE FLIPPY FLOPPY=5.48V 14049UB HEX INVERTER=5.30V 14049UB HEX INVERTER=5.30V D773G MAIN BRAIN=5.42V LA4120 AMP= (and I hope i'm measuring the right pins as I couldn't find a definitive data sheet . VCC+ on pin 1 and ground on 16, is this correct? if so, im not getting a reading. but if i go off the ground on pin 5 (if im assuming right), im getting 4.75V. what's weirder is that if i put my ground to the ground pin 8 on the 14049UB, the voltage for the la4120 reads out at 10.76V which seems high instinctively but then again im tripping my way through this and don't really know what I am doing ) S10L0025 (S10L0025C-2001 printing on component)=???? I couldn't find a data sheet for this little guy either I wasn’t able to get a measurement for the S10L0025 or the LA4120 as i couldn’t find a data sheet and didn’t want to risk probing about on an inline IC or one where I can’t make out the definitive polarity. If its safe to experiment with some deductive reasoning and the probe i’d love to get some kind of measurement to go off to help. I also wasn’t able to get a proper measurement for the 2SK30 Jfet as I’m not sure if i’m doing it correctly by measuring the voltage off the drain. Is this the correct approach to getting the voltage readings for that JFET? When I do try I get an increase in noise through the speaker when I probe the drain pin, and I do get a voltage reading of 1.88V. i’m not really sure where to go from here other than hoping this means that the chips are at least ok and the problem may be with one of the several electrolytic capacitors on the board. there are a number of diodes too that are not marked. could these be considered a viable suspect for what may be going wrong? could it be any of the resistors? How does one troubleshoot things further down to the very component if its not one of the chips? Thanks for any help folks, it would be amazing to get this up and running again to make some music with